Inadequate definition of the limit of quantification used for the analysis of perfluoroalkyl substances in food by liquid chromatography-tandem mass spectrometry may compromise the reliability of the data requested by the European regulation.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a widespread technology used for the quantitative determination of per- and polyfluoroalkyl substances (PFAS) in foodstuff. Specifically, LC-MS/MS offers an attractive performance by combining the sensitivity and selectivity required by the European Union for testing perfluorooctane sulfonic acid, perfluorooctanoic acid, perfluorononanoic acid, and perfluorohexane sulfonic acid with maximum limits of quantification (LOQ) in the sub-parts-per-billion (μg/kg) or the parts-per-trillion (ng/kg) domains. In this article, we highlight the important diversity in LOQ definitions applied in LC-MS/MS methods described in the literature that raise concerns about the capability of some of those to generate reliable data requested by the European regulation. Here, we point out the risk of false response or misquantification if the criteria for assessing LOQ suffer from a lack of rigor. We emphasize the need to use PFAS-free samples spiked with the analyte(s) of interest and the application of identification criteria according to official documents for a sound measurement of the LOQ.
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