Determination of Pesticides and Their Metabolites in Eggs by Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometry

A method for simultaneous determination of several pesticides and their metabolites in eggs by ultra-high performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS) was proposed. The egg sample (2.0 g) was extracted for 10 min with 10 mL of acetonitrile by ultrasound at low temperature, and then centrifuged after adding 2.0 g of anhydrous sodium sulfate and 1.0 g of sodium chloride. 2 mL of the supernatant was purified with QuEChERS adsorbent containing 25 mg of C₁₈, and 1.0 mL of the purification solution was passed through Oasis^® PRiME HLB solid phase extraction column. The effluent was collected and diluted to 2.0 mL with 10% (volume fraction) acetonitrile solution. The obtained solution was separated on a Waters Acquity UPLC^® BEH C₁₈ column, and gradient elution was performed using acetonitrile and 0.1% (volume fraction) formic acid solution at different volume ratios as mobile phase. ESI⁺ mode and MRM mode were adopted in MS analysis. Characteristic ions and retention time were used for qualitative analysis and standard curve external standard method was used for quantitative analysis. As shown by the results, linear ranges of the standard curves of pesticides and its metabolites were all 0.5-20.0 μg·L^-1, with detection limits (3S/N) in the range of 0.038 1-0.893 μg·kg^-1. Test for recovery was carried out according to the standard addition method, giving results in the range of 74.0%-128%, with RSDs (n=6) of the determined values in the range of 0.54%-10%.