This study was aimed at studying the rate of degradation of spiromesifen and its metabolite BSN2060 in Chinese matrimony vine using a kinetic model. The spray solution of pesticide was prepared by diluting the commercial product (20% SC) with water at 1:2000 (v/v) ratio and then sprayed on Chinese matrimony vine plants once (T-1) and twice (T-2) at seven day intervals. Samples were collected randomly from the experimental plots, at 0, 1, 3, 5 and 7 days after the last application and then dried using a hot air dry oven at 60? for 120 hours. The analytical methods for the test chemicals in fresh and dried samples were validated by a recovery investigation carried out at 0.1, 0.5 and 0.2, 1.0 mg/kg, respectively. Recovery of spiromesifen and its metabolite BSN2060 in fresh and dried samples ranged from 91.5 to 96.5% and 89.1 to 110.0%, respectively. Limits of quantitation (LOQs) for spiromesifen and its metabolite BSN2060 were 0.03 mg/kg for both chemicals. Residual concentrations of spiromesifen in fresh samples collected from T-1 and T-2 plots ranged from 1.72 to 2.09 mg/kg just after application and from 0.58 to 0.86 mg/kg at 7 days after last application, In case of dried samples, residue amounts of spiromesifen in both treatments were found to be from 2.27 to 2.99 mg/kg just after application and 0.84 to 1.16 mg/kg at 7 days after last application, indicating that residue change of spiromesifen have a tendency to decrease with time. However, no metabolite was detected from both fresh and dried samples. Half-lives of spiromesifen in T-1 and T-2 were estimated to be 4.8 and 5.6 days in fresh samples and 5.3 and 5.6 days in dried samples, respectively.

Degradation kinetics of spiromesifen and its metabolite BSN2060 residues in Chinese matrimony vine under outdoor conditions

248th National Meeting (2014)

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