Method validation, household cooking effect on pesticide residues, and evaluation of processing factors in rice

An experiment shows the reduction of pesticide residues using common household cooking techniques. The estimation of seven pesticides was performed using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method with liquid chromatography tandem mass spectrometry (LC-MS/MS) and Gas Chromatography Tandem Mass Spectrometry (GC-MS/MS) in rice. The method validation study was carried out with linearity (R2 > 0.99), average recoveries of all pesticides ranged from 82.00 to 102.36%, with a precision of 3.78–6.84% and 1.25–7.24% inter and intraday, respectively. The limit of quantification was 0.01 mg/kg for all tested pesticides. The processing factors (PF) were calculated for seven pesticides from various processing of rice grains collected from the plot applied with pre-mixed pesticides. To decrease pesticide residues in rice grains, processing techniques, including pressure cooking rice, traditional cooking without drained water, and traditional cooking with excess water, were investigated. The overall percent reductions of fipronil, imidacloprid, pymetrozine, flonicamid, bifenthrin, clothianidin, and cartap hydrochloride were 71.96–90.01, 69.07–86.60, 79.78–91.05, 69.37–84.08, 68.95–88.77, 71.73–85.44, and 61.23–89.67 percent, respectively. The calculated PFs for all pesticides were less than 1, indicating that the residue magnitudes of all pesticides decreased after each process and all the processing techniques were effective. The data showed that the traditional technique of cooking rice with excess water was the most efficient technique to reduce pesticides, proving effective in minimizing pesticide residues and reducing human exposure to pesticides through diet.