Determination of 16 Carbamate Pesticide Residues in High-Sulfur Vegetables by UHPLC-MS/MS after Preparation of Sample with QuEChERS

A method based on UHPLC-MS/MS after preparation of sample with QuEChERS was developed for simultaneous determination of 16 carbamate pesticide residues in 6 high-sulfur vegetables, including onion, onionleek, Chinese chive, garlic scape, ginger and garlic. Samples were extracted with frozen acetonitrile and salted out with anhydrous magnesium sulfate and sodium chloride. The upper extract was purified by dispersion solid phase extraction with anhydrous magnesium, PSA and C₁₈, the analytes were determined under the optimized working conditions of the instrument. In UHPLC analysis, Waters ACQUITYUPLC BEH C₁₈ chromatographic column was adopted as stationary phase, and the mixed solution consisted of acetonitrile solution containing 0.1% formic acid (A) and 0.1% formic acid solution (B) with various ratios was used as mobile pahse for gradient elution. MS analysis was made under ESI⁺ and MRM mode. Matrix-matched standard solution series was prepared for making the standard curve, and results showed that the mass concentrations of 16 pesticides had linearity relationships with their respective peak areas in the definite ranges, with detection limits in the range of 0.1-20 μg·kg^-1. Recovery test was made on garlic scape at the 3 concentration levels, giving recoveries in the range of 65.7%-112%, and RSDs (n=6) of the determined values were ranged from 1.5% to 11%. The proposed method was used for the analysis to the 34 batches of high-sulfur vegetable samples, diethofencarb was found in 2 batches of onions samples with mass fraction of 0.040, 0.178 mg·kg^-1, and fenobucarb was detected in a batch of ginger sample with mass fraction of 0.092 mg·kg^-1.