title: Development of a simple extraction and oxidation procedure for the residue analysis of imidacloprid and its metabolites in lettuce using gas chromatography.
abstract: Simple extraction and optimised oxidation procedures were developed for the determination of the total residues of imidacloprid and its metabolites (containing the 6-chloropicolyl moiety) in lettuce using a gas chromatography-micro electron capture detector (GC-μECD). Samples were extracted with acetonitrile, and the extract was then evaporated. The remaining residues were dissolved in water and oxidised with potassium permanganate to yield 6-chloronicotinic acid (6-CAN). The acid residues were further dissolved in n-hexane:acetone (8:2, v/v) and then silylated with MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide) to 6-chloronicotinic acid trimethylsilyl ester. Calibration curves were linear over the concentration ranges (0.025-5 μg mL(-1)) with a determination coefficient (r(2)) of 0.991. The limits of detection and quantification were 0.015 and 0.05 mg kg(-1), respectively. Recoveries at two fortification levels ranged between 72.8% and 108.3% with relative standard deviation (RSD) lower than 8%. The method was effective, and sensitive enough to determine the total residues of imidacloprid and its metabolites in field-incurred lettuce samples. The identity of the analyte was confirmed using gas chromatography-tandem mass spectrometry (GC-MS/MS).
authors.affiliation: Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonna National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Ah-Young
authors.initials: AY
authors.lastname: Ko
authors.forename: Md Musfiqur
authors.initials: MM
authors.lastname: Rahman
authors.forename: A M
authors.initials: AM
authors.lastname: Abd El-Aty
authors.forename: Jin
authors.initials: J
authors.lastname: Jang
authors.forename: Jong-Hyouk
authors.initials: JH
authors.lastname: Park
authors.forename: Soon-Kil
authors.initials: SK
authors.lastname: Cho
authors.forename: Jae-Han
authors.initials: JH
authors.lastname: Shim
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D007093:Imidazoles / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D018545:Lactuca / Q000737:chemistry*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D010084:Oxidation-Reduction; D010573:Pesticide Residues / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D007093:Imidazoles; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010573:Pesticide Residues; C082359:imidacloprid
keywords: 6-Chloropicolyl moiety; GC-μECD; Imidacloprid; Metabolites; Oxidation