Rapid screening of fipronil and its metabolites in egg and egg products by solid phase extraction-liquid chromatography-quadrupole time-of-flight mass spectrometry

Abstract

A method for rapid screening of fipronil and its metabolites in egg and egg products was developed by liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC-QTOF MS). The samples were extracted by acid-acetonitrile, cleaned up by PRiME HLB SPE. The separation was performed on a Poroshell 120 EC C18 column (150 mm×3 mm, 2.7 μm) with gradient elution using water and acetonitrile as mobile phases. The target compounds were monitored under negative ionization mode with electrospray ionization (ESI) source and two databases of accurate mass and fragment ions were created. The matrix effects in four kinds of egg and egg products were considered and the quantification was carried out by internal standard method. The results demonstrated that the linear ranges were from 0.1 to 5 μg/L with good correlation coefficients (r2>0.99). The limits of detection (LODs, S/N>3) and limits of quantitation (LOQs, S/N>10) were 0.2 μg/kg and 1 μg/kg, respectively. The recoveries of fipronil and its metabolites in different matrixes spiked with 1, 2 and 5 μg/kg varied from 82.6%-98.1%, and the relative standard deviations (RSDs) were between 3.8%-9.9% (n=6). The method can effectively correct the ionization suppression. It is sensitive, accurate and suitable for the rapid screening of fipronil, fipronil sulfide, fipronil sulfone and fipronil desulfinyl in egg, egg noodle, cake and mayonnaise.