Sorghum bicolor L. Moench (Sorghum) is an annual plant in the grass family consuming as an animal fodder and alcoholic beverages. Chlorothalonil is a nonsystemic fungicide, widely used to control mold, mildew, bacteria and algae. This study investigated the dissipation pattern of chlorothalonil in grain and leaves of sorghum after spraying of chlorothalonil 75% wettable powder. The residue of pesticide was analyzed by GC-MS/MS (Shimadzu GCMS-TQ8040) equipped with SGE-BPX5 column (0.25 mm × 30 m, 0.25 μm ). Method limit of quantitation (MLOQ) were 0.01 mg/kg. The linearity of matrix-matched calibration curve (r2) was ≥0.99 at the calibration range of 0.0025-0.25 mg/kg. For the recovery test, 5 g of macerated grain or leaves of sorghum was treated with standard solutions at 10MLOQ and 50MLOQ levels and soaked with 10 mL of water adjusted to pH 1 by sulfuric acid for 10 min and extracted with 10 mL of acetonitrile by shaking (1 min). Then 4 g of MgSO4 and 1 g of NaCl were added, shaken for 1 min and centrifuged at 3,500 rpm for 5 min. The supernatant (1 mL) was purified with dispersive SPE (25 mg of PSA and 150 mg of MgSO4) by shaking for 1 min, and centrifuged at 13,000 rpm for 5 min before analysis. Recovery rates were in the range of 70-120% (RSD≤10%) at two spiked levels. After harvest, the grain and leaves sample were analyzed as for recovery test. For field trial, the pesticide was treated on 4 plots by different days before harvest (Plot 1: 50/40/30 days, Plot 2: 40/30/21 days, Plot 3: 30/21/14 days, Plot 4: 21/14/6 days before harvest) by three replicates. The maximum residues of grain were 3.45, 5.38, 11.74, 20.39 mg/kg in plot 1, 2, 3, 4 respectively, and 6.06, 9.00, 14.34, 32.23 mg/kg in leaves.

Dissipation pattern of fungicide chlorothalonil in Sorghum bicolor L. Moench after treatment of 75% wettable powder

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.