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SUPPLEMENT TO EPA COMPENDIUM METHOD TO-15 - REDUCTION OF METHOD DETECTION LIMITS TO MEET VAPOR INTRUSION MONITORING NEEDS
Citation:
Daughtrey Jr., E. H., K. D. Oliver, H. H. Jacumin Jr., AND W A. McClenny. SUPPLEMENT TO EPA COMPENDIUM METHOD TO-15 - REDUCTION OF METHOD DETECTION LIMITS TO MEET VAPOR INTRUSION MONITORING NEEDS. Presented at Symposium on Air Quality Measurement Methods and Technology, Research Triangle Park, NC, April 20-22, 2004.
Impact/Purpose:
Develop innovative and customized new measurement approaches for air toxic VOCs as requested by methods development clients.
Description:
The Supplement to EPA Compendium Method TO-15 provides guidance for reducing the method detection limit (MDL) for the compound 1,1-dichloroethene (1,1-DCE) and for other volatile organic compounds (VOCs) from 0.5 parts per billion by volume (ppbv), as cited in Method TO-15, to much lower concentrations. Revisions were made to the wording of Method TO-15 where the original language proved limiting to the goal of extending Method TO-15 to low parts per trillion by volume (pptv) levels or where minor omissions were observed. Also, recommendations in the form of additions were made on aspects of laboratory procedure deemed critical to low-pptv-level analysis. Specifically, the MDL for 1,1-DCE was determined to be 6 pptv. During this effort, a capability for preparing 1,1-DCE sample concentrations of 30 pptv and 60 pptv in ambient air was developed. Using this capability and the capability to prepare samples of humidified zero air, samples were prepared in canisters and sent to three contract laboratories as unknowns. Subsequent comparison of results indicated close agreement among the laboratories while maintaining the performance standards for replicate precision (25%) and audit accuracy (30%) originally specified in Method TO-15. The following compounds were also detected at low pptv levels in canisters filled with spiked ambient air: chloroethene, dichloromethane, cis-1,2-dichloroethene, trichloromethane, 1,2-dichloroethane, benzene, 1,1,1-trichloroethane, trichloroethene, and tetrachloroethene. Since the different laboratories employed different analytical procedures, the use of a performance-based method appears justified.
This work has been partially funded by the United States Environmental Protection Agency under Contract 68-D-00-206 to ManTech Environmental Technology, Inc. This paper has been reviewed in accordance with the Agency's peer and administrative review policies and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.