Analysis of Organochlorine Pesticides in Tomatoes Using a Modified QuEChERS Method Based on N-Doped Graphitized Carbon Coupled with GC-MS/MS

A modified QuEChERS protocol with a nitrogen-doped graphitized carbon derived from dicyandiamide sludge as a cleanup sorbent has been developed to determine 20 organochlorine pesticides in tomatoes using gas chromatography coupled to a triple-quadrupole mass analyzer. Compared with traditional QuEChERS adsorbents, N-doped graphitized carbon exhibited higher recoveries toward the target pesticides in tomatoes. And the modified protocol exhibited the advantages of environmental-friendly and low-cost. The use of dicyandiamide sludge to produce NGB as an adsorbent for QuEChERS opened up a new field for the comprehensive utilization of dicyandiamide waste. Under the optimum conditions, the modified method provided excellent linearity with correlation coefficient higher than 0.9980 and low limits of detection ranging from 0.001 to 0.1 μg/kg. The mean recoveries of the majority of pesticides in tomatoes ranged from 71.2 to 95.3% with relative standard deviation lower than 20%. Thus, the proposed protocol could be considered a good alternative for traditional QuEChERS method for pesticide analysis in agricultural vegetables.