Dissipation rates, residue distribution and dietary risk assessment of isoprothiolane and tebuconazole in paddy field using UPLC-MS/MS

Abstract

ABSTRACT A QuEChERS method was developed to simultaneously quantify isoprothiolane and tebuconazole in paddy field samples by using UPLC-MS/MS. The method has been successfully applied in determining isoprothiolane and tebuconazole in brown rice, polished rice, rice husk and straw. The dissipation behaviour of isoprothiolane and tebuconazole in rice followed first-order kinetics, with a linear correlation coefficient of 0.8283 to 0.9877. The degradation half-life of isoprothiolane in rice grain was 6.5–25.7 days, whereas that of tebuconazole was 7.5–13.9 days. The highest levels of isoprothiolane and tebuconazole in brown rice, with a preharvest interval (PHI) of 28 days, were 0.327 and 0.885 mg/kg. Rice bran accounted for the largest proportion of isoprothiolane and tebuconazole in rice grain with 43.1% and 41.2%, respectively. Risk quotients (RQs) of isoprothiolane and tebuconazole in brown rice were 3.0% and 90.6%, respectively, indicating a low health risk to consumers.