Determination and dissipation of fipronil and its metabolites in/on sugarcane crop
Fipronil has label claim for managing shoot borer and root borer of sugarcane. The dissipation and metabolism of fipronil in/on sugarcane crop have been studied under tropical field condition by employing a modified quick, easy, cheap, effective, rugged and safe sample preparation method and gas chromatography equipped with electron capture detector. The method could provide 90.27–98.97% recoveries of target analytes from cane leaves and stem with relative standard deviations of less than 5%. The sulphide, desulfinyl and sulfone metabolites of fipronil were detected along with the parent compound even in the 0-day samples of sugarcane leaves and stem collected 2 h post-foliar spraying. The total residues comprising fipronil and its three major metabolites got dissipated to 4.366 µg/g from the initial deposit of 12.977 µg/g within a day after foliar spray. Fipronil sulphide and fipronil desulfinyl were the major metabolites on sugarcane crop. The residues (both parent compound and total residues) reached below the detectable level of 0.005 µg/g on 7 and 15 days after treatment on stem and leaves, respectively. Half-life of fipronil was less than a day on sugarcane crop. The total residues had the half-life of 1.66 and 0.91 days on leaves and stem, respectively.