Multi-residue Analysis of 34 Pesticides in Black Pepper by QuEChERS with d-SPE Vs. d-SLE Cleanup

Abstract

In this study, quick, easy, cheap, effective, rugged, and safe (QuEChERS) method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied and optimized in determination of 34 commonly used pesticides in black pepper. Two cleanup approaches including dispersive solid-phase extraction (d-SPE) and dispersive solid liquid extraction (d-SLE) were investigated and compared. The results showed that for d-SPE method, 26 target pesticides met the analytical recovery and RSD requirements (recoveries 60–120%, RSDs 2–28%) and LODs were 0.5–1 μg/kg, while for d-SLE method, 19 target pesticides met the analytical requirements (recoveries 60–117%, RSDs 3–24%) and the LODs were 0.5–2.5 μg/kg. Cleanup by d-SLE showed lower matrix effects and lower sensitivity due to the dilution factor, while d-SPE method could be applicable to more pesticides due to better sensitivity. It was therefore decided that d-SPE cleanup would be used in the final method for multi-residue analysis in black pepper. The method was developed and validated to determine the residues of 34 pesticides in 15 black pepper market samples collected from 11 different provinces in China. Four pesticides were detected, including clothianidin (0.02 mg/kg) that was detected in one sample and acetamiprid (