Trace Organic Analysis
Publications and Abstracts
A full publication list is available. Below is a selection of the publications (arranged according to publication date) where full abstracts are provided and full text of submitted papers are also included for many of the articles. These selections cover applications using low and high resolution mass spectrometry, chemical ionization, and MS/MS; separations based on HPLC, CE, and GC; sample preparation including extraction, cleanup, and concentration.
M. A. Mottaleb, W. C. Brumley, L. R. Curtis†, G. W. Sovocool*, "Nitro musk adducts of rainbow trout hemoglobin: Dose-response and toxicokinetics determination by GC-NICI-MS for a sentinel species," Am. Biotechnol. lab. 23(7), 24, 26-29 (2005).
Rainbow trout and other fish species can serve as "sentinel" species for the assessment of ecological status and the presence of certain environmental contaminants. As such they act as bioindicators of exposure. Here we present seminal data regarding dose-response and toxicokinetics of trout hemoglobin adduct formation from exposure to nitro musks which are frequently used as fragrance ingredients in formulations of personal care products. These hemoglobin adducts serve as biomarkers of exposure of the sentinel species as we have shown in previous studies of hemoglobin adducts formed in trout and environmental carp exposed to musk xylene (MX) and musk ketone (MK). Gas chromatography-electron capture negative ion chemical ionization-mass spectrometry (GC-NICI-MS) employing selected ion monitoring is used to measure 4-amino-MX (4-AMX), 2-amino-MX (2-AMX), and 2-amino-MK (2-AMK) released by alkaline hydrolysis from the sulfonamide adducts of hemoglobin. Dose-response and toxicokinetics were investigated using this sensitive method for analysis of these metabolites. In the dose-response investigation, the concentrations of 4-AMX and 2-AMX are observed to pass through a maximum at 0.10 mg/g. In the case of 2-AMK, the adduct concentration is almost the same at dosages in the range of 0.030 to 0.10 mg/g. For toxicokinetics, the concentration of the metabolites in the Hb reaches a maximum in the 3-day sample after administration of MX or MK. Further elimination of the metabolites exhibited kinetics with a presumed exponential decay and a half-life estimated to be 1-2 days. This suggests that a robust mechanism of elimination of the adducts exists in fish erythrocytes apparently analogous to that observed in mammals . Two sick fish were observed to yield from 5 to 24 times the amount of adducts of similarly exposed fish, suggesting that this elimination mechanism may have been impaired or lacking in susceptible individual fish. It appears that the adducts are destroyed in times far shorter than the expected life spans of the erythrocytes. This finding may have implications for the use of Hb biomarkers as integrative measures of exposure in some contexts. Additional conclusions from these preliminary data include the additive burden of exposure to multiple compounds and the increased susceptibility and direct observation of metabolic differences of individual members of the species completely independent of habitat and feeding habit variations.
M. A. Mottaleb*, W. C. Brumley, and G. W. Sovocool, "NITRO MUSK METABOLITES BOUND TO CARP HEMOGLOBIN: DETERMINATION BY EIMS VERSUS ELECTRON CAPTURE NEGATIVE ION MS," Int. J. Environ. Anal. Chem., 2004.
Nitroaromatic compounds including synthetic nitro musks are important raw materials and intermediates in the synthesis of explosives, dyes, and pesticides, pharmaceutical and personal care-products (PPCPs). The nitro musks such as musk xylene (MX) and musk ketone (MK) are extensively used as fragrance ingredients in PPCPs and other commercial toiletries. Identification and quantification of a bound 4-amino-MX (4-AMX) metabolite as well as a 2-amino-MK (2-AMK) metabolite were carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM) in both the electron ionization (EIMS) and electron capture (EC) negative ion chemical ionization (NICIMS) modes. Detection of 4-AMX and 2-AMK occurred after the cysteine adducts in carp hemoglobin, derived from the nitroso metabolites, were released by alkaline hydrolysis. The released metabolites were extracted into n-hexane. The extract was preconcentrated by evaporation, and analyzed by GC-SIM-MS. A comparison between the EI and EC approaches was made. EC NICIMS detected both metabolites whereas only 4-AMX was detected by EIMS. The EC NICIMS approach exhibited fewer matrix responses and provided a lower detection limit. Quantitation in both approaches was based on internal standard and a calibration plot.
M. A. Mottaleb*, W. C. Brumley, S. M. Pyle and G. W. Sovocool, "Determination of a bound musk xylene metabolite in carp hemoglobin as a biomarker of exposure by gas chromatography mass spectrometry using selected ion monitoring," J. Anal. Toxicol., 28(6), 581-586 (2004).
Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occurred after the cysteine adducts in carp hemoglobin, derived from the nitroso metabolite, were released by alkaline hydrolysis. The released AMX metabolite was extracted into n-hexane. The extract was preconcentrated by evaporation, and analyzed by GC-SIM-MS. The concentration of AMX metabolite was found to range from 6.0 to 30.6 ng/g in the carp Hb, collected from the Las Vegas Wash and Lake Mead, Nevada areas. The presence of an AMX metabolite in the carp Hb was confirmed when similar mass spectral features and the same retention time of the AMX metabolite were obtained for both standard AMX and carp Hb extract solutions. In the non-hydrolyzed and reagent blank extracts, the AMX metabolite was not detected.
T. Moy and W. C. Brumley, "MultiResidue Determination of Acidic Pesticides in Water by HPLC/DAD with Confirmation by GC/MS Using Conversion to the Methyl Ester with Trimethylsilyldiazomethane," J. Chromatogr. Sci, 47, 343-349 (2003).
A multiresidue pesticide methodology has been studied and results for acidics are reported here with base/neutral to follow. This work studies a literature procedure as a possible general approach to many pesticides and potentially other analytes that are considered to be liquid chromatographic candidates rather than gas chromatographic ones. The analysis of the sewage effluent of a major southwestern US city serves as an example of the application of the methodology to a real sample. Recovery studies were also conducted to validate the proposed extraction step. A gradient elution program was followed for the high performance liquid chromatography leading to a general approach for acidics. Confirmation of identity was by EI GC/MS after conversion of the acids to the methyl ester (or other appropriate methylation) by means of trimethylsilyldiazomethane. The 3,4-dichlorophenoxyacetic acid was used as an internal standard to monitor the reaction and PCB #19 was used for the quantitation internal standard. Although others have reported similar analyses of acids, conversion to the methyl ester was by means of diazomethane itself rather than by the more convenient and safer trimethylsilyldiazomethane. Thus, the present paper supports the use of trimethylsilyldiazomethane with all of these acids (trimethylsilyldiazomethane has been used in environmental work with some phenoxyacetic acid herbicides) and further supports the usefulness of this reagent as a potential replacement for diazomethane. The HPLC approach here could also serve as the separation basis for an LC/MS solution to confirmation of identity as well as quantitation.
W. C. Brumley and J. W. Farley, "Application of a multiwavelength laser to the capillary electrophoresis/laser-induced fluorescence determination of eosin as a groundwater migration tracer," Electrophoresis, 24, 2335-2339 (2003).
Measurements for determining of the path of groundwater migration remain an important tool in the overall assessment of environmental processes and transport of pollutants. This paper examines a multiwavelength laser for the determination of eosin, a groundwater tracer, using capillary electrophoresis/laser-induced fluorescence (CE/LIF) at excitation wavelength 514.5 nm. Eosin was one of four dyes used in a study of adjacent RCRA and Superfund sites that routinely relied on spectrofluorimetry for determination as we have previously reported. However, the improved specificity of CE/LIF is further illustrated in this work applied to the analysis of adsorbent pads placed in monitoring wells after dye injection and flushing from injection wells. The multiwavelength laser provided the capability to analyze for several dyes with one laser. The advantages/disadvantages of CE/LIF versus spectrofluorimetry are discussed. Spectrofluorimetry is fast and sensitive and will likely continue to be the primary workhorse technique. CE/LIF could provide confirmation when greater specificity is needed in a regulatory context.
S. Flaherty, S. Wark, G. Street, J. W. Farley, and W. C. Brumley, "Investigation of CE/LIF as a Tool in the Characterization of Sewage Effluent for Fluorescent Acidics: Determination of Salicylic Acid," Electrophoresis 23, 2327-2332 (2002).
The investigation of emerging contaminant issues is a proactive effort in environmental analysis. As a part of this effort, sewage effluent is of current analytical interest because of the presence of pharmaceuticals and their metabolites and personal care products. The environmental impact of these components is still under investigation but their constant perfusion into receiving waters and their potential effect on biota is of concern. This paper examines a tool for the characterization of sewage effluent using capillary electrophoresis/laser-induced fluorescence (CE/LIF) with a frequency-doubled laser operated in the ultraviolet (UV). Fluorescent acidic analytes are targeted because they present special problems for techniques such as gas chromatography/mass spectrometry (GC/MS) but are readily accessible to CE/LIF. As an example of the application of this tool, salicylic acid is determined near the 100 ng/L (7 x 10-10 M) level in sewage effluent. Salicylic acid is a metabolite of various analgesics. Relatively stable in the environment, it is a common contaminant of municipal sewage systems. Salicylic acid was recovered from freshly collected samples of the effluent by liquid-liquid extraction. Confirmation of identity was by electron ionization GC/MS after conversion of the salicylic acid to the methyl ester by means of trimethylsilyldiazomethane. CE/LIF in the UV has revealed more than 50 individual peaks in the extract and a background response that suggests a large and indeterminate number of additional compounds are present. These data together with complementary techniques provide information on the complexity and components in these effluent streams.
K. R. Rogers, A. B. Apostol, and W. C. Brumley, "Capillary Electrophoresis (CE) Immunoassay Format for Phenoxyacid Herbicides," Anal. Lett., 33, 443-453 (2000).
A capillary electrophoresis (CE) immunoassay format for 2,4-dichlorophenoxyacetic acid (2,4-D) is demonstrated. A fluorescent labeled 2,4-D analog competes with the analyte of interest for a finite number of binding sites provided by anti-2,4-D monoclonal antibodies. CE then provides a means of separating and measuring both the free and antibody-bound fluorescent tracer using laser-induced fluorescence detection. For this assay format, the amount of free tracer is a sensitive indicator for the concentration of analyte present in the sample. A sequential injection format allows the rapid analysis of a small number of samples The dynamic concentration range for 2,4-D in either buffer or river water is 5 ppb to 1000 ppb.
D. B. Patterson, W. C. Brumley, V. Kelliher, and P. L. Ferguson, "Determination of Clofibric Acid in Sewage Effluent by GC/MS: Conversion to the Methyl Ester with Trimethylsilyldiazomethane," Amer. Lab. 34, 20-28 (2000).
Clofibric acid is a metabolite of various lipid regulators. Relatively long-lived in the environment, it is a common contaminant of municipal sewage systems in Europe. Here we present an analysis of clofibric acid in the sewage effluent of a major southwestern US City. Clofibric acid was recovered from freshly collected samples of the effluent by liquid-liquid extraction as part of a broad characterization effort. Recoveries from solid phase extraction using styrene/divinylbenzene adsorbent were also studied. Analysis was by EI GC/MS after conversion of the clofibric acid to the methyl ester by means of trimethylsilyldiazomethane. 3,4-Dichlorophenoxyacetic acid was used as an internal standard with additional use of highly orthosubstituted polychlorinated biphenyl congeners as alternative internal standards. Although others have reported similar analyses of clofibric acid, conversion to the methyl ester was by means of diazomethane itself rather than the more convenient and safer trimethylsilyldiazomethane. Thus, the present paper appears to be the first report of the use of trimethylsilyldiazomethane with clofibric acid (trimethylsilyldiazomethane has been used in environmental work with phenoxyacetic acid herbicides, which are structurally similar to clofibric acid) and further supports the usefulness of this reagent as a potential replacement for diazomethane. The clofibric acid level in the original effluent was determined to be 234 ng/L.
W. C. Brumley, A. H. Grange, V. Kelliher, D. B. Patterson, A. Montcalm, J. Glassman, and J. W. Farley, "Environmental Screening of Acidic Compounds Based on Capillary Zone Electrophoresis/Laser-Induced Fluorescence Detection with Identification by Gas Chromatography/Mass Spectrometry and Gas Chromatography/High-Resolution Mass Spectrometry," JAOAC International, 83, 1059-1067 (2000).
This work presents the application of capillary zone electrophoresis/laser-induced fluorescence (CZE/LIF) to the discovery of acidic compounds in environmental matrices or the screening of extracts for acidic components. Based on published studies, coal-derived materials should contain a significant fraction of acidic compounds relative to materials derived from petroleum and shales. Such compounds may be useful as marker compounds for site assessment and source apportionment issues, and their identification may be important in toxicological and other health issues. We have used deep UV light from the frequency doubled AR ion laser at 244 NM and 257 NM to study extracts of samples. The CZE/LIF technique possesses good sensitivity and therefore overcomes one of the limitations of CZE with UV detection. The present example depends on high pressure/temperature solvent extraction of polynuclear aromatic hydrocarbon-contaminated soil followed by separation using CZE. The anionic analytes were separated using borate or phosphate buffer (pH 9.2 to 12.3) after a chemical class separation. Samples were also characterized by GC/MS using full scans at low resolution, and elemental compositions were determined unequivocally with GC/high resolution MS (GC/HRMS) using mass peak profiling. The similarity of low resolution EI mass spectra for a standard, 1-hydroxypyrene, and for a series of compounds in a contaminated-soil extract suggested that several types of phenolic and hydroxy-PNAs were present including hydroxylated derivatives of fluorenes, fluoranthenes, and pyrenes. GC/HRMS using mass peak profiling confirmed the elemental compositions of the hydroxyfluorenes and hydroxypyrenes (and presumably hydroxyfluoranthenes) as [C13H10O] and [C16H10O], respectively. A new version of the mass peak profile software was written for the Finnigan-MAT 900S-Trap similar to that developed previously for the VG 250SE. Inclusion of a calibration ion in addition to a lock mass ion in the MID descriptor provided errors of less than 1 ppm for the three partial profiles of the analytes. A mass resolution of 31,000 was used to resolve the analyte signals from interferences evident in the full M+1 and M+2 profiles in the case of the hydroxyfluorenes. Derivatization was also carried out to form the tert-butyldimethylsilyl derivatives of phenolic hydroxy groups as a further confirmation of structure.
G. Wayne Sovocool, W. C. Brumley, J. R. Donnelly, "Capillary Electrophoresis and Capillary Electrochromatography of Organic Pollutants," Electrophoresis, 20, 3297-3310 (1999).
W. C. Brumley and C. Gerlach, "Capillary Electrophoresis/Laser-induced Fluorescence in Groundwater Migration Determination," Am. Lab., 31, 45-49 (1999).
The results presented in this article show that capillary electrophoresis with laser-induced fluorescence detection can be a valuable method for detecting the fluorescent dyes that are commonly used as tracers in groundwater migration studies.
T. W. Moy, P. L. Ferguson, A. H. Grange, W. H. Matchett, V. A. Kelliher, W. C. Brumley, J. Glassman, and J. W. Farley, "Development of Separation Systems for Polynuclear Aromatic Hydrocarbon Environmental Contaminants Using Micellar Electrokinetic Chromatography with Molecular Micelles and Free Zone Electrophoresis," Electrophoresis, 19, 2090-2094 (1998).
Of four systems available from the literature, based on cyclodextrins, dioctylsulfosuccinate, bile salts, and molecular micelles consisting of oligomers of undecylenic acid, the most successful separation system in our hands is based on the molecular micelles, oligomers of sodium undecylenic acid (OSUA). We have employed organic additives of acetonitrile, acetone, and tetrahydrofuran in achieving separations of polyaromatic hydrocarbons (PNAs) using molecular micelles. Generally, successful separations are achieved with 20-40% composition as the organic additive in an 8 mM borate buffer. We separated 16 PNAs with 20% tetrahydrofuran in a system of 8 mM borate and 0.125 g/10 mL (ca. 6.25 mM) of OSUA. Typical extracts of environmental samples contain additional analytes besides the typical 16 target compounds. Among these are the nitrogen-containing aromatics that can act as cations under conditions of low pH and additional compounds that can act as anions under basic conditions in free-zone electrophoresis. These additional classes of analytes are separated by capillary zone electrophoresis/laser-induced fluorescence detection using a frequency-doubled laser operated at 257 nm.
N. R. Herron, J. R. Donnelly, G. R. Nichol, and W. C. Brumley, "Microwave Heating to Facilitate Supercritical Fluid Extractions," Amer. Environ. Lab., 10, pp. 1, 5 (1998).
W. C. Brumley, E. Latorre, V. Kelliher, A. Marcus, and D. Knowles, "Determination of Chlordane in Soil by LC/GC/ECD and GC/EC NIMS with Comparison of ASE, SFE, and Soxhlet Extraction," J. Liq. Chromatogr., 21, 1199-1216 (1998).
Chlordane is a polychlorinated mixture that was used as a long-lived pesticide and now is considered a potential endocrine-disrupting compound. The Environmental Sciences Division is involved in modernizing methods for a number of analytes that are potential target substances for dietary studies, endocrine disrupter studies, Superfund site monitoring, and human exposure studies. In this work, chlordane is determined in soils using each of three different liquid phase/supercritical fluid (CO2) extractions followed by a two-dimensional chromatographic separation based on high performance gel permeation chromatography (HPGPC) followed by GC/electron capture detection (GC/ECD) and GC/electron capture negative ion mass spectrometry (GC/EC NIMS). Liquid phase extractions were carried out using accelerated solvent extraction, supercritical fluid extraction, and Soxhlet extraction. The preparative liquid chromatographic part of the work is used in an off-line fractionation mode of HPGPC. Further cleanup is afforded by solid-phase extraction using silica cartridges. Soils spiked at 2 ppm, 0.2 ppm, and 0.02 ppm were quantitated using GC/ECD and GC/EC NIMS with recoveries usually greater than 80%. Soil from a Superfund site and a standard reference material sediment were analyzed as examples of real samples. The modernized methodology developed in this work should offer improved approaches for Superfund analyses and for monitoring methods used in determining potential exposure to endocrine-disrupting compounds while minimizing solvent usage compared to previous methodology.
W. H. Matchett, W. Winnik, and W. C. Brumley, "A Kinetic Study of the Methanolysis of the Sulfonylureas Bensulfuron and Sulfometuron Using Capillary Electrophoresis," Electrophoresis, 18, 205-213 (1997).
W. H. Matchett and W. C. Brumley, "Preconcentration of Aliphatic Amines from Water Determined by Capillary Electrophoresis with Indirect UV Detection," J. Liq. Chromatogr., 20, 79-100 (1997).
W. H. Matchett and W. C. Brumley, "Determination of Aliphatic Amines in Aqueous Matrices Using Capillary Electrophoresis with Indirect UV Detection," J. Liq. Chromatogr., 1997.
Electrophoretic properties and preconcentration methodology are explored for the determination of aliphatic amines (C1 to C4 substituted primary, secondary, and tertiary) and alkanolamines in water by free zone capillary electrophoresis (CZE) with indirect UV detection. The extraction of amines from water (pH 5) as a preconcentration step is studied using ion exchange solid-phase extraction (SCX) cartridges, cation ion exchange extraction disks, and ion-pairing with C18 extraction disks. The resulting quantitation limits are in the 15-ppb range. Mobilities of amines are correlated with their Stokes' radii. Increased selectivity for resolving closely related amines under CZE is explored using nonionic surfactants, pH adjustment, and optimized background electrolyte. Techniques are developed for obtaining stable baselines in the indirect detection mode. Linearity, sensitivity, and efficiency are explored for this mode of detection.
A. H. Grange and W. C. Brumley, "A Mass Peak Profile Generation Model to Facilitate Determination of Elemental Compositions of Ions Based on Exact Masses and Isotopic Abundances," J. Am. Soc. Mass Spectrom., 8, 170-182 (1997).
C. M. Pace, J. R. Donnelly, J. L. Jeter, W. C. Brumley, and G. W. Sovocool, "Determination of Aromatic Amines in Soils," J. AOAC Internat., 79, 777-783 (1996).
A rapid liquid chromatographic (LC) method with ultraviolet (UV) or fluorescence detection was developed for parts-per-billion levels of aromatic amines in soils. 2,4-Diaminotoluene, pyridine, aniline, 2-picoline, 2-toluidine, 5-nitro-2-toluidine, 2-methyl-6-ethylaniline, 4-aminobiphenyl, 4-nitroaniline, 1-naphthylamine, 2-methoxyaniline, and 2-naphthylamine were tested. The method involves extraction by sonication with 1% ammonium hydroxide-acetonitrile and analysis by LC using gradient elution with aqueous 0.01 M ammonium acetate-0.0005% triethylamine and acetonitrile. Recoveries of 67-106% (9.2 and 34% for 1-and 2-naphthylamines, respectively) were obtained from sand and organic-containing soils spiked in the parts-per-million range. Recoveries from sand spiked at 8.5-25 ppb were 88-105%. Recoveries from organic soil varied from nondetectable to 86% at spikes of 85-500 ppb. Detection limits ranged from 0.5 ppb for highly fluorescent 2-naphthylamine (by fluorescence detection) to 0.5 ppm for nonfluorescing pyridines (by UV detection).
W. H. Matchett, W. Winnik, and W. C. Brumley, "Capillary Electrophoretic Behavior of Seven Sulfonylurea Herbicides," J. Cap. Electrophoresis, 3, 199-204 (1996).
A. H. Grange and W. C. Brumley, "Mass Peak Profiling from Selected Ion Recording Data Acquired at High Mass Resolution: An Important New Analytical Technique for Mass Spectral Determinations," Environ. Testing and Analysis, March/April, 22-26, 1996.
A. H. Grange and W. C. Brumley, "Identification of Components in a Complex Mixture by Determination of Exact Masses and Relative Abundances using Mass Peak Profiling," LC GC, 14, 978-986 (1996).
A. H. Grange and W. C. Brumley, "Determining Elemental Compositions from Exact Masses and Relative Abundances of Ions," Trends Anal. Chem., 15, 12-17 (1996).
J. R. Donnelly, A. H. Grange, N. R. Herron, G. R. Nickhol, J. L. Jeter, R. J. White, and W. C. Brumley, and J. Van Emon, "Modular Methodology for Determination of Polychlorinated Biphenyls in Soil as Aroclors and Individual Congeners," J. AOAC Internat., 79, 953-961(1996).
W. C. Brumley, P. L. Ferguson, A. H. Grange, J. L. Donnelly, and J. W. Farley, "Applications of Capillary Electrophoresis/Laser-Induced Fluorescence Detection to Groundwater Migration Studies," J. Cap. Electrophoresis, 3, 295-299 (1996).
Capillary electrophoresis (CE) has been applied to the determination of groundwater migration based on laser-induced fluorescence (LIF) detection and traditional spectrofluorimetry. Detection limits of injected dye/fluorescent whitening agent (tinopal) in the low ppt ranges have been accomplished with both CE/LIF based on the HeCd laser and with a spectrofluorometer. This approach was used for a real world problem in determining groundwater migration between adjacent RCRA and Superfund sites. Fluorescent dyes were injected into wells and were discovered in monitoring wells by using extracting pads that adsorbed the dye. The approaches based on CE/LIF exhibits increased specificity over existing approaches due to the separation and unique migration time of the dye. Additional studies were aimed at achieving sub-ppt levels in the water using solid-phase extraction and field-amplified injection techniques.
W. Winnik, L. D. Betowski, and W. C. Brumley, "Negative Ion Mass Spectrometry of Sulfonylurea Herbicides," J. Mass Spectrom., 30, 1574-1580 (1995).
M. Jung and W. C. Brumley, "Trace Analysis of Fluorescein-Derivatized Phenoxy Acid Herbicides by Micellar Electrokinetic Chromatography with Laser-induced Fluorescence Detection," J. Chromatogr. A, 717, 299-308 (1995).
Micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence (LIF) detection was used for the trace analysis of phenoxy acid herbicides. Capillary electrophoresis (CE) with LIF detection, which has not previously been used for pesticide analysis, overcomes the poor sensitivity of on-column UV detection. A novel derivatization procedure was developed which is suitable for nanogram amounts of organic acids. In the procedure, the acids are activated by hydroxybenzotriazol (HOBT) and diisopropylcarbodiimide (DIC) and reacted with 5-(aminoacetamido)fluorescein in dimethylformamide at ambient temperature. The fluorescent derivatives of all relevant phenoxy acid herbicides were separated in a single run by MEKC. A 488 nm Ar laser line was used for excitation. The reproducibility and reliability of the method were evaluated. The detection limit was 2 fg for a 4-nL injection, but for practical reasons, a minimum of 1 ng per compound should be subjected to the derivatization. The applicability of the described method to the extract of an aqueous sample was demonstrated.
An assessment of the handling of environmental samples for capillary electrophoresis (CE) is presented for both aqueous and solid matrices. Sample handling for environmental analysis is of ongoing research interest to the analytical chemistry research program at the EPA's National Exposure Research Laboratory (Las Vegas). For aqueous matrices, both on-column and off-column techniques for preconcentration/cleanup are described. On-column techniques include field-amplification and isotachophoresis. Factors of concentration up to 1,000 have been reported. Cleanup techniques are also discussed. For samples from solid matrices, especially soil, both extraction/cleanup and final separation/determination are illustrated. Emphasis is placed on comparing extraction procedures with respect to speed, analyte recovery, solvent usage, and ease of interfacing with CE. Cleanup procedures and detection approaches are discussed. Prospects for future developments are offered, and suggestions for future research are made.
W. C. Brumley, "Micellar Electrokinetic Chromatography: A New Tool for Field-Screening of Semivolatiles," Proceedings of the Fourth International Symposium on Field Screening Methods for Hazardous Waste and Toxic Chemicals, February 22-24, 1995, Las Vegas, NV (sponsored by Air & Waste Management Association).
W. C. Brumley, "Environmental Applications of Capillary Electrophoresis for Organic Pollutant Determination," LC·GC, 13, 556-568 (1995).
Capillary electrophoresis (CE) is rapidly gaining the interest of analytical chemists as a separation technique of unique and powerful capabilities. The biochemical and pharmaceutical fields have used CE to solve important problems such as protein separations, drug (including strong organic bases) separations, chiral separations, and DNA sequencing. In contrast, CE has captured little interest in the arena of environmental analysis. The author presents a review of the applications of CE to environmental problems, concentrating on organic pollutants. A rationale is presented for the importance of CE in the solution of environmental analytical problems. Several areas of application of CE are still relatively undeveloped, so that many fruitful avenues of investigation are open to interested investigators.
A. H. Grange, J. R. Donnelly, W. C. Brumley, S. A. Billets, and G. W. Sovocool, "Mass Measurements by an Accurate and Sensitive Selected-Ion-Recording Technique," Anal. Chem., 66,4416-4421 (1994).
W. C. Brumley and W. J. Jones, "Comparison of Micellar Electrokinetic Chromatography with Capillary Gas Chromatography in the separation of phenols, anilines, and polynuclear aromatics: Potential Field-Screening Applications of MEKC," J. Chromatogr., 680, 163-173 (1994).
W. C. Brumley, C. M. Brownrigg, and A. H. Grange, "Capillary Liquid Chromatography/Mass Spectrometry and Micellar Electrokinetic Chromatography as Complementary Techniques in Environmental Analysis," J. Chromatogr., 680, 635-642 (1994).
W. C. Brumley and C. M. Brownrigg, "Applications of Micellar Electrokinetic Chromatography in the Determination of Benzidines Following Extraction from Water, Soil, Sediment, and Chromatographic Adsorbents," J. Chromatogr. Sci., 32, 69-75 (1994).
Micellar electrokinetic chromatography (MEKC) with ultraviolet detection is used to determine benzidine (4,4'-diaminobiphenyl) and three substituted analogs (3,3'-dimethoxybenzidine, 3,3'-dimethylbenzidine, and 3,3'-dichlorobenzidine) in water, soil, and sediment. Recovery of benzidines from chromatographic adsorbents is also determined by MEKC. The use of short capillaries makes possible the determination of benzidines in soil extracts in about 2 minutes after solid-phase extraction cleanup with C18 cartridges. Although benzidines are determined down to 10 ng/g in water, problems are encountered in the extraction of benzidines from soil and sediment matrices and from chromatographic adsorbents. Several solvent systems are investigated with moderate success for extraction of benzidines at contaminant levels in the µg/g range for soil. MEKC of additional aromatic amines is carried out, allowing assessment of the specificity of the determination.
W. C. Brumley, C. M. Brownrigg, and A. H. Grange, "Determination of Toxaphene in Soil by Electron-capture Negative Ion Mass Spectrometry after Fractionation by High-performance Gel Permeation Chromatography," J. Chromatogr., 633, 177-183 (1993).
Toxaphene is extracted from soil by standard procedures using Soxhlet or sonication methods. The extract is fractionated by high-performance gel permeation chromatography (HPGPC), which separates toxaphene from the bulk of co-extractives including polychlorinated biphenyls. This HPGPC fractionation has broad application to many problems of environmental analysis. A solid-phase extraction cleanup with silica gel further removes any polar components present in the collected fraction. Determination of toxaphene is accomplished by electron-capture negative ion mass spectrometry (ECNI-MS) after introduction by capillary gas chromatography. Levels down to 100 µg/kg in soil are obtainable. Brief mention is made of high-resolution ECNI-MS carried out at a resolution of 10,000.
W. C. Brumley and C. M. Brownrigg, "Electrophoretic Behavior of Aromatic-Containing Organic Acids and the Determination of Selected Compounds in Water and Soil by Capillary Electrophoresis," J. Chromatogr., 646, 377-389 (1993).
The behavior of 56 aromatic-containing organic acids (ACOAs) was obtained under free zone electrophoresis and under micellar electrokinetic chromatography using cholic acid as the micellar agent. The compound classes encompass phenoxy acid herbicides, phenylalkanoic acids, aromatic carboxylic acids, aromatic sulfonic acids, azo and other dyes, and ACOAs containing nitrogen. Seven compounds were studied with respect to extraction and cleanup from spiked water and soil at levels of 1.0 and 0.1 µg/g and 100 and 20 µg/g, respectively. A general scheme of isolation and cleanup was developed that used extraction disks and solid-phase extraction cartridges. Average recoveries for three determinations ranged from 26.5 to 98.2% with relative standard deviations ranging from 6.7 to 55%.
W. C. Brumley, C. M. Brownrigg, and G. M. Brilis, "Characterization of Nitrogen-Containing Aromatic Compounds in Soil and Sediment by GC/MS After Fractionation," J. Chromatogr., 558, 223-233 (1991).
Nitrogen-containing aromatic compounds (NCACs) are characterized in soil and sediment by full-scan capillary gas chromatography-mass spectrometry under electron ionization. The approach makes use of fractionation of methylene chloride extracts based first on partitioning of the basic compounds into acid. The neutral NCACs are then isolated by preparative thin-layer chromatography which serves to separate them from the bulk of the polynuclear aromatic hydrocarbons. NCACs can then be determined to 100 µg/kg or below using deuterated internal standards. Examples of determinations in sediment and creosote-contaminated soil are given. An advantage of the two-step fractionation scheme is the chemical separation of azaarenes and cyanoazaarenes of the same elemental composition which facilitates identification of compound class and simplifies chromatographic separations.
W. C. Brumley and J. A. Sphon, "Regulatory Mass Spectrometry," Biomed. Mass Spectrom., 8, 390-396 (1981).
The history of regulatory mass spectrometry at the Food and Drug Administration began In the early 1960s and was initiated by J. N. Damico using a time-of-flight instrument with limited mass range, resolution and sensitivity. Early work involved confirmation of identity of compounds using direct probe introduction and lull mass scans. From 1964 to 1969 an important application of mass spectrometry was the analysis of pesticides and elucidation of their fragmentation pathways. Regulatory mass spectrometry was used to confirm manually trapped gas chromatographic peaks and it solved the problem of false positive identifications based solely on gas chomatographic retention time. In time the mass spectrometer became viewed as the ultimate gas chromatographic detector. Another important early regulatory case involved the question of Krebiozen as a cancer cure. Krebiozen was analyzed by mass spectrometry and found to consist of creatinine, which was known to have no activity as an anti-cancer drug. Such basic information as the identity of a substance demonstrated the indispensable regulatory use of mass spectrometry. The basic problem of identification has broadened in scope to include multicomponent analyses, trace level detection, quantitation, and newer ionization techniques. Two examples illustrate the continuing development of regulatory mass spectrometry. Negative ion chemical ionization mass spectrometry in the analysis of aflatoxin BI involves use of a newer ionization technique. The requirements of trace level detection and specificity are further stretched in the gas chromatographic mass spectrometric selected ion monitoring detection, confirmation and quantitation of tetrachlorodibenzo-p-dioxins.
William C. Brumley, Elizabeth M. Shafter, and Paul E. Tillander "Determination of Phthalates in Water and Soil by Tandem Mass Spectrometry Under Chemical Ionization Conditions with Isobutane as Reagent Gas," Intern. J. Off. Anal. Chem. 77, 1230-1236 (1970)
Eleven phthalate esters spiked in water and soil were determined by tandem mass spectrometry (MS) under positive chemical ionization mass spectrometry (CIMS) conditions with isobutane as reagent gas. Emphasis was placed on the determination step because tandem MS and CIMS are not widely adopted in current methods of the U.S. Environmental Protection Agency. Extraction by sonication and cleanup by use of a solid-phase extraction cartridge were adopted. The relative response factors gave relative standard deviations (RSDs) of 12-30% when 2 unlabeled internal standards were used. The relative abundances of monitored ions gave relative abundance deviations of less than 8%. The method confirms identity, including molecular weight, and quantitates with high specificity. Results obtained with 2 unlabeled internal standards were compared with results obtained with a stable-isotope-labeled internal standard for dloctyl phthalate.
L. Riddick, E..L. Gentry, Mark. McDaniel, and W. C. Brumley, "Evaluation of N-methyl-n-tert-butyldimethylsilyltrifluoroacetamide for Environmental Analysis under Both EIMS and Electron Capture Nicims Conditions and Comparison to Trimethylsilyl Reagents under EIMS", Internat. J. of Environ. Anal. Chem., 86, 299-312 (2006).
N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide (MTBSTFA) is a silylating agent with a range of applicability in clinical and environmental analysis, particularly when substrates possess at least moderate acidity. In this paper we demonstrate its applicability and limitations as a reagent for environmental analysis by comparing and contrasting two different target analyte problems in a sewage effluent matrix. In one case electron ionization was used for the determination of three potential endocrine disrupting compounds: 17ß-estradiol, ethynyl estradiol, and estrone where the phenolic functionality was silylated with MTBSTFA and compared with results using N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA) as the reagent. In this instance, a large volume of effluent was subjected to either solid phase extraction followed by cleanup using high performance gel permeation chromatography (AppI) or liquid/liquid extraction followed by SPE fractionation and HPLC fractionation (AppII). The method using BSTFA rather than MTBSTFA was demonstrated to work down to low and sub ppt levels where the target compounds were found. In a parallel and contrasting study, sewage effluent was analyzed for 3,5,6-trichloropyridinol (TCP) by extracting one liter of water using liquid-liquid extraction and determined by GC/MS operated in the negative ion chemical ionization (electron capture) mode after derivatization with MTBSTFA. TCP is the major metabolite of the commonly used insecticide, chlorpyrifos, and herbicide trichlorpyr . The recoveries using dichloromethane as the extractant were 59 % with a relative standard deviation of 2%. This method was used to investigate levels of TCP in sewage effluent. During this analysis a tentatively identified additional isomer of TCP (X-TCP) was found. The 3,5,6-TCP, the common chlorpyrifos metabolite and the synthesized isomer, 3,4,5-TCP were compared with X-TCP. All three isomers have significantly different retention times. The average level of 3,5,6-TCP was 3.4 ng/L while the level of X-TCP was 39.8 ng/L. The two approaches are compared and contrasted with respect to artifact formation and matrix component effects. The reagent MTBSTFA is found to be suitable for quantitative analysis of environmental samples for relatively acidic substrates (e.g., phenols and carboxylic acids). More powerful silylating agents such as N-Methyl-N-trimethylacetamide or BSTFA are required for sterols and similar substrates. The stability of the two silylating reagents appears to be similar and practical for accurate quantitative analysis. Differences in EI spectra with respect to fragmentation may also dictate which reagent is preferred.
L. Riddick and W. C. Brumley, "Capillary Electrophoresis with Laser-induced Fluorescence: Environmental Applications," in CE from Small Ions to Macromolecules, P. Schmitt-Kopplin, ed., Methods in Molecular Biology Series; Humana Press: Totowa, New Jersey, in press, 2006.
Capillary electrophoresis (CE), especially free zone CE, offers a relatively simple separation with moderate selectivity based on the mobility of ions in solution. Laser-induced fluorescence (LIF) detection, an extremely sensitive technique, can be coupled with a variety of separation conditions to achieve sensitive and quantitative results. When these techniques are combined, CE/LIF provides the sensitivity and increased selectivity that makes trace level environmental analysis of fluorescent compounds possible at or below levels typical for GC/MS. We offer a panoramic review of the role of these tools in solving environmental and related analytical problems before providing a detailed experimental protocol.
M. A. Mottaleb, and W. C. Brumley, "Environmental Analytical Chemistry of Pharmaceutical and Personal Care Products: The Separations Focus Turns to Polar Analytes," Trends in Chromatography, 2, 11-29 (2006).
Within the scope of a number of emerging contaminant issues in environmental analysis, one area that has received a great deal of public interest has been the assessment of the role of pharmaceuticals and personal care products (PPCPs) as stressors and agents of change in ecosystems as well as their role in unplanned human exposure. The relationship between personal actions and the occurrence of PPCPs in the environment is clear-cut and comprehensible to the public. In this overview, we attempt to examine the separations aspect of the analytical approach to the vast array of potential analytes among this class of compounds. We also highlight the relationship between these compounds and endocrine disrupting compounds (EDCs) and between PPCPs and EDCs and the more traditional environmental analytes such as the persistent organic pollutants (POPs). Although the spectrum of chemical behavior extends from hydrophobic to hydrophilic, the current focus has shifted to moderately and highly polar analytes. Thus, emphasis on HPLC and LC/MS has grown and MS/MS has become a detection technique of choice with either electrospray ionization or atmospheric pressure chemical ionization. This contrasts markedly with the bench mark approach of capillary GC, GC/MS and electron ionization in traditional environmental analysis. The expansion of the analyte list has fostered new vigor in the development of environmental analytical chemistry, modernized the range of tools applied, and has revealed the need for awareness of the parallel developments in pharmaceutical analysis and biomedical analysis. We place particular emphasis on the separations that undergird successful analysis of PPCPs and the final separation/detection that provides the primary data upon which risk assessments and other determinations will ultimately be based. We suggest that the new emphasis on PPCPs has now defined a turning point in environmental analysis and set the stage for a significant new challenge that we briefly explore in this appraisal of the field.