Simultaneous determination of thiacloprid and its five metabolites in vegetables and flowers using QuEChERS combined with HPLC-MS/MS

Neonicotinoids have recently been banned in the European Union due to concerns about their environmental safety. Thiacloprid is a neonicotinoid, and is frequently used in agricultural pest control. However, the lack of quantitative methods for assessing its multiple metabolites has made it difficult to perform a comprehensive safety assessment. Therefore, we established an analytical method for effectively determining thiacloprid and its five metabolites in vegetables and flowers using QuEChERS-HPLC-MS/MS. The samples were extracted with acidified acetonitrile (containing 0.5% acetic acid) and were cleaned with graphitised carbon black (GCB) and octadecylsilane (C18) before the residue analysis. This method provided linearity ranging from 2–2000 μg kg−1, and its linear regression coefficients exceeded 0.995. Limits of Quantitation (LOQs) are achieved at 2 μg kg−1， and Limits of Detection (LODs) ranged from 0.09–0.80 μg kg−1. The method was validated on seven matrices spiked at 2, 200, and 2000 μg kg−1. Average recoveries ranged from 77–119%, with an intra-day Relative Standard Deviation (RSDr) of 1.5–13.4% and an inter-day Relative Standard Deviation (RSDR) of 0.9–14.4%. This method was used on cucumbers sprayed with thiacloprid and 19 types of flower samples collected from the field, after which thiacloprid and several of its metabolites were detected.