Improving Confidence in the TO-15 Atmospheric Analysis at Trace Concentrations
Oral Presentation
Prepared by W. Whipple
US EPA Region 5 Chicago Regional Laboratory, 536 S Clark Street, 10th Floor, Chicago, IL, 60626, United States
Contact Information: whipple.wayne@epa.gov; 312-353-9063
ABSTRACT
Select Volatile Organic Compounds (VOCs) in the atmosphere and soil gas have been measured using the EPA Compendium method TO-15 by gas chromatography and mass spectrometry (GC/MS) for decades while the needed detection levels have lowered beyond the achievable limits of detection with the available instrumentation and methodology. Risk assessment projects have suggested limits for select compounds to below 10 pptv for a 1/1 x 106 cancer risk ratio. Other data quality objectives place the measured results into models with the non detected compounds being entered in as 1/2 the limit of detection which can provide a very significant error into the model.
Special care must be taken in the atmospheric analysis that includes different calibration models, detailed cleaning and certification procedures and enhanced quality assurance practices. This presentation discusses some suggestions to improve the TO-15 based guidance document to improve confidence in the results at these extremely low detection limits.
Oral Presentation
Prepared by W. Whipple
US EPA Region 5 Chicago Regional Laboratory, 536 S Clark Street, 10th Floor, Chicago, IL, 60626, United States
Contact Information: whipple.wayne@epa.gov; 312-353-9063
ABSTRACT
Select Volatile Organic Compounds (VOCs) in the atmosphere and soil gas have been measured using the EPA Compendium method TO-15 by gas chromatography and mass spectrometry (GC/MS) for decades while the needed detection levels have lowered beyond the achievable limits of detection with the available instrumentation and methodology. Risk assessment projects have suggested limits for select compounds to below 10 pptv for a 1/1 x 106 cancer risk ratio. Other data quality objectives place the measured results into models with the non detected compounds being entered in as 1/2 the limit of detection which can provide a very significant error into the model.
Special care must be taken in the atmospheric analysis that includes different calibration models, detailed cleaning and certification procedures and enhanced quality assurance practices. This presentation discusses some suggestions to improve the TO-15 based guidance document to improve confidence in the results at these extremely low detection limits.
