Method development for simultaneous determination of 41 pesticides in rice using LC-MS/MS technique and its application for the analysis of 60 rice samples collected from Tehran market

For the first time, a multi-residue methodfor simultaneous determination of 41LC-amenable pesticides in rice, belonging to different chemical classes has been developed in Iran by LC-MS/MS. The pesticides were analyzed simultaneously in a single run using positive electrospray ionization with multiple reaction monitoring (MRM) after extraction with slightly modified QuEChERS method. The calibration curves for each analyte were linear in the concentration range 0.02–1.0μg/g with a correlation coefficient range between 0.993 and 0.999. The LOQ and LOD were0.025 μg/g and0.008μg/g respectively, for all 41 pesticides and the mean recoveries obtained for three fortification levels (0.025, 0.08 and 0.250μg/g) were71-119%with satisfactory precision (RSD<20%).The developed method was used to investigate the occurrence of pesticides in 30domestic and 30 imported rice samples collected from Tehran market.Fivecompounds were detected in 11domesticand 9importedpositive samples in concentration range from 0.032μg/g to 0.081μg/g and 0.028μg/g to 0.074μg/g, respectively. With the exception of prohibited pesticides, phosphmidon and TCMTB, three permitted pesticides, cinosulfuron, triadimenol and tricyclazole, found in positive rice samples were below MRLs established by Institute of Standards and Industrial Research of Iran (ISIRI).