Determination of fipronil and its metabolites in bird eggs by ultra-performance liquid chromatography-tandem mass spectrometry with dispersive solid phase extraction

Abstract

An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to determine fipronil and its metabolites (fipronil desulfinyl, fipronil sulfone and fipronil sulfide) in bird eggs. The samples were extracted with acetonitrile containing 0.1%(v/v) acetic acid, and then purified by a mixture of anhydrous sodium sulfate, octadecyl carbon silica gel (C18-N) sorbent and ethylenediamine-N-propyl carbon silica gel (NH2-PSA) sorbent. The analysis was performed by a UPLC-MS/MS system with Shim-pack GIST C18 column (50 mm×2.1 mm, 2 μm). The mobile phases consisted of methanol and 1 mmol/L ammonium acetate aqueous solution by gradient elution, and multiple reaction monitoring (MRM) mode with negative electrospray ionization was used. The effect of the dosages of anhydrous sodium sulfate, C18-N and NH2-PSA in cleaning-up agent was studied. The main influence factors and analytical conditions were modified. Four linear calibration curves were obtained with correlation coefficients r2 ≥ 0.9989. The recoveries were determined at three concentrations and ranged from 95.09%-103.26%. The limit of quantification (LOQ) was 0.2 μg/kg. It is suitable for the determination of fipronil and its metabolites in bird eggs.