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Method TO-15A: Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially
Citation:
Whitaker, D., K. Oliver, D. Turner, I. MacGregor, AND D. Shelow. Method TO-15A: Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially. U.S. EPA Office of Research and Development, Washington, DC, 2019.
Impact/Purpose:
The 1990 Clean Air Act Amendment Title III included a list of 189 toxic air pollutants for which emissions were to be reduced. Methods developed in the 1990s to monitor many of these compounds are currently still being used for measuring air toxics in ambient air (e.g. volatile organic chemicals, aldehydes and ketones, PAHs, metals) and are commonly referred to as the TO Methods (Toxic Organic Methods). The 1999 compendium of TO methods included EPA Method TO-15 which provided details for a canister method that was to be used for measuring VOCs in ambient air. This method was developed at a time when the ambient concentrations of many VOCs were higher than current concentrations. With the general VOC concentrations decreasing since the 1990s and expected continued decreases; a more sensitive method is needed in order to provide useful data into the future. There has not been a systematic evaluation of the method nor an attempt to update the method procedures and publish a revised TO-15 until now. EPA Method TO-15A compiles in a single document the best practices and lessons learned by users of the method over the past 20 years. It has been totally rewritten to address and incorporate improvements in canister, sampling, preconcentration, and analytical instrumentation technologies. It is written as a performance-based procedure whereby equipment, instruments, operations, best practices, and acceptance and performance criteria are described. It provides extensive detail on all processes involved in air sampling and analysis using current canister and GC/MS technologies. Significant changes include the reduction in the minimum concentration for which the method is applicable from 500 pptv to 20 pptv and the reduction of canister cleanliness requirements from 200 pptv to 20 pptv. This is in acknowledgment of general reductions in ambient air VOC concentrations to date and expected continued reductions of VOCs in the United States of America as well as improvements in canister technology, canister hygiene practices, and analytical instrument sensitivity. It is anticipated that the adaptation of TO-Method 15A will improve the quality of the data reported to the US EPA and provide more uniform results. TO-15A will also provide users access to a single document providing thorough treatment of the fundamentals and details of canister sampling and analysis. It is expected that this method will be of interest to and used by the Regions, States, Tribes, and other VOC analytical laboratories in the measurement of VOCs in ambient air. Planned publication of this document is on EPA's Ambient Monitoring Technology Information Center (AMTIC) website.
Description:
EPA Method TO-15A compiles in a single document the best practices and lessons learned by users of the method over the past 20 years. It has been totally rewritten to address and incorporate improvements in canister, sampling, preconcentration, and analytical instrumentation technologies. It is written as a performance-based procedure whereby equipment, instruments, operations, best practices, and acceptance and performance criteria are described. Method TO-15A provides extensive detail on all processes involved in air sampling and analysis using current canister and GC/MS technologies. Significant changes include the reduction in the minimum concentration for which the method is applicable from 500 pptv to 20 pptv and the reduction of canister cleanliness requirements from 200 pptv to 20 pptv. This is in acknowledgment of general reductions in ambient air VOC concentrations to date and expected continued reductions of VOCs in the United States of America as well as improvements in canister technology, canister hygiene practices, and analytical instrument sensitivity. It is anticipated that the adaptation of TO-Method 15A will improve the quality of the data reported to the US EPA and provide more uniform results. TO-15A will also provide users access to a single document providing thorough treatment of the fundamentals and details of canister sampling and analysis.