Development of a Pass-through SPE Cartridge for the Rapid Determination of Fipronil and Its Metabolites in Chicken Eggs by LC-MS/MS

In this work, a novel pass-through cleanup cartridge was developed for the rapid determination of fipronil and its metabolites in chicken eggs by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The systemic elimination experiments on pigments, lipids, proteins, and so on were performed, and then a multi-function SPE cartridge containing three sorbents (PestiCarb, Alumina-N, and COOH) was designed. Using this cartridge, a simple cleanup procedure with the ideal elimination effects was achieved by gravity in less than 1 min. The involved LC-MS/MS method provided satisfactory performance. The tested recoveries were in the range of 78.6–87.1% with the relative standard deviations (RSDs) less than 8.3%. The limits of quantitation (LOQs) of fipronil, fipronil-desulfinyl, fipronil-sulfone, and fipronil-sulfide were 1, 0.5, 1, and 0.5 μg/kg, respectively. This method was successfully applied to detect some chicken eggs from local markets and farms. A positive sample of 5.3 μg/kg fipronil and 31.8 μg/kg fipronil-sulfone was found and the potential risk root was traced. In the future, a specific device equipped with a lot of the above-developed cartridges could be designed for the rapid and high-throughput cleanup. It would be helpful to reduce the manual labor and save the time of sample pretreatment.