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[[pp. 62243-62273]] Amendments for Testing and Monitoring Provisions
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
[Federal Register: October 17, 2000 (Volume 65, Number 201)]
[Rules and Regulations]
[Page 62243-62273]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17oc00-20]
[[pp. 62243-62273]] Amendments for Testing and Monitoring Provisions
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17.0 Tables, Diagrams, Flowcharts, and Validation Data
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BILLING CODE 6560-50-C
Method 306--Determination of Chromium Emissions From Decorative and
Hard Chromium Electroplating and Chromium Anodizing Operations--
Isokinetic Method
Note: This method does not include all of the specifications (e.g.,
equipment and supplies) and procedures (e.g., sampling and analytical)
essential to its performance. Some material is incorporated by
reference from other methods in 40 CFR Part 60, Appendix A. Therefore,
to obtain reliable results, persons using this method should have a
thorough knowledge of at least Method 5.
1.0 Scope and Application
1.1 Analytes.
------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Chromium...................... 7440-47-3........ See Sec. 13.2.
------------------------------------------------------------------------
1.2 Applicability. This method applies to the determination of
chromium (Cr) in emissions from decorative and hard chrome
electroplating facilities, chromium anodizing operations, and
continuous chromium plating operations at iron and steel facilities.
1.3 Data Quality Objectives. [Reserved]
2.0 Summary of Method
2.1 Sampling. An emission sample is extracted isokinetically from
the source using an unheated Method 5 sampling train (40 CFR Part 60,
Appendix A), with a glass nozzle and probe liner, but with the filter
omitted. The sample time shall be at least two hours. The Cr emissions
are collected in an alkaline solution containing 0.1 N sodium hydroxide
(NaOH) or 0.1 N sodium bicarbonate (NaHCO3). The collected
samples are recovered using an alkaline solution and are then
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transported to the laboratory for analysis.
2.2 Analysis.
2.2.1 Total chromium samples with high chromium concentrations
(35 g/L) may be analyzed using inductively coupled
plasma emission spectrometry (ICP) at 267.72 nm.
Note: The ICP analysis is applicable for this method only when
the solution analyzed has a Cr concentration greater than or equal
to 35 g/L or five times the method detection limit as
determined according to Appendix B in 40 CFR Part 136.
2.2.2 Alternatively, when lower total chromium concentrations (35
g/L) are encountered, a portion of the alkaline sample
solution may be digested with nitric acid and analyzed by graphite
furnace atomic absorption spectroscopy (GFAAS) at 357.9 nm.
2.2.3 If it is desirable to determine hexavalent chromium
(Cr+6) emissions, the samples may be analyzed using an ion
chromatograph equipped with a post-column reactor (IC/PCR) and a
visible wavelength detector. To increase sensitivity for trace levels
of Cr+6, a preconcentration system may be used in
conjunction with the IC/PCR.
3.0 Definitions
3.1 Total Chromium--measured chromium content that includes both
major chromium oxidation states (Cr+3, Cr+3).
3.2 May--Implies an optional operation.
3.3 Digestion--The analytical operation involving the complete (or
nearly complete) dissolution of the sample in order to ensure the
complete solubilization of the element (analyte) to be measured.
3.4 Interferences--Physical, chemical, or spectral phenomena that
may produce a high or low bias in the analytical result.
3.5 Analytical System--All components of the analytical process
including the sample digestion and measurement apparatus.
3.6 Sample Recovery--The quantitative transfer of sample from the
collection apparatus to the sample preparation (digestion, etc.)
apparatus. This term should not be confused with analytical recovery.
3.7 Matrix Modifier--A chemical modification to the sample during
GFAAS determinations to ensure that the analyte is not lost during the
measurement process (prior to the atomization stage)
3.8 Calibration Reference Standards--Quality control standards
used to check the accuracy of the instrument calibration curve prior to
sample analysis.
3.9 Continuing Check Standard--Quality control standards used to
verify that unacceptable drift in the measurement system has not
occurred.
3.10 Calibration Blank--A blank used to verify that there has been
no unacceptable shift in the baseline either immediately following
calibration or during the course of the analytical measurement.
3.11 Interference Check--An analytical/measurement operation that
ascertains whether a measurable interference in the sample exists.
3.12 Interelement Correction Factors--Factors used to correct for
interfering elements that produce a false signal (high bias).
3.13 Duplicate Sample Analysis--Either the repeat measurement of a
single solution or the measurement of duplicate preparations of the
same sample. It is important to be aware of which approach is required
for a particular type of measurement. For example, no digestion is
required for the ICP determination and the duplicate instrument
measurement is therefore adequate whereas duplicate digestion/
instrument measurements are required for GFAAS.
3.14 Matrix Spiking--Analytical spikes that have been added to the
actual sample matrix either before (Section 9.2.5.2) or after (Section
9.1.6). Spikes added to the sample prior to a preparation technique
(e.g., digestion) allow for the assessment of an overall method
accuracy while those added after only provide for the measurement
accuracy determination.
4.0 Interferences
4.1 ICP Interferences.
4.1.1 ICP Spectral Interferences. Spectral interferences are
caused by: overlap of a spectral line from another element; unresolved
overlap of molecular band spectra; background contribution from
continuous or recombination phenomena; and, stray light from the line
emission of high-concentrated elements. Spectral overlap may be
compensated for by correcting the raw data with a computer and
measuring the interfering element. At the 267.72 nm Cr analytical
wavelength, iron, manganese, and uranium are potential interfering
elements. Background and stray light interferences can usually be
compensated for by a background correction adjacent to the analytical
line. Unresolved overlap requires the selection of an alternative
chromium wavelength. Consult the instrument manufacturer's operation
manual for interference correction procedures.
4.1.2 ICP Physical Interferences. High levels of dissolved solids
in the samples may cause significant inaccuracies due to salt buildup
at the nebulizer and torch tips. This problem can be controlled by
diluting the sample or by extending the rinse times between sample
analyses. Standards shall be prepared in the same solution matrix as
the samples (i.e., 0.1 N NaOH or 0.1 N NaHCO3).
4.1.3 ICP Chemical Interferences. These include molecular compound
formation, ionization effects and solute vaporization effects, and are
usually not significant in the ICP procedure, especially if the
standards and samples are matrix matched.
4.2 GFAAS Interferences.
4.2.1 GFAAS Chemical Interferences. Low concentrations of calcium
and/or phosphate may cause interferences; at concentrations above 200
g/L, calcium's effect is constant and eliminates the effect of
phosphate. Calcium nitrate is therefore added to the concentrated
analyte to ensure a known constant effect. Other matrix modifiers
recommended by the instrument manufacturer may also be considered.
4.2.2 GFAAS Cyanide Band Interferences. Nitrogen should not be
used as the purge gas due to cyanide band interference.
4.2.3 GFAAS Spectral Interferences. Background correction may be
required because of possible significant levels of nonspecific
absorption and scattering at the 357.9 nm analytical wavelength.
4.2.4 GFAAS Background Interferences. Zeeman or Smith-Hieftje
background correction is recommended for interferences resulting from
high levels of dissolved solids in the alkaline impinger solutions.
4.3 IC/PCR Interferences.
4.3.1 IC/PCR Chemical Interferences. Components in the sample
matrix may cause Cr+6 to convert to trivalent chromium
(Cr+3) or cause Cr+3 to convert to
Cr+6. The chromatographic separation of Cr+6
using ion chromatography reduces the potential for other metals to
interfere with the post column reaction. For the IC/PCR analysis, only
compounds that coelute with Cr+6 and affect the
diphenylcarbazide reaction will cause interference.
4.3.2 IC/PCR Background Interferences. Periodic analyses of
reagent water blanks are used to demonstrate that the analytical system
is essentially free of contamination. Sample cross-contamination can
occur when high-level and low-level samples or standards are analyzed
alternately and can be eliminated by thorough purging of the sample
loop. Purging of
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the sample can easily be achieved by increasing the injection volume to
ten times the size of the sample loop.
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of
the user to establish appropriate safety and health practices and to
determine the applicability of regulatory limitations prior to
performing this test method.
5.2 Hexavalent chromium compounds have been listed as carcinogens
although chromium (III) compounds show little or no toxicity. Chromium
can be a skin and respiratory irritant.
6.0 Equipment and Supplies
6.1 Sampling Train.
6.1.1 A schematic of the sampling train used in this method is
shown in Figure 306-1. The train is the same as shown in Method 5,
Section 6.0 (40 CFR Part 60, Appendix A) except that the probe liner is
unheated, the particulate filter is omitted, and quartz or borosilicate
glass must be used for the probe nozzle and liner in place of stainless
steel.
6.1.2 Probe fittings of plastic such as Teflon, polypropylene,
etc. are recommended over metal fittings to prevent contamination. If
desired, a single combined probe nozzle and liner may be used, but such
a single glass assembly is not a requirement of this methodology.
6.1.3 Use 0.1 N NaOH or 0.1 N NaHCO3 in the impingers
in place of water.
6.1.4 Operating and maintenance procedures for the sampling train
are described in APTD-0576 of Method 5. Users should read the APTD-0576
document and adopt the outlined procedures.
6.1.5 Similar collection systems which have been approved by the
Administrator may be used.
6.2 Sample Recovery. Same as Method 5, [40 CFR Part 60, Appendix
A], with the following exceptions:
6.2.1 Probe-Liner and Probe-Nozzle Brushes. Brushes are not
necessary for sample recovery. If a probe brush is used, it must be
non-metallic.
6.2.2 Sample Recovery Solution. Use 0.1 N NaOH or 0.1 N
NaHCO3, whichever is used as the impinger absorbing
solution, in place of acetone to recover the sample.
6.2.3 Sample Storage Containers. Polyethylene, with leak-free
screw cap, 250 mL, 500 mL or 1,000 mL.
6.3 Analysis.
6.3.1 General. For analysis, the following equipment is needed.
6.3.1.1 Phillips Beakers. (Phillips beakers are preferred, but
regular beakers may also be used.)
6.3.1.2 Hot Plate.
6.3.1.3 Volumetric Flasks. Class A, various sizes as appropriate.
6.3.1.4 Assorted Pipettes.
6.3.2 Analysis by ICP.
6.3.2.1 ICP Spectrometer. Computer-controlled emission
spectrometer with background correction and radio frequency generator.
6.3.2.2 Argon Gas Supply. Welding grade or better.
6.3.3 Analysis by GFAAS.
6.3.3.1 Chromium Hollow Cathode Lamp or Electrodeless Discharge
Lamp.
6.3.3.2 Graphite Furnace Atomic Absorption Spectrophotometer.
6.3.3.3 Furnace Autosampler.
6.3.4 Analysis by IC/PCR.
6.3.4.1 IC/PCR System. High performance liquid chromatograph pump,
sample injection valve, post-column reagent delivery and mixing system,
and a visible detector, capable of operating at 520 nm-540 nm, all with
a non-metallic (or inert) flow path. An electronic peak area mode is
recommended, but other recording devices and integration techniques are
acceptable provided the repeatability criteria and the linearity
criteria for the calibration curve described in Section 10.4 can be
satisfied. A sample loading system is required if preconcentration is
employed.
6.3.4.2 Analytical Column. A high performance ion chromatograph
(HPIC) non-metallic column with anion separation characteristics and a
high loading capacity designed for separation of metal chelating
compounds to prevent metal interference. Resolution described in
Section 11.6 must be obtained. A non-metallic guard column with the
same ion-exchange material is recommended.
6.3.4.3 Preconcentration Column (for older instruments). An HPIC
non-metallic column with acceptable anion retention characteristics and
sample loading rates must be used as described in Section 11.6.
6.3.4.4 Filtration Apparatus for IC/PCR.
6.3.4.4.1 Teflon, or equivalent, filter holder to accommodate
0.45-m acetate, or equivalent, filter, if needed to remove
insoluble particulate matter.
6.3.4.4.2 0.45-m Filter Cartridge. For the removal of
insoluble material. To be used just prior to sample injection/analysis.
7.0 Reagents and Standards
Note: Unless otherwise indicated, all reagents should conform to
the specifications established by the Committee on Analytical
Reagents of the American Chemical Society (ACS reagent grade). Where
such specifications are not available, use the best available grade.
Reagents should be checked by the appropriate analysis prior to
field use to assure that contamination is below the analytical
detection limit for the ICP or GFAAS total chromium analysis; and
that contamination is below the analytical detection limit for
Cr+6 using IC/PCR for direct injection or, if selected,
preconcentration.
7.1 Sampling.
7.1.1 Water. Reagent water that conforms to ASTM Specification
D1193-77 or 91 Type II (incorporated by reference see Sec. 63.14). All
references to water in the method refer to reagent water unless
otherwise specified. It is recommended that water blanks be checked
prior to preparing the sampling reagents to ensure that the Cr content
is less than three (3) times the anticipated detection limit of the
analytical method.
7.1.2 Sodium Hydroxide (NaOH) Absorbing Solution, 0.1 N. Dissolve
4.0 g of sodium hydroxide in 1 liter of water to obtain a pH of
approximately 8.5.
7.1.3 Sodium Bicarbonate (NaHCO3) Absorbing Solution,
0.1 N. Dissolve approximately 8.5 g of sodium bicarbonate in 1 liter of
water to obtain a pH of approximately 8.3.
7.1.4 Chromium Contamination.
7.1.4.1 The absorbing solution shall not exceed the QC criteria
noted in Section 7.1.1 ( 3 times the instrument detection
limit).
7.1.4.2 When the Cr+6 content in the field samples
exceeds the blank concentration by at least a factor of ten (10),
Cr+6 blank concentrations 10 times the detection
limit will be allowed.
Note: At sources with high concentrations of acids and/or
SO2, the concentration of NaOH or NaHCO3
should be 0.5 N to insure that the pH of the solution
remains at or above 8.5 for NaOH and 8.0 for NaHCO3
during and after sampling.
7.1.5 Silica Gel. Same as in Method 5.
7.2 Sample Recovery.
7.2.1 0.1 N NaOH or 0.1 N NaHCO3. Use the same solution
for the sample recovery that is used for the impinger absorbing
solution.
7.2.2 pH Indicator Strip, for IC/PCR. pH indicator capable of
determining the pH of solutions between the pH range of 7 and 12, at
0.5 pH increments.
7.3 Sample Preparation and Analysis.
7.3.1 Nitric Acid (HNO3), Concentrated, for GFAAS.
Trace metals
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grade or better HNO3 must be used for reagent preparation.
The ACS reagent grade HNO3 is acceptable for cleaning
glassware.
7.3.2 HNO3, 1.0% (v/v), for GFAAS. Prepare, by slowly
stirring, 10 mL of concentrated HNO3) into 800 mL of reagent
water. Dilute to 1,000 mL with reagent water. The solution shall
contain less than 0.001 mg Cr/L.
7.3.3 Calcium Nitrate Ca(NO3)2 Solution (10
g Ca/mL) for GFAAS analysis. Prepare the solution by weighing
40.9 mg of Ca(NO3)2 into a 1 liter volumetric
flask. Dilute with reagent water to 1 liter.
7.3.4 Matrix Modifier, for GFAAS. See instrument manufacturer's
manual for suggested matrix modifier.
7.3.5 Chromatographic Eluent, for IC/PCR. The eluent used in the
analytical system is ammonium sulfate based.
7.3.5.1 Prepare by adding 6.5 mL of 29 percent ammonium hydroxide
(NH4OH) and 33 g of ammonium sulfate
((NH4)2SO4) to 500 mL of reagent
water. Dilute to 1 liter with reagent water and mix well.
7.3.5.2 Other combinations of eluents and/or columns may be
employed provided peak resolution, repeatability, linearity, and
analytical sensitivity as described in Sections 9.3 and 11.6 are
acceptable.
7.3.6 Post-Column Reagent, for IC/PCR. An effective post-column
reagent for use with the chromatographic eluent described in Section
7.3.5 is a diphenylcarbazide (DPC)-based system. Dissolve 0.5 g of 1,5-
diphenylcarbazide in 100 mL of ACS grade methanol. Add 500 mL of
reagent water containing 50 mL of 96 percent spectrophotometric grade
sulfuric acid. Dilute to 1 liter with reagent water.
7.3.7 Chromium Standard Stock Solution (1000 mg/L). Procure a
certified aqueous standard or dissolve 2.829 g of potassium dichromate
(K2Cr2O7), in reagent water and dilute
to 1 liter.
7.3.8 Calibration Standards for ICP or IC/PCR. Prepare calibration
standards for ICP or IC/PCR by diluting the Cr standard stock solution
(Section 7.3.7) with 0.1 N NaOH or 0.1 N NaHCO3, whichever
is used as the impinger absorbing solution, to achieve a matrix similar
to the actual field samples. Suggested levels are 0, 50, 100, and 200
g Cr/L for ICP, and 0, 1, 5, and 10 g
Cr+6/L for IC/PCR.
7.3.9 Calibration Standards for GFAAS. Chromium solutions for
GFAAS calibration shall contain 1.0 percent (v/v) HNO3. The
zero standard shall be 1.0 percent (v/v) HNO3. Calibration
standards should be prepared daily by diluting the Cr standard stock
solution (Section 7.3.7) with 1.0 percent HNO3. Use at least
four standards to make the calibration curve. Suggested levels are 0,
10, 50, and 100 g Cr/L.
7.4 Glassware Cleaning Reagents.
7.4.1 HNO3, Concentrated. ACS reagent grade or
equivalent.
7.4.2 Water. Reagent water that conforms to ASTM Specification
D1193-77 or 91 Type II.
7.4.3 HNO3, 10 percent (v/v). Add by stirring 500 mL of
concentrated HNO3 into a flask containing approximately
4,000 mL of reagent water. Dilute to 5,000 mL with reagent water. Mix
well. The reagent shall contain less than 2 g Cr/L.
7.5 Quality Assurance Audit Samples.
7.5.1 When making compliance determinations, and upon
availability, audit samples shall be obtained from the appropriate EPA
regional Office or from the responsible enforcement authority and
analyzed in conjunction with the field samples.
7.5.2 If EPA or National Institute of Standards and Technology
(NIST) reference audit sample are not available, a mid-range standard,
prepared from an independent commercial source, may be used.
Note: To order audit samples, contact the responsible
enforcement authority at least 30 days prior to the test date to
allow sufficient time for the audit sample to be delivered.
8.0 Sample Collection, Preservation, Holding Times, Storage, and
Transport
Note: Prior to sample collection, consideration should be given
to the type of analysis (Cr+\6\ or total Cr) that will be
performed. Which analysis option(s) will be performed will determine
which sample recovery and storage procedures will be required to
process the sample (See Figures 306-3 and 306-4).
8.1 Sample Collection. Same as Method 5 (40 CFR Part 60, Appendix
A), with the following exceptions.
8.1.1 Omit the particulate filter and filter holder from the
sampling train. Use a glass nozzle and probe liner instead of stainless
steel. Do not heat the probe. Place 100 mL of 0.1 N NaOH or 0.1 N
NaHCO3 in each of the first two impingers, and record the
data for each run on a data sheet such as shown in Figure 306-2.
8.1.2 Clean all glassware prior to sampling in hot soapy water
designed for laboratory cleaning of glassware. Next, rinse the
glassware three times with tap water, followed by three additional
rinses with reagent water. Then soak the glassware in 10% (v/v)
HNO3 solution for a minimum of 4 hours, rinse three times
with reagent water, and allow to air dry. Cover all glassware openings
where contamination can occur with Parafilm, or equivalent, until the
sampling train is assembled for sampling.
8.1.3 Train Operation. Follow the basic procedures outlined in
Method 5 in conjunction with the following instructions. Train sampling
rate shall not exceed 0.030 m\3\/min (1.0 cfm) during a run.
8.2 Sample Recovery. Follow the basic procedures of Method 5, with
the exceptions noted.
8.2.1 A particulate filter is not recovered from this train.
8.2.2 Tester shall select either the total Cr or Cr+\6\
sample recovery option.
8.2.3 Samples to be analyzed for both total Cr and
Cr+\6\, shall be recovered using the Cr+\6\
sample option (Section 8.2.6).
8.2.4 A field reagent blank shall be collected for either of the
Cr or the Cr+\6\ analysis. If both analyses (Cr and
Cr+\6\) are to be conducted on the samples, collect separate
reagent blanks for each analysis.
Note: Since particulate matter is not usually present at
chromium electroplating and/or chromium anodizing operations, it is
not necessary to filter the Cr+\6\ samples unless there
is observed sediment in the collected solutions. If it is necessary
to filter the Cr+\6\ solutions, please refer to Method
0061, Determination of Hexavalent Chromium Emissions From Stationary
Sources, Section 7.4, Sample Preparation in SW-846 (see Reference
1).
8.2.5 Total Cr Sample Option.
8.2.5.1 Container No. 1. Measure the volume of the liquid in the
first, second, and third impingers and quantitatively transfer into a
labeled sample container.
8.2.5.2 Use approximately 200 to 300 mL of the 0.1 N NaOH or 0.1 N
NaHCO3 absorbing solution to rinse the probe nozzle, probe
liner, three impingers, and connecting glassware; add this rinse to
Container No. 1.
8.2.6 Cr+\6\ Sample Option.
8.2.6.1 Container No. 1. Measure and record the pH of the
absorbing solution contained in the first impinger at the end of the
sampling run using a pH indicator strip. The pH of the solution must be
8.5 for NaOH and 8.0 for NaHCO3. If it
is not, discard the collected sample, increase the normality of the
NaOH or NaHCO3 impinger absorbing solution to 0.5 N or to a
solution normality approved by the Administrator and collect another
air emission sample.
8.2.6.2 After determining the pH of the first impinger solution,
combine and measure the volume of the liquid in the first, second, and
third impingers and
[[Page 62250]]
quantitatively transfer into the labeled sample container. Use
approximately 200 to 300 mL of the 0.1 N NaOH or 0.1 N
NaHCO3 absorbing solution to rinse the probe nozzle, probe
liner, three impingers, and connecting glassware; add this rinse to
Container No. 1.
8.2.7 Field Reagent Blank.
8.2.7.1 Container No. 2.
8.2.7.2 Place approximately 500 mL of the 0.1 N NaOH or 0.1 N
NaHCO3 absorbing solution into a labeled sample container.
8.3 Sample Preservation, Storage, and Transport.
8.3.1 Total Cr Sample Option. Samples to be analyzed for total Cr
need not be refrigerated.
8.3.2 Cr+\6\ Sample Option. Samples to be analyzed for
Cr+\6\ must be shipped and stored at 4 deg.C. Allow
Cr+\6\ samples to return to ambient temperature prior to
analysis.
8.4 Sample Holding Times.
8.4.1 Total Cr Sample Option. Samples to be analyzed for total Cr
shall be analyzed within 60 days of collection.
8.4.2 Cr+\6\ Sample Option. Samples to be analyzed for
Cr+\6\ shall be analyzed within 14 days of collection.
9.0 Quality Control
9.1 ICP Quality Control.
9.1.1 ICP Calibration Reference Standards. Prepare a calibration
reference standard using the same alkaline matrix as the calibration
standards; it should be at least 10 times the instrumental detection
limit.
9.1.1.1 This reference standard must be prepared from a different
Cr stock solution source than that used for preparation of the
calibration curve standards.
9.1.1.2 Prior to sample analysis, analyze at least one reference
standard.
9.1.1.3 The calibration reference standard must be measured within
10 percent of it's true value for the curve to be considered valid.
9.1.1.4 The curve must be validated before sample analyses are
performed.
9.1.2 ICP Continuing Check Standard.
9.1.2.1 Perform analysis of the check standard with the field
samples as described in Section 11.2 (at least after every 10 samples,
and at the end of the analytical run).
9.1.2.2 The check standard can either be the mid-range calibration
standard or the reference standard. The results of the check standard
shall agree within 10 percent of the expected value; if not, terminate
the analyses, correct the problem, recalibrate the instrument, and
rerun all samples analyzed subsequent to the last acceptable check
standard analysis.
9.1.3 ICP Calibration Blank.
9.1.3.1 Perform analysis of the calibration blank with the field
samples as described in Section 11.2 (at least after every 10 samples,
and at the end of the analytical run).
9.1.3.2 The results of the calibration blank shall agree within
three standard deviations of the mean blank value. If not, analyze the
calibration blank two more times and average the results. If the
average is not within three standard deviations of the background mean,
terminate the analyses, correct the problem, recalibrate, and reanalyze
all samples analyzed subsequent to the last acceptable calibration
blank analysis.
9.1.4 ICP Interference Check. Prepare an interference check
solution that contains known concentrations of interfering elements
that will provide an adequate test of the correction factors in the
event of potential spectral interferences.
9.1.4.1 Two potential interferences, iron and manganese, may be
prepared as 1000 g/mL and 200 g/mL solutions,
respectively. The solutions should be prepared in dilute
HNO3 (1-5 percent). Particular care must be used to ensure
that the solutions and/or salts used to prepare the solutions are of
ICP grade purity (i.e., that no measurable Cr contamination exists in
the salts/solutions). Commercially prepared interfering element check
standards are available.
9.1.4.2 Verify the interelement correction factors every three
months by analyzing the interference check solution. The correction
factors are calculated according to the instrument manufacturer's
directions. If the interelement correction factors are used properly,
no false Cr should be detected.
9.1.4.3 Negative results with an absolute value greater than three
(3) times the detection limit are usually the results of the background
correction position being set incorrectly. Scan the spectral region to
ensure that the correction position has not been placed on an
interfering peak.
9.1.5 ICP Duplicate Sample Analysis. Perform one duplicate sample
analysis for each compliance sample batch (3 runs).
9.1.5.1 As there is no sample preparation required for the ICP
analysis, a duplicate analysis is defined as a repeat analysis of one
of the field samples. The selected sample shall be analyzed using the
same procedures that were used to analyze the original sample.
9.1.5.2 Duplicate sample analyses shall agree within 10 percent of
the original measurement value.
9.1.5.3 Report the original analysis value for the sample and
report the duplicate analysis value as the QC check value. If agreement
is not achieved, perform the duplicate analysis again. If agreement is
not achieved the second time, perform corrective action to identify and
correct the problem before analyzing the sample for a third time.
9.1.6 ICP Matrix Spiking. Spiked samples shall be prepared and
analyzed daily to ensure that there are no matrix effects, that samples
and standards have been matrix-matched, and that the laboratory
equipment is operating properly.
9.1.6.1 Spiked sample recovery analyses should indicate a recovery
for the Cr spike of between 75 and 125 percent.
9.1.6.2 Cr levels in the spiked sample should provide final
solution concentrations that are within the linear portion of the
calibration curve, as well as, at a concentration level at least: equal
to that of the original sample; and, ten (10) times the detection
limit.
9.1.6.3 If the spiked sample concentration meets the stated
criteria but exceeds the linear calibration range, the spiked sample
must be diluted with the field absorbing solution.
9.1.6.4 If the recoveries for the Cr spiked samples do not meet
the specified criteria, perform corrective action to identify and
correct the problem prior to reanalyzing the samples.
9.1.7 ICP Field Reagent Blank.
9.1.7.1 Analyze a minimum of one matrix-matched field reagent
blank (Section 8.2.4) per sample batch to determine if contamination or
memory effects are occurring.
9.1.7.2 If contamination or memory effects are observed, perform
corrective action to identify and correct the problem before
reanalyzing the samples.
9.1.8 Audit Sample Analysis.
9.1.8.1 When the method is used to analyze samples to demonstrate
compliance with a source emission regulation, an audit sample must be
analyzed, subject to availability.
9.1.8.2 Concurrently analyze the audit sample and the compliance
samples in the same manner to evaluate the technique of the analyst and
the standards preparation.
9.1.8.3 The same analyst, analytical reagents, and analytical
system shall be used for the compliance samples and the audit sample.
If this condition is met, duplicate auditing of subsequent compliance
analyses for the same enforcement agency within a 30-day period is
waived. An audit sample set may not be used to validate different
[[Page 62251]]
sets of compliance samples under the jurisdiction of separate
enforcement agencies, unless prior arrangements have been made with
both enforcement agencies.
9.1.9 Audit Sample Results.
9.1.9.1 Calculate the audit sample concentrations and submit
results using the instructions provided with the audit samples.
9.1.9.2 Report the results of the audit samples and the compliance
determination samples along with their identification numbers, and the
analyst's name to the responsible enforcement authority. Include this
information with reports of any subsequent compliance analyses for the
same enforcement authority during the 30-day period.
9.1.9.3 The concentrations of the audit samples obtained by the
analyst shall agree within the values specified by the compliance
auditor. If the specified range is not met, reanalyze the compliance
and audit samples, and include initial and reanalysis values in the
test report.
9.1.9.4 Failure to meet the specified range may require retests
unless the audit problems are resolved. However, if the audit results
do not affect the compliance or noncompliance status of the affected
facility, the Administrator may waive the reanalysis requirement,
further audits, or retests and accept the results of the compliance
test. While steps are being taken to resolve audit analysis problems,
the Administrator may also choose to use the data to determine the
compliance or noncompliance status of the affected facility.
9.2 GFAAS Quality Control.
9.2.1 GFAAS Calibration Reference Standards. The calibration curve
must be verified by using at least one calibration reference standard
(made from a reference material or other independent standard material)
at or near the mid-range of the calibration curve.
9.2.1.1 The calibration curve must be validated before sample
analyses are performed.
9.2.1.2 The calibration reference standard must be measured within
10 percent of its true value for the curve to be considered valid.
9.2.2 GFAAS Continuing Check Standard.
9.2.2.1 Perform analysis of the check standard with the field
samples as described in Section 11.4 (at least after every 10 samples,
and at the end of the analytical run).
9.2.2.2 These standards are analyzed, in part, to monitor the life
and performance of the graphite tube. Lack of reproducibility or a
significant change in the signal for the check standard may indicate
that the graphite tube should be replaced.
9.2.2.3 The check standard may be either the mid-range calibration
standard or the reference standard.
9.2.2.4 The results of the check standard shall agree within 10
percent of the expected value.
9.2.2.5 If not, terminate the analyses, correct the problem,
recalibrate the instrument, and reanalyze all samples analyzed
subsequent to the last acceptable check standard analysis.
9.2.3 GFAAS Calibration Blank.
9.2.3.1 Perform analysis of the calibration blank with the field
samples as described in Section 11.4 (at least after every 10 samples,
and at the end of the analytical run).
9.2.3.2 The calibration blank is analyzed to monitor the life and
performance of the graphite tube as well as the existence of any memory
effects. Lack of reproducibility or a significant change in the signal,
may indicate that the graphite tube should be replaced.
9.2.3.3 The results of the calibration blank shall agree within
three standard deviations of the mean blank value.
9.2.3.4 If not, analyze the calibration blank two more times and
average the results. If the average is not within three standard
deviations of the background mean, terminate the analyses, correct the
problem, recalibrate, and reanalyze all samples analyzed subsequent to
the last acceptable calibration blank analysis.
9.2.4 GFAAS Duplicate Sample Analysis. Perform one duplicate
sample analysis for each compliance sample batch (3 runs).
9.2.4.1 A digested aliquot of the selected sample is processed and
analyzed using the identical procedures that were used for the whole
sample preparation and analytical efforts.
9.2.4.2 Duplicate sample analyses results incorporating duplicate
digestions shall agree within 20 percent for sample results exceeding
ten (10) times the detection limit.
9.2.4.3 Report the original analysis value for the sample and
report the duplicate analysis value as the QC check value.
9.2.4.4 If agreement is not achieved, perform the duplicate
analysis again. If agreement is not achieved the second time, perform
corrective action to identify and correct the problem before analyzing
the sample for a third time.
9.2.5 GFAAS Matrix Spiking.
9.2.5.1 Spiked samples shall be prepared and analyzed daily to
ensure that (1) correct procedures are being followed, (2) there are no
matrix effects and (3) all equipment is operating properly.
9.2.5.2 Cr spikes are added prior to any sample preparation.
9.2.5.3 Cr levels in the spiked sample should provide final
solution concentrations that are within the linear portion of the
calibration curve, as well as, at a concentration level at least: equal
to that of the original sample; and, ten (10) times the detection
limit.
9.2.5.4 Spiked sample recovery analyses should indicate a recovery
for the Cr spike of between 75 and 125 percent.
9.2.5.5 If the recoveries for the Cr spiked samples do not meet
the specified criteria, perform corrective action to identify and
correct the problem prior to reanalyzing the samples.
9.2.6 GFAAS Method of Standard Additions.
9.2.6.1 Method of Standard Additions. Perform procedures in
Section 5.4 of Method 12 (40 CFR Part 60, Appendix A)
9.2.6.2 Whenever sample matrix problems are suspected and
standard/sample matrix matching is not possible or whenever a new
sample matrix is being analyzed, perform referenced procedures to
determine if the method of standard additions is necessary.
9.2.7 GFAAS Field Reagent Blank.
9.2.7.1 Analyze a minimum of one matrix-matched field reagent
blank (Section 8.2.4) per sample batch to determine if contamination or
memory effects are occurring.
9.2.7.2 If contamination or memory effects are observed, perform
corrective action to identify and correct the problem before
reanalyzing the samples.
9.2.8 Audit Sample Analysis.
9.2.8.1 When the method is used to analyze samples to demonstrate
compliance with a source emission regulation, an audit sample must be
analyzed, subject to availability.
9.2.8.2 Concurrently analyze the audit sample and the compliance
samples in the same manner to evaluate the technique of the analyst and
the standards preparation.
9.2.8.3 The same analyst, analytical reagents, and analytical
system shall be used for the compliance samples and the audit sample.
If this condition is met, duplicate auditing of subsequent compliance
analyses for the same enforcement agency within a 30-day period is
waived. An audit sample set may not be used to validate different sets
of compliance samples under the jurisdiction of separate enforcement
agencies, unless prior arrangements have been made with both
enforcement agencies.
[[Page 62252]]
9.2.9 Audit Sample Results.
9.2.9.1 Calculate the audit sample concentrations and submit
results using the instructions provided with the audit samples.
9.2.9.2 Report the results of the audit samples and the compliance
determination samples along with their identification numbers, and the
analyst's name to the responsible enforcement authority. Include this
information with reports of any subsequent compliance analyses for the
same enforcement authority during the 30-day period.
9.2.9.3 The concentrations of the audit samples obtained by the
analyst shall agree within the values specified by the compliance
auditor. If the specified range is not met, reanalyze the compliance
and audit samples, and include initial and reanalysis values in the
test report.
9.2.9.4 Failure to meet the specified range may require retests
unless the audit problems are resolved. However, if the audit results
do not affect the compliance or noncompliance status of the affected
facility, the Administrator may waive the reanalysis requirement,
further audits, or retests and accept the results of the compliance
test. While steps are being taken to resolve audit analysis problems,
the Administrator may also choose to use the data to determine the
compliance or noncompliance status of the affected facility.
9.3 IC/PCR Quality Control.
9.3.1 IC/PCR Calibration Reference Standards.
9.3.1.1 Prepare a calibration reference standard at a
concentration that is at or near the mid-point of the calibration curve
using the same alkaline matrix as the calibration standards. This
reference standard should be prepared from a different Cr stock
solution than that used to prepare the calibration curve standards. The
reference standard is used to verify the accuracy of the calibration
curve.
9.3.1.2 The curve must be validated before sample analyses are
performed. Prior to sample analysis, analyze at least one reference
standard with an expected value within the calibration range.
9.3.1.3 The results of this reference standard analysis must be
within 10 percent of the true value of the reference standard for the
calibration curve to be considered valid.
9.3.2 IC/PCR Continuing Check Standard and Calibration Blank.
9.3.2.1 Perform analysis of the check standard and the calibration
blank with the field samples as described in Section 11.6 (at least
after every 10 samples, and at the end of the analytical run).
9.3.2.2 The result from the check standard must be within 10
percent of the expected value.
9.3.2.3 If the 10 percent criteria is exceeded, excessive drift
and/or instrument degradation may have occurred, and must be corrected
before further analyses can be performed.
9.3.2.4 The results of the calibration blank analyses must agree
within three standard deviations of the mean blank value.
9.3.2.5 If not, analyze the calibration blank two more times and
average the results.
9.3.2.6 If the average is not within three standard deviations of
the background mean, terminate the analyses, correct the problem,
recalibrate, and reanalyze all samples analyzed subsequent to the last
acceptable calibration blank analysis.
9.3.3 IC/PCR Duplicate Sample Analysis.
9.3.3.1 Perform one duplicate sample analysis for each compliance
sample batch (3 runs).
9.3.3.2 An aliquot of the selected sample is prepared and analyzed
using procedures identical to those used for the emission samples (for
example, filtration and/or, if necessary, preconcentration).
9.3.3.3 Duplicate sample injection results shall agree within 10
percent for sample results exceeding ten (10) times the detection
limit.
9.3.3.4 Report the original analysis value for the sample and
report the duplicate analysis value as the QC check value.
9.3.3.5 If agreement is not achieved, perform the duplicate
analysis again.
9.3.3.6 If agreement is not achieved the second time, perform
corrective action to identify and correct the problem prior to
analyzing the sample for a third time.
9.3.4 ICP/PCR Matrix Spiking. Spiked samples shall be prepared and
analyzed with each sample set to ensure that there are no matrix
effects, that samples and standards have been matrix-matched, and that
the equipment is operating properly.
9.3.4.1 Spiked sample recovery analysis should indicate a recovery
of the Cr+\6\ spike between 75 and 125 percent.
9.3.4.2 The spiked sample concentration should be within the
linear portion of the calibration curve and should be equal to or
greater than the concentration of the original sample. In addition, the
spiked sample concentration should be at least ten (10) times the
detection limit.
9.3.4.3 If the recoveries for the Cr+\6\ spiked samples
do not meet the specified criteria, perform corrective action to
identify and correct the problem prior to reanalyzing the samples.
9.3.5 IC/PCR Field Reagent Blank.
9.3.5.1 Analyze a minimum of one matrix-matched field reagent
blank (Section 8.2.4) per sample batch to determine if contamination or
memory effects are occurring.
9.3.5.2 If contamination or memory effects are observed, perform
corrective action to identify and correct the problem before
reanalyzing the samples.
9.3.6 Audit Sample Analysis.
9.3.6.1 When the method is used to analyze samples to demonstrate
compliance with source emission regulation, an audit sample must be
analyzed, subject to availability.
9.3.6.2 Concurrently analyze the audit sample and the compliance
samples in the same manner to evaluate the technique of the analyst and
the standards preparation.
9.3.6.3 The same analyst, analytical reagents, and analytical
system shall be used for the compliance samples and the audit sample.
If this condition is met, duplicate auditing of subsequent compliance
analyses for the same enforcement agency within a 30-day period is
waived. An audit sample set may not be used to validate different sets
of compliance samples under the jurisdiction of separate enforcement
agencies, unless prior arrangements have been made with both
enforcement agencies.
9.3.7 Audit Sample Results.
9.3.7.1 Calculate the audit sample concentrations and submit
results using the instructions provided with the audit samples.
9.3.7.2 Report the results of the audit samples and the compliance
determination samples along with their identification numbers, and the
analyst's name to the responsible enforcement authority. Include this
information with reports of any subsequent compliance analyses for the
same enforcement authority during the 30-day period.
9.3.7.3 The concentrations of the audit samples obtained by the
analyst shall agree within the values specified by the compliance
auditor. If the specified range is not met, reanalyze the compliance
and audit samples, and include initial and reanalysis values in the
test report.
9.3.7.4 Failure to meet the specified range may require retests
unless the audit problems are resolved. However, if the audit results
do not affect the compliance or noncompliance status of
[[Page 62253]]
the affected facility, the Administrator may waive the reanalysis
requirement, further audits, or retests and accept the results of the
compliance test. While steps are being taken to resolve audit analysis
problems, the Administrator may also choose to use the data to
determine the compliance or noncompliance status of the affected
facility.
10.0 Calibration and Standardization
10.1 Sampling Train Calibration. Perform calibrations described in
Method 5, (40 CFR Part 60, Appendix A). The alternate calibration
procedures described in Method 5, may also be used.
10.2 ICP Calibration.
10.2.1 Calibrate the instrument according to the instrument
manufacturer's recommended procedures, using a calibration blank and
three standards for the initial calibration.
10.2.2 Calibration standards should be prepared fresh daily, as
described in Section 7.3.8. Be sure that samples and calibration
standards are matrix matched. Flush the system with the calibration
blank between each standard.
10.2.3 Use the average intensity of multiple exposures (3 or more)
for both standardization and sample analysis to reduce random error.
10.2.4 Employing linear regression, calculate the correlation
coefficient .
10.2.5 The correlation coefficient must equal or exceed 0.995.
10.2.6 If linearity is not acceptable, prepare and rerun another
set of calibration standards or reduce the range of the calibration
standards, as necessary.
10.3 GFAAS Calibration.
10.3.1 For instruments that measure directly in concentration, set
the instrument software to display the correct concentration, if
applicable.
10.3.2 Curve must be linear in order to correctly perform the
method of standard additions which is customarily performed
automatically with most instrument computer-based data systems.
10.3.3 The calibration curve (direct calibration or standard
additions) must be prepared daily with a minimum of a calibration blank
and three standards that are prepared fresh daily.
10.3.4 The calibration curve acceptance criteria must equal or
exceed 0.995.
10.3.5 If linearity is not acceptable, prepare and rerun another
set of calibration standards or reduce the range of calibration
standards, as necessary.
10.4 IC/PCR Calibration.
10.4.1 Prepare a calibration curve using the calibration blank and
three calibration standards prepared fresh daily as described in
Section 7.3.8.
10.4.2 The calibration curve acceptance criteria must equal or
exceed 0.995.
10.4.3 If linearity is not acceptable, remake and/or rerun the
calibration standards. If the calibration curve is still unacceptable,
reduce the range of the curve.
10.4.4 Analyze the standards with the field samples as described
in Section 11.6.
11.0 Analytical Procedures
Note: The method determines the chromium concentration in
g Cr/mL. It is important that the analyst measure the field
sample volume prior to analyzing the sample. This will allow for
conversion of g Cr/mL to g Cr/sample.
11.1 ICP Sample Preparation.
11.1.1 The ICP analysis is performed directly on the alkaline
impinger solution; acid digestion is not necessary, provided the
samples and standards are matrix matched.
11.1.2 The ICP analysis should only be employed when the solution
analyzed has a Cr concentration greater than 35 g/L or five
times the method detection limit as determined according to Appendix B
in 40 CFR Part 136 or by other commonly accepted analytical procedures.
11.2 ICP Sample Analysis.
11.2.1 The ICP analysis is applicable for the determination of
total chromium only.
11.2.2 ICP Blanks. Two types of blanks are required for the ICP
analysis.
11.2.2.1 Calibration Blank. The calibration blank is used in
establishing the calibration curve. For the calibration blank, use
either 0.1 N NaOH or 0.1 N NaHCO3, whichever is used for the
impinger absorbing solution. The calibration blank can be prepared
fresh in the laboratory; it does not have to be prepared from the same
batch of solution that was used in the field. A sufficient quantity
should be prepared to flush the system between standards and samples.
11.2.2.2 Field Reagent Blank. The field reagent blank is collected
in the field during the testing program. The field reagent blank
(Section 8.2.4) is an aliquot of the absorbing solution prepared in
Section 7.1.2. The reagent blank is used to assess possible
contamination resulting from sample processing.
11.2.3 ICP Instrument Adjustment.
11.2.3.1 Adjust the ICP instrument for proper operating parameters
including wavelength, background correction settings (if necessary),
and interfering element correction settings (if necessary).
11.2.3.2 The instrument must be allowed to become thermally stable
before beginning measurements (usually requiring at least 30 min of
operation prior to calibration). During this warmup period, the optical
calibration and torch position optimization may be performed (consult
the operator's manual).
11.2.4 ICP Instrument Calibration.
11.2.4.1 Calibrate the instrument according to the instrument
manufacturer's recommended procedures, and the procedures specified in
Section 10.2.
11.2.4.2 Prior to analyzing the field samples, reanalyze the
highest calibration standard as if it were a sample.
11.2.4.3 Concentration values obtained should not deviate from the
actual values or from the established control limits by more than 5
percent, whichever is lower (see Sections 9.1 and 10.2).
11.2.4.4 If they do, follow the recommendations of the instrument
manufacturer to correct the problem.
11.2.5 ICP Operational Quality Control Procedures.
11.2.5.1 Flush the system with the calibration blank solution for
at least 1 min before the analysis of each sample or standard.
11.2.5.2 Analyze the continuing check standard and the calibration
blank after each batch of 10 samples.
11.2.5.3 Use the average intensity of multiple exposures for both
standardization and sample analysis to reduce random error.
11.2.6 ICP Sample Dilution.
11.2.6.1 Dilute and reanalyze samples that are more concentrated
than the linear calibration limit or use an alternate, less sensitive
Cr wavelength for which quality control data have already been
established.
11.2.6.2 When dilutions are performed, the appropriate factors
must be applied to sample measurement results.
11.2.7 Reporting Analytical Results. All analytical results should
be reported in g Cr/mL using three significant figures. Field
sample volumes (mL) must be reported also.
11.3 GFAAS Sample Preparation.
11.3.1 GFAAS Acid Digestion. An acid digestion of the alkaline
impinger solution is required for the GFAAS analysis.
11.3.1.1 In a beaker, add 10 mL of concentrated HNO3 to
a 100 mL sample aliquot that has been well mixed. Cover
[[Page 62254]]
the beaker with a watch glass. Place the beaker on a hot plate and
reflux the sample to near dryness. Add another 5 mL of concentrated
HNO3 to complete the digestion. Again, carefully reflux the
sample volume to near dryness. Rinse the beaker walls and watch glass
with reagent water.
11.3.1.2 The final concentration of HNO3 in the
solution should be 1 percent (v/v).
11.3.1.3 Transfer the digested sample to a 50-mL volumetric flask.
Add 0.5 mL of concentrated HNO3 and 1 mL of the 10
g/mL of Ca(NO3)2. Dilute to 50 mL with
reagent water.
11.3.2 HNO3 Concentration. A different final volume may
be used based on the expected Cr concentration, but the HNO3
concentration must be maintained at 1 percent (v/v).
11.4 GFAAS Sample Analysis.
11.4.1 The GFAAS analysis is applicable for the determination of
total chromium only.
11.4.2 GFAAS Blanks. Two types of blanks are required for the
GFAAS analysis.
11.4.2.1 Calibration Blank. The 1.0 percent HNO3 is the
calibration blank which is used in establishing the calibration curve.
11.4.2.2 Field Reagent Blank. An aliquot of the 0.1 N NaOH
solution or the 0.1 N NaHCO3 prepared in Section 7.1.2 is
collected for the field reagent blank. The field reagent blank is used
to assess possible contamination resulting from processing the sample.
11.4.2.2.1 The reagent blank must be subjected to the entire
series of sample preparation and analytical procedures, including the
acid digestion.
11.4.2.2.2 The reagent blank's final solution must contain the
same acid concentration as the sample solutions.
11.4.3 GFAAS Instrument Adjustment.
11.4.3.1 The 357.9 nm wavelength line shall be used.
11.4.3.2 Follow the manufacturer's instructions for all other
spectrophotometer operating parameters.
11.4.4 Furnace Operational Parameters. Parameters suggested by the
manufacturer should be employed as guidelines.
11.4.4.1 Temperature-sensing mechanisms and temperature
controllers can vary between instruments and/or with time; the validity
of the furnace operating parameters must be periodically confirmed by
systematically altering the furnace parameters while analyzing a
standard. In this manner, losses of analyte due to higher-than-
necessary temperature settings or losses in sensitivity due to less
than optimum settings can be minimized.
11.4.4.2 Similar verification of furnace operating parameters may
be required for complex sample matrices (consult instrument manual for
additional information). Calibrate the GFAAS system following the
procedures specified in Section 10.3.
11.4.5 GFAAS Operational Quality Control Procedures.
11.4.5.1 Introduce a measured aliquot of digested sample into the
furnace and atomize.
11.4.5.2 If the measured concentration exceeds the calibration
range, the sample should be diluted with the calibration blank solution
(1.0 percent HNO3) and reanalyzed.
11.4.5.3 Consult the operator's manual for suggested injection
volumes. The use of multiple injections can improve accuracy and assist
in detecting furnace pipetting errors.
11.4.5.4 Analyze a minimum of one matrix-matched reagent blank per
sample batch to determine if contamination or any memory effects are
occurring.
11.4.5.5 Analyze a calibration blank and a continuing check
standard after approximately every batch of 10 sample injections.
11.4.6 GFAAS Sample Dilution.
11.4.6.1 Dilute and reanalyze samples that are more concentrated
than the instrument calibration range.
11.4.6.2 If dilutions are performed, the appropriate factors must
be applied to sample measurement results.
11.4.7 Reporting Analytical Results.
11.4.7.1 Calculate the Cr concentrations by the method of standard
additions (see operator's manual) or, from direct calibration. All
dilution and/or concentration factors must be used when calculating the
results.
11.4.7.2 Analytical results should be reported in g Cr/mL
using three significant figures. Field sample volumes (mL) must be
reported also.
11.5 IC/PCR Sample Preparation.
11.5.1 Sample pH. Measure and record the sample pH prior to
analysis.
11.5.2 Sample Filtration. Prior to preconcentration and/or
analysis, filter all field samples through a 0.45-m filter.
The filtration step should be conducted just prior to sample injection/
analysis.
11.5.2.1 Use a portion of the sample to rinse the syringe
filtration unit and acetate filter and then collect the required volume
of filtrate.
11.5.2.2 Retain the filter if total Cr is to be determined also.
11.5.3 Sample Preconcentration (older instruments).
11.5.3.1 For older instruments, a preconcentration system may be
used in conjunction with the IC/PCR to increase sensitivity for trace
levels of Cr+6.
11.5.3.2 The preconcentration is accomplished by selectively
retaining the analyte on a solid absorbent, followed by removal of the
analyte from the absorbent (consult instrument manual).
11.5.3.3 For a manual system, position the injection valve so that
the eluent displaces the concentrated Cr+\6\ sample,
transferring it from the preconcentration column and onto the IC anion
separation column.
11.6 IC/PCR Sample Analyses.
11.6.1 The IC/PCR analysis is applicable for hexavalent chromium
measurements only.
11.6.2 IC/PCR Blanks. Two types of blanks are required for the IC/
PCR analysis.
11.6.2.1 Calibration Blank. The calibration blank is used in
establishing the analytical curve. For the calibration blank, use
either 0.1 N NaOH or 0.1 N NaHCO3, whichever is used for the
impinger solution. The calibration blank can be prepared fresh in the
laboratory; it does not have to be prepared from the same batch of
absorbing solution that is used in the field.
11.6.2.2 Field Reagent Blank. An aliquot of the 0.1 N NaOH
solution or the 0.1 N NaHCO3 solution prepared in Section
7.1.2 is collected for the field reagent blank. The field reagent blank
is used to assess possible contamination resulting from processing the
sample.
11.6.3 Stabilized Baseline. Prior to sample analysis, establish a
stable baseline with the detector set at the required attenuation by
setting the eluent and post-column reagent flow rates according to the
manufacturers recommendations.
Note: As long as the ratio of eluent flow rate to PCR flow rate
remains constant, the standard curve should remain linear. Inject a
sample of reagent water to ensure that no Cr+6 appears in
the water blank.
11.6.4 Sample Injection Loop. Size of injection loop is based on
standard/sample concentrations and the selected attenuator setting.
11.6.4.1 A 50-L loop is normally sufficient for most
higher concentrations.
11.6.4.2 The sample volume used to load the injection loop should
be at least 10 times the loop size so that all tubing in contact with
the sample is thoroughly flushed with the new sample to prevent cross
contamination.
11.6.5 IC/PCR Instrument Calibration.
11.6.5.1 First, inject the calibration standards prepared, as
described in
[[Page 62255]]
Section 7.3.8 to correspond to the appropriate concentration range,
starting with the lowest standard first.
11.6.5.2 Check the performance of the instrument and verify the
calibration using data gathered from analyses of laboratory blanks,
calibration standards, and a quality control sample.
11.6.5.3 Verify the calibration by analyzing a calibration
reference standard. If the measured concentration exceeds the
established value by more than 10 percent, perform a second analysis.
If the measured concentration still exceeds the established value by
more than 10 percent, terminate the analysis until the problem can be
identified and corrected.
11.6.6 IC/PCR Instrument Operation.
11.6.6.1 Inject the calibration reference standard (as described
in Section 9.3.1), followed by the field reagent blank (Section 8.2.4),
and the field samples.
11.6.6.1.1 Standards (and QC standards) and samples are injected
into the sample loop of the desired size (use a larger size loop for
greater sensitivity). The Cr+6 is collected on the resin bed
of the column.
11.6.6.1.2 After separation from other sample components, the
Cr+6 forms a specific complex in the post-column reactor
with the DPC reaction solution, and the complex is detected by visible
absorbance at a maximum wavelength of 540 nm.
11.6.6.1.3 The amount of absorbance measured is proportional to
the concentration of the Cr+6 complex formed.
11.6.6.1.4 The IC retention time and the absorbance of the
Cr+6 complex with known Cr+6 standards analyzed
under identical conditions must be compared to provide both qualitative
and quantitative analyses.
11.6.6.1.5 If a sample peak appears near the expected retention
time of the Cr+6 ion, spike the sample according to Section
9.3.4 to verify peak identity.
11.6.7 IC/PCR Operational Quality Control Procedures.
11.6.7.1 Samples should be at a pH 8.5 for NaOH and
8.0 if using NaHCO3; document any discrepancies.
11.6.7.2 Refrigerated samples should be allowed to equilibrate to
ambient temperature prior to preparation and analysis.
11.6.7.3 Repeat the injection of the calibration standards at the
end of the analytical run to assess instrument drift. Measure areas or
heights of the Cr+6/DPC complex chromatogram peaks.
11.6.7.4 To ensure the precision of the sample injection (manual
or autosampler), the response for the second set of injected standards
must be within 10 percent of the average response.
11.6.7.5 If the 10 percent criteria duplicate injection cannot be
achieved, identify the source of the problem and rerun the calibration
standards.
11.6.7.6 Use peak areas or peak heights from the injections of
calibration standards to generate a linear calibration curve. From the
calibration curve, determine the concentrations of the field samples.
11.6.8 IC/PCR Sample Dilution.
11.6.8.1 Samples having concentrations higher than the established
calibration range must be diluted into the calibration range and re-
analyzed.
11.6.8.2 If dilutions are performed, the appropriate factors must
be applied to sample measurement results.
11.6.9 Reporting Analytical Results. Results should be reported in
g Cr+6/mL using three significant figures. Field
sample volumes (mL) must be reported also.
12.0 Data Analysis and Calculations
12.1 Pretest Calculations.
12.1.1 Pretest Protocol (Site Test Plan).
12.1.1.1 The pretest protocol should define and address the test
data quality objectives (DQOs), with all assumptions, that will be
required by the end user (enforcement authority); what data are needed?
why are the data needed? how will the data be used? what are method
detection limits? and what are estimated target analyte levels for the
following test parameters.
12.1.1.1.1 Estimated source concentration for total chromium and/
or Cr+6.
12.1.1.1.2 Estimated minimum sampling time and/or volume required
to meet method detection limit requirements (Appendix B 40 CFR Part
136) for measurement of total chromium and/or Cr+6.
12.1.1.1.3 Demonstrate that planned sampling parameters will meet
DQOs. The protocol must demonstrate that the planned sampling
parameters calculated by the tester will meet the needs of the source
and the enforcement authority.
12.1.1.2 The pre-test protocol should include information on
equipment, logistics, personnel, process operation, and other resources
necessary for an efficient and coordinated test.
12.1.1.3 At a minimum, the pre-test protocol should identify and
be approved by the source, the tester, the analytical laboratory, and
the regulatory enforcement authority. The tester should not proceed
with the compliance testing before obtaining approval from the
enforcement authority.
12.1.2 Post Test Calculations.
12.1.2.1 Perform the calculations, retaining one extra decimal
figure beyond that of the acquired data. Round off figures after final
calculations.
12.1.2.2 Nomenclature.
CS = Concentration of Cr in sample solution, g Cr/
mL.
Ccr = Concentration of Cr in stack gas, dry basis, corrected
to standard conditions, mg/dscm.
D = Digestion factor, dimension less.
F = Dilution factor, dimension less.
MCr = Total Cr in each sample, g.
Vad = Volume of sample aliquot after digestion, mL.
Vaf = Volume of sample aliquot after dilution, mL.
Vbd = Volume of sample aliquot submitted to digestion, mL.
Vbf = Volume of sample aliquot before dilution, mL.
VmL = Volume of impinger contents plus rinses, mL.
Vm(std) = Volume of gas sample measured by the dry gas
meter, corrected to standard conditions, dscm.
12.1.2.3 Dilution Factor. The dilution factor is the ratio of the
volume of sample aliquot after dilution to the volume before dilution.
This ratio is given by the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.573
12.1.2.4 Digestion Factor. The digestion factor is the ratio of
the volume of sample aliquot after digestion to the volume before
digestion. This ratio is given by Equation 306-2.
[[Page 62256]]
[GRAPHIC] [TIFF OMITTED] TR17OC00.574
12.1.2.5 Total Cr in Sample. Calculate MCr, the total g
Cr in each sample, using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.575
12.1.2.6 Average Dry Gas Meter Temperature and Average Orifice
Pressure Drop. Same as Method 5.
12.1.2.7 Dry Gas Volume, Volume of Water Vapor, Moisture Content.
Same as Method 5.
12.1.2.8 Cr Emission Concentration (CCr). Calculate
CCr, the Cr concentration in the stack gas, in mg/dscm on a
dry basis, corrected to standard conditions using the following
equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.576
12.1.2.9 Isokinetic Variation, Acceptable Results. Same as Method
5.
13.0 Method Performance
13.1 Range. The recommended working range for all of the three
analytical techniques starts at five times the analytical detection
limit (see also Section 13.2.2). The upper limit of all three
techniques can be extended indefinitely by appropriate dilution.
13.2 Sensitivity.
13.2.1 Analytical Sensitivity. The estimated instrumental
detection limits listed are provided as a guide for an instrumental
limit. The actual method detection limits are sample and instrument
dependent and may vary as the sample matrix varies.
13.2.1.2 ICP Analytical Sensitivity. The minimum estimated
detection limits for ICP, as reported in Method 6010A and the recently
revised Method 6010B of SW-846 (Reference 1), are 7.0 g Cr/L
and 4.7 g Cr/L, respectively.
13.2.1.3 GFAAS Analytical Sensitivity. The minimum estimated
detection limit for GFAAS, as reported in Methods 7000A and 7191 of SW-
846 (Reference 1), is 1 g Cr/L.
13.2.1.4 IC/PCR Analytical Sensitivity. The minimum detection
limit for IC/PCR with a preconcentrator, as reported in Methods 0061
and 7199 of SW-846 (Reference 1), is 0.05 g Cr\+6\/L.
1.3.2.1.5 Determination of Detection Limits. The laboratory
performing the Cr\+6\ measurements must determine the method detection
limit on a quarterly basis using a suitable procedure such as that
found in 40 CFR, Part 136, Appendix B. The determination should be made
on samples in the appropriate alkaline matrix. Normally this involves
the preparation (if applicable) and consecutive measurement of seven
(7) separate aliquots of a sample with a concentration 5 times the
expected detection limit. The detection limit is 3.14 times the
standard deviation of these results.
13.2.2 In-stack Sensitivity. The in-stack sensitivity depends upon
the analytical detection limit, the volume of stack gas sampled, the
total volume of the impinger absorbing solution plus the rinses, and,
in some cases, dilution or concentration factors from sample
preparation. Using the analytical detection limits given in Sections
13.2.1.1, 13.2.1.2, and 13.2.1.3; a stack gas sample volume of 1.7
dscm; a total liquid sample volume of 500 mL; and the digestion
concentration factor of 1/2 for the GFAAS analysis; the corresponding
in-stack detection limits are 0.0014 mg Cr/dscm to 0.0021 mg Cr/dscm
for ICP, 0.00015 mg Cr/dscm for GFAAS, and 0.000015 mg Cr\+6\/dscm for
IC/PCR with preconcentration.
Note: It is recommended that the concentration of Cr in the
analytical solutions be at least five times the analytical detection
limit to optimize sensitivity in the analyses. Using this guideline
and the same assumptions for impinger sample volume, stack gas
sample volume, and the digestion concentration factor for the GFAAS
analysis (500 mL,1.7 dscm, and 1/2, respectively), the recommended
minimum stack concentrations for optimum sensitivity are 0.0068 mg
Cr/dscm to 0.0103 mg Cr/dscm for ICP, 0.00074 mg Cr/dscm for GFAAS,
and 0.000074 mg Cr\+6\/dscm for IC/PCR with preconcentration. If
required, the in-stack detection limits can be improved by either
increasing the stack gas sample volume, further reducing the volume
of the digested sample for GFAAS, improving the analytical detection
limits, or any combination of the three.
13.3 Precision.
13.3.1 The following precision data have been reported for the
three analytical methods. In each case, when the sampling precision is
combined with the reported analytical precision, the resulting overall
precision may decrease.
13.3.2 Bias data is also reported for GFAAS.
13.4 ICP Precision.
13.4.1 As reported in Method 6010B of SW-846 (Reference 1), in an
EPA round-robin Phase 1 study, seven laboratories applied the ICP
technique to acid/distilled water matrices that had been spiked with
various metal concentrates. For true values of 10, 50, and 150
g Cr/L; the mean reported values were 10, 50, and 149
g Cr/L; and the mean percent relative standard deviations were
18, 3.3, and 3.8 percent, respectively.
13.4.2 In another multi laboratory study cited in Method 6010B, a
mean relative standard of 8.2 percent was reported for an aqueous
sample concentration of approximately 3750 g Cr/L.
13.5 GFAAS Precision. As reported in Method 7191 of SW-846
(Reference 1), in a single laboratory (EMSL), using Cincinnati, Ohio
tap water spiked at concentrations of 19, 48, and 77 g Cr/L,
the standard deviations were 0.1, 0.2, and
0.8, respectively. Recoveries at these levels were 97
percent, 101 percent, and 102 percent, respectively.
13.6 IC/PCR Precision. As reported in Methods 0061 and 7199 of SW-
846 (Reference 1), the precision of IC/PCR with sample preconcentration
is 5 to 10 percent. The overall precision for
[[Page 62257]]
sewage sludge incinerators emitting 120 ng/dscm of Cr+\6\
and 3.5 g/dscm of total Cr was 25 percent and 9 percent,
respectively; and for hazardous waste incinerators emitting 300 ng/dscm
of C+\6\ the precision was 20 percent.
14.0 Pollution Prevention
14.1 The only materials used in this method that could be
considered pollutants are the chromium standards used for instrument
calibration and acids used in the cleaning of the collection and
measurement containers/labware, in the preparation of standards, and in
the acid digestion of samples. Both reagents can be stored in the same
waste container.
14.2 Cleaning solutions containing acids should be prepared in
volumes consistent with use to minimize the disposal of excessive
volumes of acid.
14.3 To the extent possible, the containers/vessels used to
collect and prepare samples should be cleaned and reused to minimize
the generation of solid waste.
15.0 Waste Management
15.1 It is the responsibility of the laboratory and the sampling
team to comply with all federal, state, and local regulations governing
waste management, particularly the discharge regulations, hazardous
waste identification rules, and land disposal restrictions; and to
protect the air, water, and land by minimizing and controlling all
releases from field operations.
15.2 For further information on waste management, consult The
Waste Management Manual for Laboratory Personnel and Less is Better--
Laboratory Chemical Management for Waste Reduction, available from the
American Chemical Society's Department of Government Relations and
Science Policy, 1155 16th Street NW, Washington, DC 20036.
16.0 References
1. ``Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods, SW-846, Third Edition,'' as amended by Updates I, II, IIA,
IIB, and III. Document No. 955-001-000001. Available from
Superintendent of Documents, U.S. Government Printing Office,
Washington, DC, November 1986.
2. Cox, X.B., R.W. Linton, and F.E. Butler. Determination of
Chromium Speciation in Environmental Particles--A Multi-technique
Study of Ferrochrome Smelter Dust. Accepted for publication in
Environmental Science and Technology.
3. Same as Section 17.0 of Method 5, References 2, 3, 4, 5, and
7.
4. California Air Resources Board, ``Determination of Total
Chromium and Hexavalent Chromium Emissions from Stationary
Sources.'' Method 425, September 12, 1990.
5. The Merck Index. Eleventh Edition. Merck & Co., Inc., 1989.
6. Walpole, R.E., and R.H. Myers. ``Probability and Statistics
for Scientists and Engineering.'' 3rd Edition. MacMillan Publishing
Co., NewYork, N.Y., 1985.
BILLING CODE 6560-50-C
[[Page 62258]]
17.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.577
[[Page 62259]]
[GRAPHIC] [TIFF OMITTED] TR17OC00.578
BILLING CODE 6560-50-C
[[Page 62260]]
Method 306A--Determination of Chromium Emissions From Decorative
and Hard Chromium Electroplating and Chromium Anodizing Operations
Note: This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g., sampling and
analytical) essential to its performance. Some material is
incorporated by reference from other methods in 40 CFR Part 60,
Appendix A and in this part. Therefore, to obtain reliable results,
persons using this method should have a thorough knowledge of at
least Methods 5 and 306.
1.0 Scope and Application
1.1 Analyte. Chromium. CAS Number (7440-47-3).
1.2 Applicability.
1.2.1 This method applies to the determination of chromium (Cr) in
emissions from decorative and hard chromium electroplating facilities,
chromium anodizing operations, and continuous chromium plating at iron
and steel facilities. The method is less expensive and less complex to
conduct than Method 306. Correctly applied, the precision and bias of
the sample results should be comparable to those obtained with the
isokinetic Method 306. This method is applicable for the determination
of air emissions under nominal ambient moisture, temperature, and
pressure conditions.
1.2.2 The method is also applicable to electroplating and
anodizing sources controlled by wet scrubbers.
1.3 Data Quality Objectives.
1.3.1 Pretest Protocol.
1.3.1.1 The pretest protocol should define and address the test
data quality objectives (DQOs), with all assumptions, that will be
required by the end user (enforcement authority); what data are needed?
why are the data needed? how will data be used? what are method
detection limits? and what are estimated target analyte levels for the
following test parameters.
1.3.1.1.1 Estimated source concentration for total chromium and/or
Cr\+6\.
1.3.1.1.2 Estimated minimum sampling time and/or volume required
to meet method detection limit requirements (Appendix B 40 CFR Part
136) for measurement of total chromium and/or Cr\+6\.
1.3.1.1.3 Demonstrate that planned sampling parameters will meet
DQOs. The protocol must demonstrate that the planned sampling
parameters calculated by the tester will meet the needs of the source
and the enforcement authority.
1.3.1.2 The pre-test protocol should include information on
equipment, logistics, personnel, process operation, and other resources
necessary for an efficient and coordinated performance test.
1.3.1.3 At a minimum, the pre-test protocol should identify and be
approved by the source, the tester, the analytical laboratory, and the
regulatory enforcement authority. The tester should not proceed with
the compliance testing before obtaining approval from the enforcement
authority.
2.0 Summary of Method
2.1 Sampling.
2.1.1 An emission sample is extracted from the source at a
constant sampling rate determined by a critical orifice and collected
in a sampling train composed of a probe and impingers. The proportional
sampling time at the cross sectional traverse points is varied
according to the stack gas velocity at each point. The total sample
time must be at least two hours.
2.1.2 The chromium emission concentration is determined by the
same analytical procedures described in Method 306: inductively-coupled
plasma emission spectrometry (ICP), graphite furnace atomic absorption
spectrometry (GFAAS), or ion chromatography with a post-column reactor
(IC/PCR).
2.1.2.1 Total chromium samples with high chromium concentrations
(35 g/L) may be analyzed using inductively coupled
plasma emission spectrometry (ICP) at 267.72 nm.
Note: The ICP analysis is applicable for this method only when
the solution analyzed has a Cr concentration greater than or equal
to 35 g/L or five times the method detection limit as
determined according to Appendix B in 40 CFR Part 136.
2.1.2.2 Alternatively, when lower total chromium concentrations
(35 g/L) are encountered, a portion of the alkaline sample
solution may be digested with nitric acid and analyzed by graphite
furnace atomic absorption spectroscopy (GFAAS) at 357.9 nm.
2.1.2.3 If it is desirable to determine hexavalent chromium
(Cr\+6\) emissions, the samples may be analyzed using an ion
chromatograph equipped with a post-column reactor (IC/PCR) and a
visible wavelength detector. To increase sensitivity for trace levels
of Cr\+6\, a preconcentration system may be used in conjunction with
the IC/PCR.
3.0 Definitions
3.1 Total Chromium--measured chromium content that includes both
major chromium oxidation states (Cr+3, Cr+6).
3.2 May--Implies an optional operation.
3.3 Digestion--The analytical operation involving the complete (or
nearly complete) dissolution of the sample in order to ensure the
complete solubilization of the element (analyte) to be measured.
3.4 Interferences--Physical, chemical, or spectral phenomena that
may produce a high or low bias in the analytical result.
3.5 Analytical System--All components of the analytical process
including the sample digestion and measurement apparatus.
3.6 Sample Recovery--The quantitative transfer of sample from the
collection apparatus to the sample preparation (digestion, etc.)
apparatus. This term should not be confused with analytical recovery.
4.0 Interferences
4.1 Same as in Method 306, Section 4.0.
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method does not purport to address
all of the safety issues associated with its use. It is the
responsibility of the user to establish appropriate safety and health
practices and to determine the applicability of regulatory limitations
prior to performing this test method.
5.2 Chromium and some chromium compounds have been listed as
carcinogens although Chromium (III) compounds show little or no
toxicity. Chromium is a skin and respiratory irritant.
6.0 Equipment and Supplies
Note: Mention of trade names or specific products does not
constitute endorsement by the Environmental Protection Agency.
6.1 Sampling Train. A schematic of the sampling train is shown in
Figure 306A-1. The individual components of the train are available
commercially, however, some fabrication and assembly are required.
6.1.1 Probe Nozzle/Tubing and Sheath.
6.1.1.1 Use approximately 6.4-mm (\1/4\-in.) inside diameter (ID)
glass or rigid plastic tubing approximately 20 cm (8 in.) in length
with a short 90 degree bend at one end to form the sampling nozzle.
Grind a slight taper on the nozzle end before making the bend. Attach
the nozzle to flexible tubing of sufficient length to enable collection
of a sample from the stack.
6.1.1.2 Use a straight piece of larger diameter rigid tubing (such
as metal conduit or plastic water pipe) to form a sheath that begins
about 2.5 cm (1 in.) from the 90 deg. bend on the nozzle and
[[Page 62261]]
encases and supports the flexible tubing.
6.1.2 Type S Pitot Tube. Same as Method 2, Section 6.1 (40 CFR Part
60, Appendix A).
6.1.3 Temperature Sensor.
6.1.3.1 A thermocouple, liquid-filled bulb thermometer, bimetallic
thermometer, mercury-in-glass thermometer, or other sensor capable of
measuring temperature to within 1.5 percent of the minimum absolute
stack temperature.
6.1.3.2 The temperature sensor shall either be positioned near the
center of the stack, or be attached to the pitot tube as directed in
Section 6.3 of Method 2.
6.1.4 Sample Train Connectors.
6.1.4.1 Use thick wall flexible plastic tubing (polyethylene,
polypropylene, or polyvinyl chloride) 6.4-mm (\1/4\-in.)
to 9.5-mm (\3/8\-in.) ID to connect the train components.
6.1.4.2 A combination of rigid plastic tubing and thin wall
flexible tubing may be used as long as tubing walls do not collapse
when leak-checking the train. Metal tubing cannot be used.
6.1.5 Impingers. Three, one-quart capacity, glass canning jars
with vacuum seal lids, or three Greenburg-Smith (GS) design impingers
connected in series, or equivalent, may be used.
6.1.5.1 One-quart glass canning jar. Three separate jar containers
are required: (1) the first jar contains the absorbing solution; (2)
the second is empty and is used to collect any reagent carried over
from the first container; and (3) the third contains the desiccant
drying agent.
6.1.5.2 Canning Jar Connectors. The jar containers are connected
by leak-tight inlet and outlet tubes installed in the lids of each
container for assembly with the train. The tubes may be made of
6.4 mm (\1/4\-in.) ID glass or rigid plastic tubing. For
the inlet tube of the first impinger, heat the glass or plastic tubing
and draw until the tubing separates. Fabricate the necked tip to form
an orifice tip that is approximately 2.4 mm (\3/32\-in.) ID.
6.1.5.2.1 When assembling the first container, place the orifice
tip end of the tube approximately 4.8 mm (\3/16\-in.) above the inside
bottom of the jar.
6.1.5.2.2 For the second container, the inlet tube need not be
drawn and sized, but the tip should be approximately 25 mm (1 in.)
above the bottom of the jar.
6.1.5.2.3 The inlet tube of the third container should extend to
approximately 12.7 mm (\1/2\-in.) above the bottom of the jar.
6.1.5.2.4 Extend the outlet tube for each container approximately
50 mm (2 in.) above the jar lid and downward through the lid,
approximately 12.7 mm (\1/2\-in.) beneath the bottom of the lid.
6.1.5.3 Greenburg-Smith Impingers. Three separate impingers of the
Greenburg-Smith (GS) design as described in Section 6.0 of Method 5 are
required. The first GS impinger shall have a standard tip (orifice/
plate), and the second and third GS impingers shall be modified by
replacing the orifice/plate tube with a 13 mm (\1/2\-in.) ID glass
tube, having an unrestricted opening located 13 mm (\1/2\-in.) from the
bottom of the outer flask.
6.1.5.4 Greenburg-Smith Connectors. The GS impingers shall be
connected by leak-free ground glass ``U'' tube connectors or by leak-
free non-contaminating flexible tubing. The first impinger shall
contain the absorbing solution, the second is empty and the third
contains the desiccant drying agent.
6.1.6 Manometer. Inclined/vertical type, or equivalent device, as
described in Section 6.2 of Method 2 (40 CFR Part 60, Appendix A).
6.1.7 Critical Orifice. The critical orifice is a small
restriction in the sample line that is located upstream of the vacuum
pump. The orifice produces a constant sampling flow rate that is
approximately 0.021 cubic meters per minute (m3/min) or 0.75
cubic feet per minute (cfm).
6.1.7.1 The critical orifice can be constructed by sealing a 2.4-
mm (\3/32\-in.) ID brass tube approximately 14.3 mm (\9/16\-in.) in
length inside a second brass tube that is approximately 8 mm (\5/16\-
in.) ID and 14.3-mm (\9/16\-in.) in length .
6.1.7.2 Materials other than brass can be used to construct the
critical orifice as long as the flow through the sampling train can be
maintained at approximately 0.021 cubic meter per minute (0.75) cfm.
6.1.8 Connecting Hardware. Standard pipe and fittings, 9.5-mm (\3/
8\-in.), 6.4-mm (\1/4\-in.) or 3.2-mm (\1/8\-in.) ID, may be used to
assemble the vacuum pump, dry gas meter and other sampling train
components.
6.1.9 Vacuum Gauge. Capable of measuring approximately 760 mm
Hg (30 in. Hg) vacuum in 25.4 mm HG (1
in. Hg) increments. Locate vacuum gauge between the critical
orifice and the vacuum pump.
6.1.10 Pump Oiler. A glass oil reservoir with a wick mounted at
the vacuum pump inlet that lubricates the pump vanes. The oiler should
be an in-line type and not vented to the atmosphere. See EMTIC
Guideline Document No. GD-041.WPD for additional information.
6.1.11 Vacuum Pump. Gast Model 0522-V103-G18DX, or equivalent,
capable of delivering at least 1.5 cfm at 15 in. Hg vacuum.
6.1.12 Oil Trap/Muffler. An empty glass oil reservoir without wick
mounted at the pump outlet to control the pump noise and prevent oil
from reaching the dry gas meter.
6.1.13 By-pass Fine Adjust Valve (Optional). Needle valve assembly
6.4-mm (\1/4\-in.), Whitey 1 RF 4-A, or equivalent, that allows for
adjustment of the train vacuum.
6.1.13.1 A fine-adjustment valve is positioned in the optional
pump by-pass system that allows the gas flow to recirculate through the
pump. This by-pass system allows the tester to control/reduce the
maximum leak-check vacuum pressure produced by the pump.
6.1.13.1.1 The tester must conduct the post test leak check at a
vacuum equal to or greater than the maximum vacuum encountered during
the sampling run.
6.1.13.1.2 The pump by-pass assembly is not required, but is
recommended if the tester intends to leak-check the 306A train at the
vacuum experienced during a run.
6.1.14 Dry Gas Meter. An Equimeter Model 110 test meter or,
equivalent with temperature sensor(s) installed (inlet/outlet) to
monitor the meter temperature. If only one temperature sensor is
installed, locate the sensor at the outlet side of the meter. The dry
gas meter must be capable of measuring the gaseous volume to within
2% of the true volume.
Note: The Method 306 sampling train is also commercially
available and may be used to perform the Method 306A tests. The
sampling train may be assembled as specified in Method 306A with the
sampling rate being operated at the delta H@ specified
for the calibrated orifice located in the meter box. The Method 306
train is then operated as described in Method 306A.
6.2 Barometer. Mercury aneroid barometer, or other barometer
equivalent, capable of measuring atmospheric pressure to within
2.5 mm Hg (0.1 in. Hg).
6.2.1 A preliminary check of the barometer shall be made against a
mercury-in-glass reference barometer or its equivalent.
6.2.2 Tester may elect to obtain the absolute barometric pressure
from a nearby National Weather Service station.
6.2.2.1 The station value (which is the absolute barometric
pressure) must be adjusted for elevation differences between the
weather station and the sampling location. Either subtract 2.5
[[Page 62262]]
mm Hg (0.1 in. Hg) from the station value per 30
m (100 ft) of elevation increase or add the same for an elevation
decrease.
6.2.2.2 If the field barometer cannot be adjusted to agree within
0.1 in. Hg of the reference barometric, repair or discard
the unit. The barometer pressure measurement shall be recorded on the
sampling data sheet.
6.3 Sample Recovery. Same as Method 5, Section 6.2 (40 CFR Part
60, Appendix A), with the following exceptions:
6.3.1 Probe-Liner and Probe-Nozzle Brushes. Brushes are not
necessary for sample recovery. If a probe brush is used, it must be
non-metallic.
6.3.2 Wash Bottles. Polyethylene wash bottle, for sample recovery
absorbing solution.
6.3.3 Sample Recovery Solution. Use 0.1 N NaOH or 0.1 N
NaHCO3, whichever is used as the impinger absorbing
solution, to replace the acetone.
6.3.4 Sample Storage Containers.
6.3.4.1 Glass Canning Jar. The first canning jar container of the
sampling train may serve as the sample shipping container. A new lid
and sealing plastic wrap shall be substituted for the container lid
assembly.
6.3.4.2 Polyethylene or Glass Containers. Transfer the Greenburg-
Smith impinger contents to precleaned polyethylene or glass containers.
The samples shall be stored and shipped in 250-mL, 500-mL or 1000-mL
polyethylene or glass containers with leak-free, non metal screw caps.
6.3.5 pH Indicator Strip, for Cr +6 Samples. pH
indicator strips, or equivalent, capable of determining the pH of
solutions between the range of 7 and 12, at 0.5 pH increments.
6.3.6 Plastic Storage Containers. Air tight containers to store
silica gel.
6.4 Analysis. Same as Method 306, Section 6.3.
7.0 Reagents and Standards.
Note: Unless otherwise indicated, all reagents shall conform to
the specifications established by the Committee on Analytical
Reagents of the American Chemical Society (ACS reagent grade). Where
such specifications are not available, use the best available grade.
It is recommended, but not required, that reagents be checked by the
appropriate analysis prior to field use to assure that contamination
is below the analytical detection limit for the ICP or GFAAS total
chromium analysis; and that contamination is below the analytical
detection limit for Cr+6 using IC/PCR for direct
injection or, if selected, preconcentration.
7.1 Sampling.
7.1.1 Water. Reagent water that conforms to ASTM Specification
D1193 Type II (incorporated by reference see Sec. 63.14). All
references to water in the method refer to reagent water unless
otherwise specified. It is recommended that water blanks be checked
prior to preparing the sampling reagents to ensure that the Cr content
is less than three (3) times the anticipated detection limit of the
analytical method.
7.1.2 Sodium Hydroxide (NaOH) Absorbing Solution, 0.1 N. Dissolve
4.0 g of sodium hydroxide in 1 liter of water to obtain a pH of
approximately 8.5.
7.1.3 Sodium Bicarbonate (NaHCO3) Absorbing Solution,
0.1 N. Dissolve approximately 8.5 g of sodium bicarbonate in 1 liter of
water to obtain a pH of approximately 8.3.
7.1.4 Chromium Contamination.
7.1.4.1 The absorbing solution shall not exceed the QC criteria
noted in Method 306, Section 7.1.1 (3 times the instrument
detection limit).
7.1.4.2 When the Cr+6 content in the field samples
exceeds the blank concentration by at least a factor of ten (10),
Cr+\6\ blank levels 10 times the detection limit
will be allowed.
Note: At sources with high concentrations of acids and/or
SO2, the concentration of NaOH or NaHCO3
should be 0.5 N to insure that the pH of the solution
remains at or above 8.5 for NaOH and 8.0 for NaHCO3
during and after sampling.
7.1.3 Desiccant. Silica Gel, 6-16 mesh, indicating type.
Alternatively, other types of desiccants may be used, subject to the
approval of the Administrator.
7.2 Sample Recovery. Same as Method 306, Section 7.2.
7.3 Sample Preparation and Analysis. Same as Method 306, Section
7.3.
7.4 Glassware Cleaning Reagents. Same as Method 306, Section 7.4.
7.5 Quality Assurance Audit Samples.
7.5.1 It is recommended, but not required, that a performance
audit sample be analyzed in conjunction with the field samples. The
audit sample should be in a suitable sample matrix at a concentration
similar to the actual field samples.
7.5.2 When making compliance determinations, and upon
availability, audit samples may be obtained from the appropriate EPA
regional Office or from the responsible enforcement authority and
analyzed in conjunction with the field samples.
Note: The responsible enforcement authority should be notified
at least 30 days prior to the test date to allow sufficient time for
the audit sample to be delivered.
8.0 Sample Collection, Recovery, Preservation, Holding Times, Storage,
and Transport
Note: Prior to sample collection, consideration should be given
as to the type of analysis (Cr+6 or total Cr) that will
be performed. Deciding which analysis will be performed will enable
the tester to determine which appropriate sample recovery and
storage procedures will be required to process the sample.
8.1 Sample Collection.
8.1.1 Pretest Preparation.
8.1.1.1 Selection of Measurement Site. Locate the sampling ports
as specified in Section 11.0 of Method 1 (40 CFR Part 60, Appendix A).
8.1.1.2 Location of Traverse Points.
8.1.1.2.1 Locate the traverse points as specified in Section 11.0
of Method 1 (40 CFR Part 60, Appendix A). Use a total of 24 sampling
points for round ducts and 24 or 25 points for rectangular ducts. Mark
the pitot and sampling probe to identify the sample traversing points.
8.1.1.2.2 For round ducts less than 12 inches in diameter, use a
total of 16 points.
8.1.1.3 Velocity Pressure Traverse. Perform an initial velocity
traverse before obtaining samples. The Figure 306A-2 data sheet may be
used to record velocity traverse data.
8.1.1.3.1 To demonstrate that the flow rate is constant over
several days of testing, perform complete traverses at the beginning
and end of each day's test effort, and calculate the deviation of the
flow rate for each daily period. The beginning and end flow rates are
considered constant if the deviation does not exceed 10 percent. If the
flow rate exceeds the 10 percent criteria, either correct the
inconsistent flow rate problem, or obtain the Administrator's approval
for the test results.
8.1.1.3.2 Perform traverses as specified in Section 8.0 of Method
2, but record only the p (velocity pressure) values for each
sampling point. If a mass emission rate is desired, stack velocity
pressures shall be recorded before and after each test, and an average
stack velocity pressure determined for the testing period.
8.1.1.4 Verification of Absence of Cyclonic Flow. Check for
cyclonic flow during the initial traverse to verify that it does not
exist. Perform the cyclonic flow check as specified in Section 11.4 of
Method 1 (40 CFR Part 60, Appendix A).
8.1.1.4.1 If cyclonic flow is present, verify that the absolute
average angle of the tangential flow does not exceed 20 degrees. If the
average value exceeds 20 degrees at the sampling location, the flow
condition in the stack is unacceptable for testing.
8.1.1.4.2 Alternative procedures, subject to approval of the
Administrator,
[[Page 62263]]
e.g., installing straightening vanes to eliminate the cyclonic flow,
must be implemented prior to conducting the testing.
8.1.1.5 Stack Gas Moisture Measurements. Not required. Measuring
the moisture content is optional when a mass emission rate is to be
calculated.
8.1.1.5.1 The tester may elect to either measure the actual stack
gas moisture during the sampling run or utilize a nominal moisture
value of 2 percent.
8.1.1.5.2 For additional information on determining sampling train
moisture, please refer to Method 4 (40 CFR Part 60, Appendix A).
8.1.1.6 Stack Temperature Measurements. If a mass emission rate is
to be calculated, a temperature sensor must be placed either near the
center of the stack, or attached to the pitot tube as described in
Section 8.3 of Method 2. Stack temperature measurements, shall be
recorded before and after each test, and an average stack temperature
determined for the testing period.
8.1.1.7 Point Sampling Times. Since the sampling rate of the train
(0.75 cfm) is maintained constant by the critical orifice, it is
necessary to calculate specific sampling times for each traverse point
in order to obtain a proportional sample.
8.1.1.7.1 If the sampling period (3 runs) is to be completed in a
single day, the point sampling times shall be calculated only once.
8.1.1.7.2 If the sampling period is to occur over several days,
the sampling times must be calculated daily using the initial velocity
pressure data recorded for that day. Determine the average of the
p values obtained during the velocity traverse (Figure 306A-
2).
8.1.1.7.3 If the stack diameter is less than 12 inches, use 7.5
minutes in place of 5 minutes in the equation and 16 sampling points
instead of 24 or 25 points. Calculate the sampling times for each
traverse point using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.579
Where:
n = Sampling point number.
p = Average pressure differential across pitot tube, mm
H2O (in. H2O).
Pavg = Average of p values, mm
H2O (in. H2O).
Note: Convert the decimal fractions for minutes to seconds.
8.1.1.8 Pretest Preparation. It is recommended, but not required,
that all items which will be in contact with the sample be cleaned
prior to performing the testing to avoid possible sample contamination
(positive chromium bias). These items include, but are not limited to:
Sampling probe, connecting tubing, impingers, and jar containers.
8.1.1.8.1 Sample train components should be: (1) Rinsed with hot
tap water; (2) washed with hot soapy water; (3) rinsed with tap water;
(4) rinsed with reagent water; (5) soaked in a 10 percent (v/v) nitric
acid solution for at least four hours; and (6) rinsed throughly with
reagent water before use.
8.1.1.8.2 At a minimum, the tester should, rinse the probe,
connecting tubing, and first and second impingers twice with either 0.1
N sodium hydroxide (NaOH) or 0.1 N sodium bicarbonate
(NaHCO3) and discard the rinse solution.
8.1.1.8.3 If separate sample shipping containers are to be used,
these also should be precleaned using the specified cleaning
procedures.
8.1.1.9 Preparation of Sampling Train. Assemble the sampling train
as shown in Figure 306A-1. Secure the nozzle-liner assembly to the
outer sheath to prevent movement when sampling.
8.1.1.9.1 Place 250 mL of 0.1 N NaOH or 0.1 N NaHCO3
absorbing solution into the first jar container or impinger. The second
jar/impinger is to remain empty. Place 6 to 16 mesh indicating silica
gel, or equivalent desiccant into the third jar/impinger until the
container is half full ( 300 to 400 g).
8.1.1.9.2 Place a small cotton ball in the outlet exit tube of the
third jar to collect small silica gel particles that may dislodge and
impair the pump and/or gas meter.
8.1.1.10 Pretest Leak-Check. A pretest leak-check is recommended,
but not required. If the tester opts to conduct the pretest leak-check,
the following procedures shall be performed: (1) Place the jar/impinger
containers into an ice bath and wait 10 minutes for the ice to cool the
containers before performing the leak check and/or start sampling; (2)
to perform the leak check, seal the nozzle using a piece of clear
plastic wrap placed over the end of a finger and switch on the pump;
and (3) the train system leak rate should not exceed 0.02 cfm at a
vacuum of 380 mm Hg (15 in. Hg) or greater. If the leak rate does
exceed the 0.02 cfm requirement, identify and repair the leak area and
perform the leak check again.
Note: Use caution when releasing the vacuum following the leak
check. Always allow air to slowly flow through the nozzle end of the
train system while the pump is still operating. Switching off the
pump with vacuum on the system may result in the silica gel being
pulled into the second jar container.
8.1.1.11 Leak-Checks During Sample Run. If, during the sampling
run, a component (e.g., jar container) exchange becomes necessary, a
leak-check shall be conducted immediately before the component exchange
is made. The leak-check shall be performed according to the procedure
outlined in Section 8.1.1.10 of this method. If the leakage rate is
found to be 0.02 cfm at the maximum operating vacuum, the
results are acceptable. If, however, a higher leak rate is obtained,
either record the leakage rate and correct the sample volume as shown
in Section 12.3 of Method 5 or void the sample and initiate a
replacement run. Following the component change, leak-checks are
optional, but are recommended as are the pretest leak-checks.
8.1.1.12 Post Test Leak Check. Remove the probe assembly and
flexible tubing from the first jar/impinger container. Seal the inlet
tube of the first container using clear plastic wrap and switch on the
pump. The vacuum in the line between the pump and the critical orifice
must be 15 in. Hg. Record the vacuum gauge measurement along
with the leak rate observed on the train system.
8.1.1.12.1 If the leak rate does not exceed 0.02 cfm, the results
are acceptable and no sample volume correction is necessary.
8.1.1.12.2 If, however, a higher leak rate is obtained (>0.02
cfm), the tester shall either record the leakage rate and correct the
sample volume as shown in Section 12.3 of Method 5, or void the
sampling run and initiate a replacement run. After completing the
leak-check, slowly release the vacuum at the first
[[Page 62264]]
container while the pump is still operating. Afterwards, switch-off the
pump.
8.1.2 Sample Train Operation.
8.1.2.1 Data Recording. Record all pertinent process and sampling
data on the data sheet (see Figure 306A-3). Ensure that the process
operation is suitable for sample collection.
8.1.2.2 Starting the Test. Place the probe/nozzle into the duct at
the first sampling point and switch on the pump. Start the sampling
using the time interval calculated for the first point. When the first
point sampling time has been completed, move to the second point and
continue to sample for the time interval calculated for that point;
sample each point on the traverse in this manner. Maintain ice around
the sample containers during the run.
8.1.2.3 Critical Flow. The sample line between the critical
orifice and the pump must operate at a vacuum of 380 mm Hg
(15 in. Hg) in order for critical flow to be maintained.
This vacuum must be monitored and documented using the vacuum gauge
located between the critical orifice and the pump.
Note: Theoretically, critical flow for air occurs when the ratio
of the orifice outlet absolute pressure to the orifice inlet
absolute pressure is less than a factor of 0.53. This means that the
system vacuum should be at least 356 mm Hg (
14 in. Hg) at sea level and 305 mm Hg ( 12
in. Hg) at higher elevations.
8.1.2.4 Completion of Test.
8.1.2.4.1 Circular Stacks. Complete the first port traverse and
switch off the pump. Testers may opt to perform a leak-check between
the port changes to verify the leak rate however, this is not
mandatory. Move the sampling train to the next sampling port and repeat
the sequence. Be sure to record the final dry gas meter reading after
completing the test run. After performing the post test leak check,
disconnect the jar/impinger containers from the pump and meter assembly
and transport the probe, connecting tubing, and containers to the
sample recovery area.
8.1.2.4.2 Rectangle Stacks. Complete each port traverse as per the
instructions provided in 8.1.2.4.1.
Note: If an approximate mass emission rate is to be calculated,
measure and record the stack velocity pressure and temperature
before and after the test run.
8.2 Sample Recovery. After the train has been transferred to the
sample recovery area, disconnect the tubing that connects the jar/
impingers. The tester shall select either the total Cr or
Cr+\6\ sample recovery option. Samples to be analyzed for
both total Cr and Cr+\6\ shall be recovered using the
Cr+\6\ sample option (Section 8.2.2).
Note: Collect a reagent blank sample for each of the total Cr or
the Cr+\6\ analytical options. If both analyses (Cr and
Cr+\6\) are to be conducted on the samples, collect
separate reagent blanks for each analysis.
8.2.1 Total Cr Sample Option.
8.2.1.1 Shipping Container No. 1. The first jar container may
either be used to store and transport the sample, or if GS impingers
are used, samples may be stored and shipped in precleaned 250-mL, 500-
mL or 1000-mL polyethylene or glass bottles with leak-free, non-metal
screw caps.
8.2.1.1.1 Unscrew the lid from the first jar/impinger container.
8.2.1.1.2 Lift the inner tube assembly almost out of the
container, and using the wash bottle containing fresh absorbing
solution, rinse the outside of the tube that was immersed in the
container solution; rinse the inside of the tube as well, by rinsing
twice from the top of the tube down through the inner tube into the
container.
8.2.1.2 Recover the contents of the second jar/impinger container
by removing the lid and pouring any contents into the first shipping
container.
8.2.1.2.1 Rinse twice, using fresh absorbing solution, the inner
walls of the second container including the inside and outside of the
inner tube.
8.2.1.2.2 Rinse the connecting tubing between the first and second
sample containers with absorbing solution and place the rinses into the
first container.
8.2.1.3 Position the nozzle, probe and connecting plastic tubing
in a vertical position so that the tubing forms a ``U''.
8.2.1.3.1 Using the wash bottle, partially fill the tubing with
fresh absorbing solution. Raise and lower the end of the plastic tubing
several times to allow the solution to contact the internal surfaces.
Do not allow the solution to overflow or part of the sample will be
lost. Place the nozzle end of the probe over the mouth of the first
container and elevate the plastic tubing so that the solution flows
into the sample container.
8.2.1.3.2 Repeat the probe/tubing sample recovery procedure but
allow the solution to flow out the opposite end of the plastic tubing
into the sample container. Repeat the entire sample recovery procedure
once again.
8.2.1.4 Use approximately 200 to 300 mL of the 0.1 N NaOH or 0.1 N
NaHCO3 absorbing solution during the rinsing of the probe
nozzle, probe liner, sample containers, and connecting tubing.
8.2.1.5 Place a piece of clear plastic wrap over the mouth of the
sample jar to seal the shipping container. Use a standard lid and band
assembly to seal and secure the sample in the jar.
8.2.1.5.1 Label the jar clearly to identify its contents, sample
number and date.
8.2.1.5.2 Mark the height of the liquid level on the container to
identify any losses during shipping and handling.
8.2.1.5.3 Prepare a chain-of-custody sheet to accompany the sample
to the laboratory.
8.2.2 Cr+\6\ Sample Option.
8.2.2.1 Shipping Container No. 1. The first jar container may
either be used to store and transport the sample, or if GS impingers
are used, samples may be stored and shipped in precleaned 250-mL, 500-
mL or 1000-mL polyethylene or glass bottles with leak-free non-metal
screw caps.
8.2.2.1.1 Unscrew and remove the lid from the first jar container.
8.2.2.1.2 Measure and record the pH of the solution in the first
container by using a pH indicator strip. The pH of the solution must be
8.5 for NaOH and 8.0 for NaHCO3. If
not, discard the collected sample, increase the concentration of the
NaOH or NaHCO3 absorbing solution to 0.5 M and collect another air
emission sample.
8.2.2.2 After measuring the pH of the first container, follow
sample recovery procedures described in Sections 8.2.1.1 through
8.2.1.5.
Note: Since particulate matter is not usually present at
chromium electroplating and/or chromium anodizing facilities, it is
not necessary to filter the Cr+\6\ samples unless there
is observed sediment in the collected solutions. If it is necessary
to filter the Cr+\6\ solutions, please refer to the EPA
Method 0061, Determination of Hexavalent Chromium Emissions from
Stationary Sources, Section 7.4, Sample Preparation in SW-846 (see
Reference 5) for procedure.
8.2.3 Silica Gel Container. Observe the color of the indicating
silica gel to determine if it has been completely spent and make a
notation of its condition/color on the field data sheet. Do not use
water or other liquids to remove and transfer the silica gel.
8.2.4 Total Cr and/or Cr+\6\ Reagent Blank.
8.2.4.1 Shipping Container No. 2. Place approximately 500 mL of
the 0.1 N NaOH or 0.1 N NaHCO3 absorbing solution in a
precleaned, labeled sample container and include with the field samples
for analysis.
8.3 Sample Preservation, Storage, and Transport.
[[Page 62265]]
8.3.1 Total Cr Option. Samples that are to be analyzed for total
Cr need not be refrigerated.
8.3.2 Cr+\6\ Option. Samples that are to be analyzed
for Cr+\6\ must be shipped and stored at 4 deg.C
(40 deg.F).
Note: Allow Cr+\6\ samples to return to ambient
temperature prior to analysis.
8.4 Sample Holding Times.
8.4.1 Total Cr Option. Samples that are to be analyzed for total
chromium must be analyzed within 60 days of collection.
8.4.2 Cr+\6\ Option. Samples that are to be analyzed
for Cr+\6\ must be analyzed within 14 days of collection.
9.0 Quality Control
9.1 Same as Method 306, Section 9.0.
10.0 Calibration and Standardization
Note: Tester shall maintain a performance log of all calibration
results.
10.1 Pitot Tube. The Type S pitot tube assembly shall be
calibrated according to the procedures outlined in Section 10.1 of
Method 2.
10.2 Temperature Sensor. Use the procedure in Section 10.3 of
Method 2 to calibrate the in-stack temperature sensor.
10.3 Metering System.
10.3.1 Sample Train Dry Gas Meter Calibration. Calibrations may be
performed as described in Section 16.2 of Method 5 by either the
manufacturer, a firm who provides calibration services, or the tester.
10.3.2 Dry Gas Meter Calibration Coefficient (Ym). The
meter calibration coefficient (Ym) must be determined prior
to the initial use of the meter, and following each field test program.
If the dry gas meter is new, the manufacturer will have specified the
Ym value for the meter. This Ym value can be used
as the pretest value for the first test. For subsequent tests, the
tester must use the Ym value established during the pretest
calibration.
10.3.3 Calibration Orifice. The manufacturer may have included a
calibration orifice and a summary spreadsheet with the meter that may
be used for calibration purposes. The spreadsheet will provide data
necessary to determine the calibration for the orifice and meter
(standard cubic feet volume, sample time, etc.). These data were
produced when the initial Ym value was determined for the
meter.
10.3.4 Ym Meter Value Verification or Meter
Calibration.
10.3.4.1 The Ym meter value may be determined by
replacing the sampling train critical orifice with the calibration
orifice. Replace the critical orifice assembly by installing the
calibration orifice in the same location. The inlet side of the
calibration orifice is to be left open to the atmosphere and is not to
be reconnected to the sample train during the calibration procedure.
10.3.4.2 If the vacuum pump is cold, switch on the pump and allow
it to operate (become warm) for several minutes prior to starting the
calibration. After stopping the pump, record the initial dry gas meter
volume and meter temperature.
10.3.4.3 Perform the calibration for the number of minutes
specified by the manufacturer's data sheet (usually 5 minutes). Stop
the pump and record the final dry gas meter volume and temperature.
Subtract the start volume from the stop volume to obtain the
Vm and average the meter temperatures (tm).
10.3.5 Ym Value Calculation. Ym is the
calculated value for the dry gas meter. Calculate Ym using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.580
Where:
Pbar = Barometric pressure at meter, mm Hg, (in. Hg).
Pstd = Standard absolute pressure,
Metric = 760 mm Hg.
English = 29.92 in. Hg.
tm = Average dry gas meter temperature, deg.C, ( deg.F).
Tm = Absolute average dry gas meter temperature,
Metric deg.K = 273 + tm ( deg.C).
English deg.R = 460 + tm( deg.F).
Tstd = Standard absolute temperature,
Metric = 293 deg.K.
English = 528 deg.R.
Vm = Volume of gas sample as measured (actual) by dry gas
meter, dcm,(dcf).
Vm(std),mfg = Volume of gas sample measured by manufacture's
calibrated orifice and dry gas meter, corrected to standard conditions
(pressure/temperature) dscm (dscf).
Ym = Dry gas meter calibration factor, (dimensionless).
10.3.6 Ym Comparison. Compare the Ym value
provided by the manufacturer (Section 10.3.3) or the pretest
Ym value to the post test Ym value using the
following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.581
10.3.6.1 If this ratio is between 0.95 and 1.05, the designated
Ym value for the meter is acceptable for use in later
calculations.
10.3.6.1.1 If the value is outside the specified range, the test
series shall
[[Page 62266]]
either be: 1) voided and the samples discarded; or 2) calculations for
the test series shall be conducted using whichever meter coefficient
value (i.e., manufacturers's/pretest Ym value or post test
Ym value) produces the lowest sample volume.
10.3.6.1.2 If the post test dry gas meter Ym value
differs by more than 5% as compared to the pretest value, either
perform the calibration again to determine acceptability or return the
meter to the manufacturer for recalibration.
10.3.6.1.3 The calibration may also be conducted as specified in
Section 10.3 or Section 16.0 of Method 5 (40 CFR Part 60, Appendix A),
except that it is only necessary to check the calibration at one flow
rate of 0.75 cfm.
10.3.6.1.4 The calibration of the dry gas meter must be verified
after each field test program using the same procedures.
Note: The tester may elect to use the Ym post test
value for the next pretest Ym value; e.g., Test 1 post
test Ym value and Test 2 pretest Ym value
would be the same.
10.4 Barometer. Calibrate against a mercury barometer that has
been corrected for temperature and elevation.
10.5 ICP Spectrometer Calibration. Same as Method 306, Section
10.2.
10.6 GFAA Spectrometer Calibration. Same as Method 306, Section
10.3.
10.7 IC/PCR Calibration. Same as Method 306, Section 10.4.
11.0 Analytical Procedures
Note: The method determines the chromium concentration in
g Cr/mL. It is important that the analyst measure the
volume of the field sample prior to analyzing the sample. This will
allow for conversion of g Cr/mL to g Cr/sample.
11.1 Analysis. Refer to Method 306 for sample preparation and
analysis procedures.
12.0 Data Analysis and Calculations
12.1 Calculations. Perform the calculations, retaining one extra
decimal point beyond that of the acquired data. When reporting final
results, round number of figures consistent with the original data.
12.2 Nomenclature.
A = Cross-sectional area of stack, m2 (ft2).
Bws = Water vapor in gas stream, proportion by volume,
dimensionless (assume 2 percent moisture = 0.02).
Cp = Pitot tube coefficient; ``S'' type pitot coefficient
usually 0.840, dimensionless.
CS = Concentration of Cr in sample solution, g Cr/
mL.
CCr = Concentration of Cr in stack gas, dry basis, corrected
to standard conditions g/dscm (gr/dscf).
d = Diameter of stack, m (ft).
D = Digestion factor, dimensionless.
ER = Approximate mass emission rate, mg/hr (lb/hr).
F = Dilution factor, dimensionless.
L = Length of a square or rectangular duct, m (ft).
MCr = Total Cr in each sample, g (gr).
Ms = Molecular weight of wet stack gas, wet basis, g/g-mole,
(lb/lb-mole); in a nominal gas stream at 2% moisture the value is
28.62.
Pbar = Barometric pressure at sampling site, mm Hg (in. Hg).
Ps = Absolute stack gas pressure; in this case, usually the
same value as the barometric pressure, mm Hg (in. Hg).
Pstd = Standard absolute pressure:
Metric = 760 mm Hg.
English = 29.92 in. Hg.
Qstd = Average stack gas volumetric flow, dry, corrected to
standard conditions, dscm/hr (dscf/hr).
tm = Average dry gas meter temperature, deg.C ( deg.F).
Tm = Absolute average dry gas meter temperature:
Metric deg.K = 273 + tm ( deg.C).
English deg.R = 460 + tm( deg.F).
ts = Average stack temperature, deg.C ( deg.F).
Ts = Absolute average stack gas temperature: Metric deg.K =
273 + ts ( deg.C). English deg.R = 460 +
ts( deg.F).
Tstd = Standard absolute temperature: Metric = 293 deg.K.
English = 528 deg.R.
Vad = Volume of sample aliquot after digestion (mL).
Vaf = Volume of sample aliquot after dilution (mL).
Vbd = Volume of sample aliquot submitted to digestion (mL).
Vbf = Volume of sample aliquot before dilution (mL).
Vm = Volume of gas sample as measured (actual, dry) by dry
gas meter, dcm (dcf).
VmL = Volume of impinger contents plus rinses (mL).
Vm(std) = Volume of gas sample measured by the dry gas
meter, corrected to standard conditions (temperature/pressure), dscm
(dscf).
vs = Stack gas average velocity, calculated by Method 2,
Equation 2-9, m/sec (ft/sec).
W = Width of a square or rectangular duct, m (ft).
Ym = Dry gas meter calibration factor, (dimensionless).
p = Velocity head measured by the Type S pitot tube, cm
H2O (in. H2O).
pavg = Average of p values, mm
H2O (in. H2O).
12.3 Dilution Factor. The dilution factor is the ratio of the
volume of sample aliquot after dilution to the volume before dilution.
The dilution factor is usually calculated by the laboratory. This ratio
is derived by the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.582
12.4 Digestion Factor. The digestion factor is the ratio of the
volume of sample aliquot after digestion to the volume before
digestion. The digestion factor is usually calculated by the
laboratory. This ratio is derived by the following equation.
[GRAPHIC] [TIFF OMITTED] TR17OC00.583
[[Page 62267]]
12.5 Total Cr in Sample. Calculate MCr, the total
g Cr in each sample, using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.584
12.6 Dry Gas Volume. Correct the sample volume measured by the dry
gas meter to standard conditions (20 deg.C, 760 mm Hg or 68'F, 29.92
in. Hg) using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.585
Where:
K1 = Metric units--0.3855 deg.K/mm Hg.
English units--17.64 deg.R/in. Hg.
12.7 Cr Emission Concentration (CCr). Calculate
CCr, the Cr concentration in the stack gas, in g/
dscm (g/dscf) on a dry basis, corrected to standard
conditions, using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.586
Note: To convert g/dscm (g/dscf) to mg/dscm (mg/
dscf), divide by 1000.
12.8 Stack Gas Velocity.
12.8.1 Kp = Velocity equation constant:
[GRAPHIC] [TIFF OMITTED] TR17OC00.587
[GRAPHIC] [TIFF OMITTED] TR17OC00.588
12.8.2 Average Stack Gas Velocity.
[GRAPHIC] [TIFF OMITTED] TR17OC00.589
12.9 Cross sectional area of stack.
[GRAPHIC] [TIFF OMITTED] TR17OC00.591
12.10 Average Stack Gas Dry Volumetric Flow Rate.
Note: The emission rate may be based on a nominal stack moisture
content of 2 percent (0.02). To calculate an emission rate, the tester
may elect to use either the nominal stack gas moisture value or the
actual stack gas moisture collected during the sampling run.
Volumetric Flow Rate Equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.592
Where:
3600 = Conversion factor, sec/hr.
[GRAPHIC] [TIFF OMITTED] TR17OC00.593
Note: To convert Qstd from dscm/hr (dscf/hr) to dscm/
min (dscf/min), divide Qstd by 60.
12.11 Mass emission rate, mg/hr (lb/hr):
[[Page 62268]]
[GRAPHIC] [TIFF OMITTED] TR17OC00.594
[GRAPHIC] [TIFF OMITTED] TR17OC00.595
13.0 Method Performance
13.1 Range. The recommended working range for all of the three
analytical techniques starts at five times the analytical detection
limit (see also Method 306, Section 13.2.2). The upper limit of all
three techniques can be extended indefinitely by appropriate dilution.
13.2 Sensitivity.
13.2.1 Analytical Sensitivity. The estimated instrumental
detection limits listed are provided as a guide for an instrumental
limit. The actual method detection limits are sample and instrument
dependent and may vary as the sample matrix varies.
13.2.1.1 ICP Analytical Sensitivity. The minimum estimated
detection limits for ICP, as reported in Method 6010A and the recently
revised Method 6010B of SW-846 (Reference 1), are 7.0 g Cr/L
and 4.7 g Cr/L, respectively.
13.2.1.2 GFAAS Analytical Sensitivity. The minimum estimated
detection limit for GFAAS, as reported in Methods 7000A and 7191 of SW-
846 (Reference 1), is 1.0 g Cr/L.
13.2.1.3 IC/PCR Analytical Sensitivity. The minimum detection
limit for IC/PCR with a preconcentrator, as reported in Methods 0061
and 7199 of SW-846 (Reference 1), is 0.05 g Cr+6/L.
13.2.2 In-stack Sensitivity. The in-stack sensitivity depends upon
the analytical detection limit, the volume of stack gas sampled, and
the total volume of the impinger absorbing solution plus the rinses.
Using the analytical detection limits given in Sections 13.2.1.1,
13.2.1.2, and 13.2.1.3; a stack gas sample volume of 1.7 dscm; and a
total liquid sample volume of 500 mL; the corresponding in-stack
detection limits are 0.0014 mg Cr/dscm to 0.0021 mg Cr/dscm for ICP,
0.00029 mg Cr/dscm for GFAAS, and 0.000015 mg Cr+36/dscm for
IC/PCR with preconcentration.
Note: It is recommended that the concentration of Cr in the
analytical solutions be at least five times the analytical detection
limit to optimize sensitivity in the analyses. Using this guideline
and the same assumptions for impinger sample volume and stack gas
sample volume (500 mL and 1.7 dscm, respectively), the recommended
minimum stack concentrations for optimum sensitivity are 0.0068 mg
Cr/dscm to 0.0103 mg Cr/dscm for ICP, 0.0015 mg Cr/dscm for GFAAS,
and 0.000074 mg Cr+6 dscm for IC/PCR with
preconcentration. If required, the in-stack detection limits can be
improved by either increasing the sampling time, the stack gas
sample volume, reducing the volume of the digested sample for GFAAS,
improving the analytical detection limits, or any combination of the
three.
13.3 Precision.
13.3.1 The following precision data have been reported for the
three analytical methods. In each case, when the sampling precision is
combined with the reported analytical precision, the resulting overall
precision may decrease.
13.3.2 Bias data is also reported for GFAAS.
13.4 ICP Precision.
13.4.1 As reported in Method 6010B of SW-846 (Reference 1), in an
EPA round-robin Phase 1 study, seven laboratories applied the ICP
technique to acid/distilled water matrices that had been spiked with
various metal concentrates. For true values of 10, 50, and 150
g Cr/L; the mean reported values were 10, 50, and 149
g Cr/L; and the mean percent relative standard deviations were
18, 3.3, and 3.8 percent, respectively.
13.4.2 In another multilaboratory study cited in Method 6010B, a
mean relative standard of 8.2 percent was reported for an aqueous
sample concentration of approximately 3750 g Cr/L.
13.5 GFAAS Precision. As reported in Method 7191 of SW-846
(Reference 1), in a single laboratory (EMSL), using Cincinnati, Ohio
tap water spiked at concentrations of 19, 48, and 77 g Cr/L,
the standard deviations were 0.1, 0.2, and
0.8, respectively. Recoveries at these levels were 97
percent, 101 percent, and 102 percent, respectively.
13.6 IC/PCR Precision. As reported in Methods 0061 and 7199 of SW-
846 (Reference 1), the precision of IC/PCR with sample preconcentration
is 5 to 10 percent; the overall precision for sewage sludge
incinerators emitting 120 ng/dscm of Cr+6 and 3.5
g/dscm of total Cr is 25 percent and 9 percent, respectively;
and for hazardous waste incinerators emitting 300 ng/dscm of
Cr+6 the precision is 20 percent.
14.0 Pollution Prevention
14.1 The only materials used in this method that could be
considered pollutants are the chromium standards used for instrument
calibration and acids used in the cleaning of the collection and
measurement containers/labware, in the preparation of standards, and in
the acid digestion of samples. Both reagents can be stored in the same
waste container.
14.2 Cleaning solutions containing acids should be prepared in
volumes consistent with use to minimize the disposal of excessive
volumes of acid.
14.3 To the extent possible, the containers/vessels used to
collect and prepare samples should be cleaned and reused to minimize
the generation of solid waste.
15.0 Waste Management
15.1 It is the responsibility of the laboratory and the sampling
team to comply with all federal, state, and local regulations governing
waste management, particularly the discharge regulations, hazardous
waste identification rules, and land disposal restrictions; and to
protect the air, water, and land by minimizing and controlling all
releases from field operations.
15.2 For further information on waste management, consult The
Waste Management Manual for Laboratory Personnel and Less is Better-
Laboratory Chemical Management for Waste Reduction, available from the
American Chemical Society's Department of Government Relations and
Science Policy, 1155 16th Street NW, Washington, DC 20036.
16.0 References
1. F.R. Clay, Memo, Impinger Collection Efficiency--Mason Jars
vs. Greenburg-Smith Impingers, Dec. 1989.
2. Segall, R.R., W.G. DeWees, F.R. Clay, and J.W. Brown.
Development of Screening Methods for Use in Chromium Emissions
Measurement and Regulations Enforcement. In: Proceedings of the 1989
EPA/A&WMA International Symposium-Measurement of Toxic and Related
Air Pollutants, A&WMA Publication VIP-13, EPA Report No. 600/9-89-
060, p. 785.
3. Clay, F.R., Chromium Sampling Method. In: Proceedings of the
1990 EPA/A&WMA International Symposium-Measurement of Toxic and
Related Air Pollutants, A&WMA Publication VIP-17, EPA Report No.
600/9-90-026, p. 576.
4. Clay, F.R., Proposed Sampling Method 306A for the
Determination of Hexavalent Chromium Emissions from Electroplating
and Anodizing Facilities. In: Proceedings of the 1992 EPA/A&WMA
International Symposium-Measurement of Toxic and
[[Page 62269]]
Related Air Pollutants, A&WMA Publication VIP-25, EPA Report No.
600/R-92/131, p. 209.
5. Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods, SW-846, Third Edition as amended by Updates I, II, IIA,
IIB, and III. Document No. 955-001-000001. Available from
Superintendent of Documents, U.S. Government Printing Office,
Washington, DC, November 1986.
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Method 306B--Surface Tension Measurement for Tanks Used at
Decorative Chromium Electroplating and Chromium Anodizing
Facilities
Note: This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g., sampling and
analytical) essential to its performance. Some material is
incorporated by reference from other methods in 40 CFR Part 60,
Appendix A and in this part. Therefore, to obtain reliable results,
persons using this method should have a thorough knowledge of at
least Methods 5 and 306.
1.0 Scope and Application
1.1 Analyte. Not applicable.
1.2 Applicability. This method is applicable to all decorative
chromium plating and chromium anodizing operations, and continuous
chromium plating at iron and steel facilities where a wetting agent is
used in the tank as the primary mechanism for reducing emissions from
the surface of the plating solution.
2.0 Summary of Method
2.1 During an electroplating or anodizing operation, gas bubbles
generated during the process rise to the surface of the liquid and
burst. Upon bursting, tiny droplets of chromic acid become entrained in
ambient air. The addition of a wetting agent to the tank bath reduces
the surface tension of the liquid and diminishes the formation of these
droplets.
2.2 This method determines the surface tension of the bath using a
stalagmometer or a tensiometer to confirm that there is sufficient
wetting agent present.
3.0 Definitions [Reserved]
4.0 Interferences [Reserved]
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of
the user to establish appropriate safety and health practices and to
determine the applicability of regulatory limitations prior to
performing this test method.
6.0 Equipment and Supplies
6.1 Stalagmometer. Any commercially available stalagmometer or
equivalent surface tension measuring device may be used to measure the
surface tension of the plating or anodizing tank liquid.
6.2 Tensiometer. A tensiometer may be used to measure the surface
tension of the tank liquid provided the procedures specified in ASTM
Method D 1331-89, Standard Test Methods for Surface and Interfacial
Tension of Solutions of Surface Active Agents (incorporated by
reference--see Sec. 63.14) are followed.
7.0 Reagents and Standards [Reserved]
8.0 Sample Collection, Sample Recovery, Sample Preservation, Sample
Holding Times, Storage, and Transport [Reserved]
9.0 Quality Control [Reserved]
10.0 Calibration and Standardization [Reserved]
11.0 Analytical Procedure
11.1 Procedure. The surface tension of the tank bath may be
measured by using a tensiometer, a stalagmometer or any other
equivalent surface tension measuring device approved by the
Administrator for measuring surface tension in dynes per centimeter. If
the tensiometer is used, the procedures specified in ASTM Method D
1331-89 must be followed. If a stalagmometer or other device is used to
measure surface tension, the instructions provided with the measuring
device must be followed.
11.2 Frequency of Measurements.
11.2.1 Measurements of the bath surface tension are performed
using a progressive system which decreases the frequency of surface
tension measurements required when the proper surface tension is
maintained.
11.2.1.1 Initially, following the compliance date, surface tension
measurements must be conducted once every 4 hours of tank operation for
the first 40 hours of tank operation.
11.2.1.2 Once there are no exceedances during a period of 40 hours
of tank operation, measurements may be conducted once every 8 hours of
tank operation.
11.2.1.3 Once there are no exceedances during a second period of
40 consecutive hours of tank operation, measurements may be conducted
once every 40 hours of tank operation on an on-going basis, until an
exceedance occurs. The maximum time interval for measurements is once
every 40 hours of tank operation.
11.2.2 If a measurement of the surface tension of the solution is
above the 45 dynes per centimeter limit, or above an alternate surface
tension limit established during the performance test, the time
interval shall revert back to the original monitoring schedule of once
every 4 hours. A subsequent decrease in frequency would then be allowed
according to Section 11.2.1.
12.0 Data Analysis and Calculations
12.1 Log Book of Surface Tension Measurements and Fume Suppressant
Additions.
12.1.1 The surface tension of the plating or anodizing tank bath
must be measured as specified in Section 11.2.
12.1.2 The measurements must be recorded in the log book. In
addition to the record of surface tension measurements, the frequency
of fume suppressant maintenance additions and the amount of fume
suppressant added during each maintenance addition must be recorded in
the log book.
12.1.3 The log book will be readily available for inspection by
regulatory personnel.
12.2 Instructions for Apparatus Used in Measuring Surface Tension.
12.2.1 Included with the log book must be a copy of the
instructions for the apparatus used for measuring the surface tension
of the plating or anodizing bath.
12.2.2 If a tensiometer is used, a copy of ASTM Method D 1331-89
must be included with the log book.
13.0 Method Performance [Reserved]
14.0 Pollution Prevention [Reserved]
15.0 Waste Management [Reserved]
16.0 References [Reserved]
17.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]
[FR Doc. 00-19099 Filed 10-16-00; 8:45 am]
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