Analysis of four sulfonylurea herbicides in cereals using modified Quick, Easy, Cheap, Effective, Rugged, and Safe sample preparation method coupled with liquid chromatography-tandem mass spectrometry

摘要

A modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) sample preparation method, coupled with liquid chromatography-electrospray ionization tandem mass spectrometry, has been developed for the simultaneous analysis of four commonly used sulfonylurea herbicides, ethoxysulfuron, halosulfuron-methyl, mesosulfuron-methyl and orthosulfamuron, in rice, maize, wheat and soybean. Adsorption of the analytes onto the primary-secondary amine used in the clean-up step was avoided by using 1% formic acid in acetonitrile as the extraction solvent to maintain the acidic herbicides in a non ionized state. Trueness studies were carried out at three levels (2.5, 25 and 250 mu g/kg for ethoxysulfuron and 5, 50 and 500 mu g/kg for the other three analytes). Promising trueness (70.2%-119.8%) was achieved for all herbicides in all matrices after clean-up, with relative standard deviations (RSDr) 18.6%. Satisfactory matrix effects (-19.7% to 14.8%) were also obtained. Good linearity of the calibration curves was achieved, with determination coefficients (r) = 0.9956, when the concentration of ethoxysulfuron was in the range 0.5-50 mu g/L. and that of the other three analytes was in the range 1.0-500 mu g/L. The RSDWR for within-laboratory reproducibility was 5.7%. The validated method was successfully used to analyze real samples. (C) 2018 Elsevier B.V. All rights reserved.