title: Persistence behaviour of imidacloprid and its metabolites in soil under sugarcane.
abstract: The persistence and metabolism of imidacloprid in soil under sugarcane were studied following application of imidacloprid at 20 and 80 g active ingredient (a.i.) ha(-1). Soil samples were collected at different time intervals (7, 15, 30, 45, 60 and 90 days after application), and the residues of imidacloprid and its metabolites (6-chloronicotinic acid, nitrosimine, imidacloprid-NTG, olefin, urea and 5-hydroxy) were quantified by high-performance liquid chromatography. In soil, the total imidacloprid residues were mainly constituted by the parent compound followed by 6-chloronicotinic acid, nitrosimine and imidacloprid-NTG metabolites. Maximum residues of imidacloprid and its metabolites were 4.29 and 7.81 mg kg(-1) in soil samples collected 7 days after the application of imidacloprid at 20 and 80 g a.i. ha(-1), respectively. At both doses, these residues declined to below the detectable limit in soil after 90 days of application. Olefin, urea and 5-hydroxy metabolites were not detected in soil. Dissipation of total imidacloprid residues did not follow the first-order kinetics with a coefficient of determination value of 0.883 and 0.838 for the recommended dose and four times the recommended dose, respectively. The half-life (T(1/2)) value of total imidacloprid was observed to be 10.64 and 10.10 days for the recommended dose and four times the recommended dose, respectively.
authors.affiliation: Pesticide Residue Analysis Laboratory, Department of Entomology, Punjab Agricultural University, Ludhiana, Punjab, 141004, India, smritisharma80@pau.edu.
authors.forename: Smriti
authors.initials: S
authors.lastname: Sharma
authors.forename: Balwinder
authors.initials: B
authors.lastname: Singh
mesh_terms: D004784:Environmental Monitoring; D006207:Half-Life; D007093:Imidazoles / Q000032:analysis*; D007306:Insecticides / Q000032:analysis*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis; D031786:Saccharum / Q000502:physiology*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010573:Pesticide Residues; D012987:Soil; D012989:Soil Pollutants; C082359:imidacloprid