Development of a fast method for the determination of pesticide multiresidues in tomatoes using QuEChERS and GC-MS/MS

Here we describe the improvement of pesticide residue extraction from tomatoes by an improved QuEChERS method. Through Plackett-Burman design, 4 significant variables out of 11 potential variables were identified that could influence the relative deviation of measurements. The 11 variables were: amount of sample, C-18, Na2SO4, NaCl, MgSO4, NaAc, GCB (graphitized carbon black), and PSA (primary-secondary amine); ACN volume; percentage of FA (formic acid); and centrifugation time. The amounts of GCB, Na2SO4, PSA and sample were significant variables, which were further optimized using a Box-Behnken design to predict the optimum extraction conditions. The method presented recoveries between 72.5 and 119.7%, with relative standard deviations ranging from 1.17 to 14.62% for all real samples spiked with pesticides at three different fortification levels. Overall, methods met the requirements of national standard for pesticide residue analysis. The results indicate that the improved QuEChERS method is suitable for the routine monitoring of 20 pesticides which often are detected in tomato samples.