Development, validation, and use of a monitoring method for fipronil and its metabolites in chicken eggs by QuEChERS with online-SPE-LC-Q/Orbitrap analysis.

Abstract

The residues of fipronil and its metabolites in chicken eggs pose a threat to human health, so regular monitoring is necessary. However, the pretreatments of the existing detection methods are complex and time-consuming. A simple and streamlined pretreatment method is needed to improve the detection efficiency. A rapid, efficient, and facile approach employing QuEChERS with online solid-phase extraction liquid chromatography tandem Q-Exactive Orbitrap high resolution mass spectrometry (online-SPE-LC-HRMS) was established and evaluated for the determination of fipronil, fipronil-desulfinyl, fipronil-sulfone and fipronil-sulfide in chicken eggs. An improved sample preparation technique combining QuEChERS and online-SPE was developed. Negative targeted ion fragmentation scanning (t-MS2 ) and targeted-selected ion monitoring (t-SIM) of the HRMS were adopted to identify and quantify the target analytes. The proposed pretreatment method took a few steps in < 13 min to achieve excellent recoveries and negligible interference. High selectivity was acquired with the adoption of Q/Orbitrap HRMS. The LOQ of the analytes was 2.5 μg kg-1 , meeting the detection requirements of the MRL enacted by the Codex Alimentarius Commission (CAC), Japan and USA for the sum of fipronil and its metabolites. Extraction recoveries at three spiked concentration levels were within 84.56-93.84% with RSD ≤ 5.87%. The established method is efficient and easy to operate and displays satisfactory LOQs, recoveries, accuracy and precision. This approach serves as a reference method for monitoring eggs while providing potential solutions for fipronil determination in more complicated matrices.