Dissipation pattern of quinalphos in cauliflower, tomato and bean samples

Abstract

Quinalphos, an organothiophosphate chemical, is chiefly used as an insecticide. A field experiment was conducted at Bangladesh Agricultural Research Institute (BARI), to study the dissipation of quinalphos in tomato, cauliflower and bean samples when sprayed at its recommended dose and were collected from 0 (2 h after application) to 15 successive days. To determine the residual value of quinalphos, the samples were extracted in quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and run through a gas chromatography-electron capture detector (GC-ECD). Higher, middle and lower concentration calibration curves were obtained with linear correlation coefficient (r²) of 0.998, 0.995 and 0.993, respectively. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.009 and 0.027 μg mL⁻¹, respectively. The percentages of the recovery of quinalphos residues in spiked vegetable samples at three different levels (0.625, 2.5 and 5.0 μg mL⁻¹) were in the range of 74–86%. The amount of quinalphos residue in tomato, bean and cauliflower were in the range of 0.05–6.3, 0.05–3.1 and 0.06–6.5 μg g⁻¹ and dissipated below maximum residue limit (MRL; 0.20, 0.20 and 0.50 μg g⁻¹ in cauliflower, tomato and bean) value within 6, 4 and 7 days after application, respectively.