Best Practices for Aroclor Screening of Drinking Water Compliance Samples by EPA 525.3

Data Quality, Management, and Review
Poster Presentation

Prepared by K. Leckrone
US EPA - Chicago Regional Laboratory, 536 S. Clark St,, ML-10C,, Chicago, IL, 60605, United States

Contact Information: [email protected]; 312-353-9268


PCBs in drinking water are regulated by the Safe Drinking Water Act (SDWA) via a two-step process. Water samples are first screened for PCBs as Aroclors following one of five available screening methods: EPA 505, 508, 508.1, 525.2, or 525.3. If screening results exceed regulatory screening limits, samples are re-analyzed for compliance purposes as decachlorobiphenyl using EPA 508A.

Four of the five screening methods require qualitative identification and quantitation of selected peaks from multicomponent Aroclor mixtures, with EPA 505, 508, and 508.1 using GC/ECD detection, and EPA 525.2 using GC/MS in scan mode. However, because each Aroclor is a complex multi-component analyte with overlapping chromatographic peaks, all these methods require separate multi-level calibrations of each of seven regulated Aroclor mixtures, and therefore are both labor-intensive and subject to analyst’s interpretation and skill in pattern recognition.

In EPA 525.3, approved in 2012, screening is based on 14 PCB congeners representative of the major components, by weight %, of the seven Aroclors listed in SDWA regulations. This results in a much simpler calibration and eliminates ambiguities associated with pattern recognition. EPA 525.3 also permits mass spectrometric detection in the more sensitive SIM mode. However, method performance data and sample results based on congeners are more difficult to interpret in the regulatory context of Aroclor screening detection limits and decachlorobiphenyl MCLs.

This summary presents an overview of Aroclor screening by EPA 525.3, including regulatory requirements, review of literature on the distribution and concentration of PCB congeners in the regulated Aroclors, best practices for reporting limits and method detection limits, and approaches to performance test (PT) studies. Method performance data in SIM and scan modes will be reviewed, and survey data will be presented regarding the extent of adoption of 525.3 for Aroclor screening.