|Text of Test Method 23 - Dioxins and Furans
|Electronic Reporting Tool
FREQUENTLY ASKED QUESTIONS (FAQS) for Method 23
- Is there a maximum temperature limit for this method?
Method 23 requires me to rinse the glassware in the sampling
train with acetone and methylene chloride and then perform a separate
"quality assurance" rinse with toluene. The method requires that I keep
the toluene rinse separate and analyze it separately. Can't I save some
money by combining these rinses and analyzing them together?
The method is clear that the toluene rinse should be stored separately
and analyzed separately. However, based on the information that we have
collected using this procedure since Method 23 became final, we now know
that the toluene rinse will not significantly increase the amount of
recovered dioxins/furans. Therefore, it is appropriate to allow a
laboratory to combine the toluene rinse with the methylene chloride/
acetone rinse so that they can save the analytical cost of an additional
sample fraction. However, the combining of the toluene rinse with the
methylene chloride/acetone rinse for analysis must be handled as a minor
change to a test method. That means that the tester/source must make it
clear in their test plan that they are making this change and that the
responsible agency (typically the state, but sometimes the EPA Region)
must approve the change before the tester/source proceeds.
For Method 23, do I need to correct the emissions results to 12 percent CO2?
We sometimes require that industries correct their emission data to a
fixed CO2 or O2 concentration to prevent the industry from simply
diluting their emission gases with ambient air to reduce the
concentration of the measured pollutant. The CO2 or O2 concentration
that they must use to correct their measured emissions is somewhat
arbitrary, but requiring that everyone correct their results means that
everyone will report their emissions on the same basis. Because the
concentration used to correct the emission data may vary among different
industries, the required correction is part of the emission limit rather
than the test method.
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