Determination of Ethylene Oxide at Ultra-trace Concentrations in Ambient Air Using EPA Method TO15A: Additional Laboratory Experiments

Air Monitoring, Methods, and Technology
Oral Presentation

Prepared by T. Cousett1, K. Oliver2, C. Witherspoon3, J. Machesky1
1 - US EPA Office of Research and Development, 109 TW Alexander Drive, Durham, NC, 27713, United States
2 - Retired, , , United States
3 - Amentum, , Tullahoma, TN, United States


Contact Information: [email protected]; 919-541-9767

ABSTRACT

The United States Environmental Protection Agency’s (EPA) updated Integrated Risk Information System (IRIS) risk assessment for ethylene oxide (EtO)1 resulted in an approximate 60-fold increase in the lifetime unit risk value. To assist users in the air monitoring community in measuring EtO at much lower concentrations (down to ~10 parts per trillion by volume [pptv]), the EPA Office of Research and Development (ORD) recently prepared an internal report that includes best practices for determining ultra-trace concentrations of EtO in whole air samples using specially prepared 6-L canisters and VOC preconcentration/gas chromatography–mass spectrometry (GC-MS) analytical techniques, while adhering to EPA Method TO-15A. This guidance considers EtO analytical challenges specified in the recent revision of the National Air Toxics Trends Stations (NATTS) Program Technical Assistance Document (TAD) and is informed by Method TO-15A laboratory studies conducted using newly developed analytical methods. By following the guidance and methodologies outlined in the report, we determined a Method TO-15A MDL of 12 pptv for EtO.2 Our laboratory continues to implement this guidance in further experiments, including evaluation of new canisters, intercomparison studies, and the collection and analysis of additional ambient air samples. Additional laboratory experiments demonstrating practical application of ORD’s guidance and best practices for determining ultra-trace concentrations of EtO in whole air samples using specially prepared 6-L canisters are presented here.