Polar pesticides in food of animal origin: interlaboratory validation to evaluate method fitness-for-purpose of official control

Abstract

The present work reports on the design, execution and evaluation of results of an interlaboratory validation study aimed at verifying the fitness-for-purpose of a LC-MS/MS method for the detection of polar pesticides in food of animal origin in official control and monitoring programmes. To this scope, five participant laboratories, with relevant expertise, were recruited. After passing a pre-trial test, the participants were asked to analyse test samples of bovine fat, chicken eggs and cow’s milk, contaminated with 11 polar pesticides (group A: Aminomethyl phosphonic acid (AMPA), cyanuric acid, ethephon, glyphosate, fosetyl aluminium, 2-hydroxyethyphosphonic acid (HEPA), maleic hydrazide, N-acetyl-glyphosate, group B: N-acetyl glufosinate (NAG), 3-methylphosphinicopropionic acid (MPP) and glufosinate ammonium) at two different levels (0.05 and 0.25 mg/kg⁻¹ and 0.01 and 0.05 mg/kg⁻¹ for group A and B respectively. The method was based on acidified methanol/water extraction followed by dSPE clean up with C18 sorbent. For LC-MS/MS analysis isotopically labelled standards were used for all targeted analytes. With a couple of exceptions, average recoveries ranged from 85% to 110%, with repeatability (RSDr) ranging from 3% to 25%, and reproducibility (RSD_R) from 4% to 26%. The assessment by different laboratories provided also insights on key factors impacting method performance characteristics and its implementation by new users.

Keywords:

• Inter-laboratory validation
• chromatography - LC/MS
• pesticide residues
• animal products
• eggs
• milk

Acknowledgments

The authors thank all participants of the study including: Istituto Zooprofilattico Sperimentale delle Venezie; Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise "Giuseppe Caporale"; Istituto Zooprofilattico Sperimentale della Sardegna " Giuseppe Pegreffi"; University of Chemistry and Technology, Prague; Wageningen Food Safety Research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Ministero della Salute (IZS UM 07/19 RC).