title: Monitoring of 6-chloronicotinic acid in human urine by gas chromatography-tandem mass spectrometry as indicator of exposure to the pesticide imidacloprid.
abstract: A new analytical method for determining 6-chloronicotinic acid (6-ClNA) in human urine is proposed. 6-ClNA is the main metabolite in warm-blooded animals after exposure to the insecticide imidachloprid. 6-ClNA was extracted from human urine using solid phase extraction (SPE) with laboratory-made cartridges of Amberlite XAD-4. A clean-up step and a derivatization process were carried out prior to gas chromatography-tandem mass spectrometric (GC-MS-MS) determination. A study on the influence of pH in the extraction process revealed that it affects the analyte extraction efficiency. A working pH zone was defined between 0.8 and 2.8. Calibration curves were studied in the concentration range of 0.5-100 ng mL(-1) and showed good linearity. Limits of detection and determination of the method were 16 and 56 pg mL(-1) respectively. The mean recovery at 10 and 100 ng mL(-1) was between 97.2 and 102.1% and the repeatability was lower than 5.4% in all cases. The analysis of urine samples of five agricultural workers from Almería (Spain) did not detect the metabolite.
authors.affiliation: Department of Analytical Chemistry, University of Almería, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Uroz
authors.forename: F J
authors.initials: FJ
authors.lastname: Arrebola
authors.forename: F J
authors.initials: FJ
authors.lastname: Egea-González
authors.forename: J L
authors.initials: JL
authors.lastname: Martínez-Vidal
mesh_terms: D000383:Agriculture; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D007093:Imidazoles; D000073943:Neonicotinoids; D009539:Nicotinic Acids / Q000652:urine*; D009574:Nitro Compounds; D016273:Occupational Exposure; D010575:Pesticides
chemical_list: D007093:Imidazoles; D000073943:Neonicotinoids; D009539:Nicotinic Acids; D009574:Nitro Compounds; D010575:Pesticides; C082359:imidacloprid; C035953:6-chloronicotinic acid