A Strategy for Ultra Low-Level Detection and Quantification of Short- and Long- Chain Per- and Polyfluoroalkyl Substances (PFAS) by Direct Injection LC-MS/MS

Polyfluoroalkyl Substances (PFAS) in the Environment (Session 2)
Oral Presentation

Prepared by E. George1, M. Krajewski2, O. Scheibner3
1 - Thermo Fisher Scientific, 355 River Oaks Pkwy, San Jose, CA, 95134, United States
2 - Thermo Fisher Scientific, , Germering, DE, Germany
3 - Thermo Fisher Scientific, , Dreieich, DE, Germany


Contact Information: [email protected]; 408-300-4267

ABSTRACT

PFAS were first developed in the 1940s and have been used in numerous industrial and commercial products that required thermal and chemical stability, water resistance, and stain resistance. Awareness of PFAS contamination in the environment first emerged in the late 1990s following developments in analytical instrumentation which enhanced detection of PFAS. Current regulations present significant analytical challenges with respect to low limits of quantification required for both short- and long-chain PFAS in a wide variety of matrices.

In this work, an optimized LC-MS/MS method for the direct injection and detection of long- and short-chain PFAS is presented. The method utilized a combination of a Thermo Scientific Acclaim™ Polar Advantage (PA) column, a Thermo Scientific TSQ Altis™ triple quadrupole mass spectrometer, and a Thermo Scientific Vanquish™ Core™ HPLC system with a user defined custom injection program (CIP). CIPs were used to create sample and mobile phase plugs within a 1 mL sample loop, allowing mixing of the plugs prior to injection. Chromatographic optimization was performed with PFAS standards (ranging from C4 to C14) dissolved in a) aqueous mobile phase containing 5mM ammonium formate and 0.1% formic acid and b) 96% methanol. The CIP program for the aqueous sample used a total injection volume of 225 uL. The 96% methanol standards used a total injection volume of 75uL segmented into 3x25uL plugs separated by aqueous mobile phase plugs. In both cases, the C4-C14 PFAS showed excellent peak shape. Calibration curves ranging from 1 to 200 ng/L prepared in 96% methanol had r2 > 0.995 with LODs between 1-10 ng/L. Calibration curves ranging from 1 to 100 ng/L prepared in aqueous mobile phase had r2> 0.960 with LODs <1 ng/L up to 5 ng/L. The method was applied to environmental water and soil extracts and demonstrated to be easy to use and fit for purpose.