Multi-Approach Data Processing Workflow to Help Closing the Mass Balance of PFAS in the Environment

Emerging Environmental Applications for High Resolution Mass Spectrometry
Oral Presentation

Prepared by O. Shrestha, J. Dahl, T. Matsubara, R. Marfil-Vega
Shimadzu Scientific Instruments, 10330 Old Columbia Rd, Columbia, MD, 21046, United States


Contact Information: [email protected]; 410-910-0884

ABSTRACT

An untargeted LC-MS method employing a sensitive, high-mass-accuracy quadrupole time-of-flight (QToF) instrument was used to participate in the PFAS NTA Interlaboratory Study organized by the National Institute of Standards and Technology (NIST) in 2024. Coupled with a novel data-processing approach, this technique enables comprehensive non-targeted screening of PFAS that helps scientists with closing the mass balance of PFAS in the environment.
Three unknown samples (A, B, and C) obtained from NIST were analyzed to identify PFAS following the guidelines for the 2024NTA ILS. A data-dependent acquisition (DDA) method in both positive and negative ionization modes was implement using QToF mass spectrometry to expand the chemical space covered with the method. Multi-approach data processing included identifying PFAS compounds using NIST Library Match, the NIST suspect list, FluoroMatch and LabSolutions. This systematic and complimentary approach allowed for accurate analysis and identification of PFAS analytes in the unknown samples.
The EPA 1633 PFAS standard mix was used to validate m/z trigger settings for the DDA method. The NIST MS2 library was converted into a software-compatible format to facilitate accurate spectrum matching. Identification through NIST Suspect Match relied on common product ions, neutral losses, and isotope Score, with a mass error threshold of less than 5 ppm. FluoroMatch analysis incorporated its built-in PFAS library and algorithms, utilizing Kendrick Mass Defect plots to identify PFAS and related families. Results were dereplicated, and PFAS were identified and scored according to NIST-defined criteria. For samples A, B, and C, there were 40, 57, and 105 negative PFAS matches, respectively, and 9, 44, and 29 positive matches. In this presentation we will demonstrate the workflow and how the comprehensive multi-data approach benefits the PFAS identification.