Development and Application of a Liquid Chromatography-Tandem Mass Spectrometry Method for the Analysis of 20 Perfluoroalkyl Substances in Fruit and Vegetables at Sub-Parts-per-Trillion Levels

Abstract

In response to the European Food Safety Authority's establishment of a tolerable weekly intake (TWI) for the sum of PFOA, PFNA, PFHxS, and PFOS, a method was developed to quantify and confirm 20 PFASs at the sub-parts-per-trillion level in fruit and vegetables. Improved sensitivity was achieved by (i) increasing the sample intake, (ii) decreasing the solvent volume in the final extract, and (iii) using a highly sensitive mass spectrometer. Except for PFTrDA, target PFASs could be quantitatively determined with an apparent recovery of 90-119%, limits of quantitation down to 0.5 ng/kg, and a relative standard deviation under within-laboratory reproducibility conditions of <28%. The method was successfully applied to 215 fruit and vegetable samples obtained from local grocery stores and markets. Leafy vegetables prove to be the main vegetable category responsible to PFAS exposure, mainly of PFOA, followed by PFHpA and PFHxA.

Keywords: LC−MS/MS; PFASs; exposure; food; validation.

Figure 1

MRM chromatogram of all 20 PFASs in a spiked potato sample at 10 ng/kg. PFOSA is not visible in the current view but elutes after 10 minutes.

Figure 2

Schematic representation of detected PFAS concentrations in the fruit and vegetable samples, per PFAS. Detected PFASs are individual observations, with no sum-concentrations of different samples. n = number of occasions that a specific PFAS was detected in the samples (number of samples = 215).

Figure 3

Schematic representation of detected PFAS concentrations in the fruit and vegetable samples, per matrix category. Detected PFASs are individual observations, no sum-concentrations of different PFASs. n = number of occasions that a PFAS was detected in the samples (number of samples = 215).