Aug 05, 2021

The US EPA has an interest in requiring higher levels of accuracy for PCB compliance testing to support National Pollution Discharge Elimination System (NPDES) requirements. The EPA thus approached SGS to validate a new high-accuracy method for reporting individual PCB congeners by gas chromatography-mass spectrometry. The resulting PCB Method 1628 draft is posted for comment at EPA PCB congener low resolution method. The EPA stated that while Method 1628 is not yet approved at 40 CFR 136, the EPA considers the method suitable for release and states authorized to issue NPDES permits may elect to use this method pending nationwide approval as a replacement for EPA Method 608.3. Our center of excellence mass spectrometry laboratory, SGS AXYS, has developed many methods for the EPA in the past, including EPA Method 1668 for sensitive PCB congener measurement by high-resolution mass spectrometry. We bring a unique combination of scientific expertise, stable of instruments, and experience in the specific level of detail that has helped the EPA bring many mass spectrometric methods to life. In addition, our laboratory network expertise meant we were also able to participate in the multi-laboratory validation for this method at our Wilmington, NC laboratory.

Polychlorinated biphenyls or PCBs are a family of persistent organic pollutants that were used in multiple industrial applications such as capacitors and transformers, paint dyes, and construction materials. Though production of PCBs in North America ended in 1977, their stability in the environment has allowed them to persist and spread, including being found in areas far away from of production and use, such as the high Arctic. While most PCBs were manufactured in complex Aroclor mixtures, they are also by-products in the manufacture and use of any materials containing chlorine, most notably in paint and pigments. PCBs are persistent, bioaccumulative, and toxic. They are listed in the Stockholm convention, and considered a probable carcinogen. Humans exposed to PCBs have shown development delays, immune system suppression, and quantifiable behavioral problems. Of the 209 PCBs, 13 of them exhibit dioxin-like toxicity.

Draft EPA Method 1628 identifies and reports all 209 PCBs and homolog totals by levels of chlorination using isotope dilution and modified isotope dilution gas chromatography-mass spectrometry. This new method measures individual PCB congeners, not an estimated aroclor pattern. Aroclor methods, while widely used, are based on matching a chromatographic pattern generated from Aroclor mixtures. They are prone to many issues including interferences from other chlorinated pollutants. Importantly, as PCBs transform in the environment over time (weathering), the patterns become less representative over time. Also, as more non-aroclor PCBs from paints, pigments and other sources enter the environment, aroclor-based methods can result in false negatives and low bias. EPA 1628 uses isotope dilution quantification and GC-MS to report each PCB individually or as coeluting mixtures. Historically, the only alternative to measuring individual PCB congeners was EPA 1668, a high-resolution mass spectrometric method. While this method remains the gold-standard, the equipment and technical requirements, low backgrounds and high cost has meant congener methods were not widely applicable for routine PCB monitoring. EPA 1628 is a middle ground PCB identification method, sensitive and specific enough for superior data quality, but still accessible for routine analysis at typical full-service environmental laboratories.

“We are excited to continue our pioneering of new methods for the US EPA and increasing the standard of evaluation of toxic chemicals in our environment. At SGS we seek to create a more sustainable and healthy future by creating a better, safer, more interconnected world,” said Marcus Maguire, Vice President, Environment, Industries and Environment, SGS North America.

For more information contact:
Bharat Chandramouli,
Environmental Laboratory Product Manager
+1 (250) 655-5813

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