Lab Matters Winter 2019 - Page 11

INDUSTRY MATTERS PFAS Analysis: How to Minimize Contamination in Testing by Ken Rosnack, principal market development manager, Food and Environmental Markets, Waters Corporation PFAS (Per- and Polyfluoroalkyl substances) are anthropogenic chemicals found in a range of consumer goods and industrial processes. Common uses include firefighting foams 1 , water-resistant coatings, floor polishes, and oil resistant coatings for paper products approved for food contact. Testing laboratories have greater challenges today than ever before to meet the low detection limits and increased scope for PFAS defined by regulations. PFAS are ubiquitous and due to their widespread use and subsequent leaching are frequently detected in the environment, animals and humans. They are also difficult to keep out of laboratory background contamination. Due to their omnipresent, persistent nature and possible toxicity 2 , most regulatory agencies 3 worldwide monitor the use, occurrence and impact of traditional long-chain and the newer short-chain PFAS. These short-chain PFAS, such as “GenX 4 ,” are increasingly being used as replacements for the long-chain versions such as PFOS and PFOA. In addition to the cautions outlined above, using a PFC Analysis Kit 7 is recommended. It is comprised of components that replace Teflon ® items with PEEK counterparts and an isolator column to help delay any LC system interferences (see Figure 1). Relevant detection levels can be met utilizing this kit, a sensitive mass spectrometer (MS), and the sample preparation described in the guideline, regulatory or reference method being used. On a mid-tier MS, such as the Waters Xevo ™ TQ-S micro, an Oasis ™ WAX 8 solid phase extraction is recommended to enrich analytes by 100x to 250x. Should direct injection onto an MS be desired, a high performance MS such as the Waters ™ Xevo TQ-XS should be used. Kari Organtini, senior scientist and PFAS expert at Waters Corporation, standing next to the ACQUITY UPLC™ and the Xevo TQ-S micro MS system. Photo: Waters Corporation By following good laboratory practices to minimize contamination and by choosing a suitable analytical workflow, PFAS testing can become less challenging and more robust allowing routine, confident reporting of analytical results. n 1 2 3 4 5 6 7 8 Influence of Contaminated Drinking Water on Perfluoroalkyl Acid Levels in Human Serum – A Case Study from Uppsala, Sweden, Irina Gyllenhammar et.al, https://www.sciencedirect. com/science/article/pii/S0013935115001656, Accessed 04 December 2018 PFAS Health Effects, Source: https://www.atsdr.cdc.gov/pfas/ health-effects.html, Accessed 04 December 2018. PFAS Laws and Regulations, Source: https://www.epa.gov/pfas/ pfas-laws-and-regulations, Accessed 04 December 2018. “GenX” is a brand name for a chemical process that utilizes FRD-903 to produce FRD-902 and E1. See GenX Wikipedia Entry, Source: https://en.wikipedia.org/wiki/GenX, Accessed 04 December 2018. Region 5 CRL Methods for the Analysis of Polyfluorinated Compounds (PFCs) Using a Quick Sample Extraction / Preparation Followed by UPLC/MS/MS Analysis, Lawrence B. Zintek et.al., National Environmental Monitoring Conference Presentation 2017. Teflon is a registered trademark of the Chemours Company used for polytetrafluoroethylene. Analysis of Legacy and Emerging Perfluorinated Alkyl Substances (PFAS) in Environmental Water Samples Using Solid Phase Extraction (SPE) and LC-MS/MS (PFC Kit Waters Part #176001744), Organtini et.al. Available from: http://www. waters.com/webassets/cms/library/docs/720006471en.pdf. OASIS WAX Cartridge Product Information Page, Source: http://www.waters.com/waters/partDetail. htm?partNumber=186002493, Accessed 04 December 2018. Waters Corporation is a platinum level sustaining member of APHL. For routine monitoring and research purposes, detection of PFAS to the ng/L, ng/kg or part-per-trillion (ppt) level requires the use of LC/MS/MS. However, there are many common sources 5 of PFAS contamination making it difficult to routinely achieve such low level analysis. Although complete avoidance of PFAS is impossible, steps can be taken to minimize background contributions. In the field, caution should be taken to avoid Teflon ®6 containing materials such as waterproof clothing, plastic clipboards, waterproof notebooks and chemical ice packs. In the laboratory, items to avoid include sticky notes, certain glass disposable pipettes, aluminum foil, vial caps with Teflon seals and LDPE containers. It is recommended that all laboratory supplies be checked for PFAS contamination before use in the analysis. PEEK Tubing System Isolator Column Figure 1: PFC Analysis Kit installed in the Waters ACQUITY UPLC showing main components. Photo: Waters Corporation PublicHealthLabs @APHL APHL.org Winter 2019 LAB MATTERS 9