Analysis of Ultra-short Chain PFAS by Reversed-Phase LC/MS/MS

Per- and Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by Y. Li
Eurofins Eaton Analytical, 110 South Hill Street, South Bend, Indiana, 46617, United States


Contact Information: [email protected]; 574-472-5562

ABSTRACT

Ultra-short-chain (C1-C3) polyfluoroalkyl substances (PFAS) are a subset of widespread PFAS. There is a rising concern and interest regarding ultra-short chain PFAS due to their abundant presence in the environment, human bodies, and potable water as well. Because of the high acidity, solubility. and mobility, ultra-short chain PFAS also challenge common PFAS treatment techniques such as GAC and ion exchange resins which cannot effectively retain C1-C3 PFAS. Although there is growing evidence of the toxicity of some ultra-short chain PFAS, the effects of C1-C3 PFAS on human health and ecosystems remain largely unknown.

C1-C3 PFAS pose a challenge to traditional reversed-phase liquid chromatography/tandem mass spectrometry (RPLC/MS/MS) widely used in analysis of short-chain and long-chain PFAS due to insufficient chromatographic retention. Therefore, ultra-short PFAS methods often involve ion chromatography (IC), hydrophilic interaction liquid chromatography (HILIC), or hybrid HILIC/ion exchange (IX). Sample quenching is often required to protect HILIC or hybrid LILIC/IX columns from chlorine oxidation.

This presentation will introduce an alternative RPLC/MS/MS method for analysis of ultra-short chain PFAS, including trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), trifluoromethanesulfonic acid (TFMS), perfluoroethanesulfonic acid (PFEtS), perfluoropropanesulfonic acid (PFPrS), and bis(trifluoromethane)sulfonamide (TFSI). Under the optimized instrument conditions, this direct aqueous injection (DAI) RPLC/MS/MS method provides sufficient chromatographic retention and sensitive detection of these ultra-short chain PFAS. The method also uses isotopically labeled native ultra-short chain PFAS as the internal standards to improve accuracy and precision and tolerance of matrix interferences as well. Besides the initial demonstration of capability, this work will present the occurrence levels of the ultra-short chain PFAS in different aqueous sample matrices. The advantages of using RPLC include, but not limited to, removed the need for sample quenching, improved applicability to a wider pH range of samples, increased column lifetime, and reduced instrument changeover time.