Dissipation kinetic study of fenazaquin in chilli and soil by LC-MS/MS.

Abstract

Dissipation and persistence of fenazaquin residues in chilli and soil were studied for 2 years following two applications of fenazaquin at 10-day interval. The limit of detection and limit of quantification were 0.003 and 0.01 mg kg-1. The mean initial deposits of fenazaquin 10 EC on green chilli fruits were found to be 0.74, 1.17, and 1.79 mg kg-1 after the application @ 125 (X dose), 156.25 (1.25X dose), and 250 (2X dose) g a.i. ha-1, respectively, during the first year followed by 0.78, 1.20, and 1.70 mg kg-1, respectively, during the next year. The mean initial deposits in soil were found to be 0.18, 0.25, and 0.44 mg kg-1 for the X, 1.25X, and 2X doses, respectively, during the first year and 0.19, 0.22, and 0.39 mg kg-1, respectively, during second year. The residues of fenazaquin in green chilli dissipated above 96% at 20 days in the three different doses whereas in red chilli, the residues were present on 25 days and at maturity, residues were below the limit of quantification (LOQ). In soil, the residues dissipated below the LOQ at 15 days for X and 1.25X while 20 days for the 2X dose, respectively. The half-life values in green chilli fruits and soil for the fenazaquin were found to be in the range of 3.22-3.93 days and 2.41-3.35 days, respectively. The waiting period was calculated to be 3, 5, and 8 days for green chilli after the application of fenazaquin at 25, 156.25, and 250 g a.i. ha-1, respectively.