Development of precise GC-EI-MS method to determine the residual fipronil and its metabolites in chicken egg.

Fipronil is a highly toxic insecticide, and fipronil egg scandal greatly threaten people's health. Herein, a precise and reliable method was developed for the determination of fipronil and three metabolites in chicken egg by GC-EI-MS. Sample pretreatment took about 20 min and baseline separation of four analytes were realized within 12 min by GC-MS. Moreover, the limits of detection were 0.2-0.5 ng g-1 and the limits of quantitation was 0.5-1 ng g-1 with relative standard deviations (RSDs) lower that 3.32%. Satisfactory recoveries were get in the range of 81.16-103.57% for three levels of spiked samples. Finally, the developed method has been applied for the analysis of egg samples from four sources. Results showed that fipronil and fipronil-sulfone were detected in three samples, while fipronil-desulfinyl and fipronil-sulfide were totally absent. The method showed great promising in quantification of fipronil and its metabolites in food safety affairs.