Identifying False Positives Caused by Sporadic PFAS Contamination During Routine PFAS Analysis

Presented by Lawrence Zintek, USEPA Region 5 Laboratory Services and Applied Science Division
Contact Information: [email protected]

ABSTRACT

Through extensive testing of several brands and part numbers of various consumables required for PFAS sample collection, preparation, and analysis for this analysis, it has been determined that obtaining consistently trace-level, PFAS-free products is unlikely. However, the sporadic PFAS contamination currently observed is predominately low-level (at or near the reporting limit) and only appears to occur in <1% of consumables tested. Requiring duplicate sample collection, preparation, and analysis provides the needed assurance that the PFAS values reported are both precise, accurate and identify false positives. The replicate field sample data has to be evaluated by the user to identify biased high or false positive results. Since soil sample matrices are not homogeneous a discrepancy between soil samples is more likely to occur. It is required to also consider that replicate PFAS samples are co-located and data variability between replicates may occur based on the co-located nature of replicate PFAS sampling. Since PFAS contamination has become an issue with PFAS analysis all field samples are taken in duplicates to identify false positives.