[Determination of fipronil and its metabolites in feeds by stable isotope dilution ultra high performance liquid chromatography-tandem mass spectrometry].

A method based on ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established for the determination of fipronil and its metabolites in feeds. Sodium chloride was added to the samples after the ultrasonic extraction of pure water and acetonitrile, and then cleaned up by the QuEChERS method. The target analytes were separated on a Waters HSS T3 C18 column using methanol and water as mobile phases with gradient elution, and detected by a MS/MS system under negative electro-spry ionization (ESI-) and the multiple reaction monitoring (MRM) mode. The limits of detection (LODs) were 0.05 μg/kg, and the limits of quantification (LOQs) were 0.2 μg/kg. The linear correlation coefficients were more than 0.9998. The average recoveries ranged from 92.3% to 105.4% with RSDs no more than 2.3%. This method is suitable for the identification of fipronil and its metabolites in feeds because of its simplicity and high sensitivity.