Evaluation of washing and heating processes on the residues of selected pesticides in rice using liquid chromatography-mass spectrometry

In this research a validated and effective method was developed for simultaneous analysis of 60 pesticides in rice, using liquid chromatography-mass spectrometry (LC-MS/MS), then, the effects of washing and heating processes on residues of studied pesticides were investigated. Extraction was performed by the original QuEChERS method. The pesticides were analyzed simultaneously in a single run with a multiple reaction monitoring (MRM) method. The validation study was performed based on the SANTE 2019 guideline. The method was tested to assess for linearity, trueness, precision, specificity, limit of quantification (LOQ) and limit of detection (LOD). The results showed that the calibration curves for all studied compounds were linear with a coefficient of determination (R2) ranged between 0.984 - 1.000. The mean recoveries obtained for three fortification levels (25, 250, 1000 ng/g) were 76.4 - 110.2 % with satisfactory precision (RSD ranged between 2.8 – 16.7%. After analysis of treated rice samples with investigated pesticides, the results indicated that both of washing and heating processes, in individual and combinational cases, significantly reduced the amounts of studied pesticides.