Abstract: A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) pretreatment coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of fipronil and its metabolites in poultry-derived foods. Plackett-Burman design and Box-Behnken design were sequentially used to select and optimize the QuEChERS parameters with a significant influence on the recovery of analytes as well as their levels. The optimum parameters were obtained as follows: samples were extracted using acetonitrile, and the extract was salted out with a mixture of anhydrous magnesium sulfate and sodium chloride, and then purified by Z-Sep+ combined with multi-walled carbon nanotube (MWCNT) before being detected by UPLC-MS/MS and quantified by matrix-matched calibration. The results indicated that the average recoveries of fipronil, fipronil desulfinyl, fipronil sulfone and fipronil sulfide from eggs, chicken meat, and chicken liver at three different spiked levels were 78.9%–113.5%, with relative standard deviations (RSDs) of 2.10%–7.60%. The limit of detection (LOD) was 0.1–0.2 μg/kg, and the limit of quantitation (LOQ) was 0.5 μg/kg for all analytes. In the developed method, the matrix effects were effectively reduced. This method was simple, sensitive and accurate and could be used for rapid and quantitative determination of fipronil and its metabolites in poultry-derived foods.

Key words: QuEChERS; ultra-high performance liquid chromatography-tandem mass spectrometry; response surface methodology; fipronil and its metabolites; poultry-derived foods