Evaluation of Chromatographic Separation, with a Focus on LC-MS/MS, for the Determination of Stereoisomeric Cypermethrin and Other Synthetic Pyrethroids in Apples

Pyrethroids, synthetic analogues of natural pyrethrins, are extensively used in agriculture and household pest control due to their high insecticidal activity and relatively low toxicity to mammals. Due to the presence of multiple chiral centres, many pyrethroids exist as complex mixtures of stereoisomers with significantly different biological activities, toxicities, and environmental behaviours. Consequently, accurate determination of these stereoisomeric forms, particularly compounds such as cypermethrin, is critical for food safety monitoring. Determining pyrethroid residues in food matrices presents a significant analytical challenge due to the structural diversity and stereochemical complexity of these compounds. This study presents the development of an analytical method for determining the stereoisomeric forms of cypermethrin and other synthetic pyrethroids in food matrices using both LC-MS/MS and GC-MS/MS techniques. The method meets the performance criteria outlined in SANTE/11312/2021 v2, demonstrating satisfactory recovery rates (91.6%), precision (RSDR 1.9%), and low limits of quantification (LOQ 0.010 µg/kg) for the quantification of alpha-cypermethrin. This approach offers a reliable tool for regulatory monitoring and risk assessment of pyrethroid residues, especially those with complex stereochemistry.