title: Development of a high-performance liquid chromatographic method for the quantification of chlorpyrifos, pyridostigmine bromide, N,N-diethyl-m-toluamide and their metabolites in rat plasma and urine.
abstract: A method was developed for the separation and quantification of the insecticide chlorpyrifos (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphorothioate), its metabolites chlorpyrifos-oxon (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl] phosphate) and TCP (3,5,6-trichloro-2-pyridinol), the anti-nerve agent drug pyridostigmine bromide (PB; 3-dimethylaminocarbonyloxy-N-methyl pyridinium bromide), its metabolite N-methyl-3-hydroxypyridinium bromide, the insect repellent DEET (N,N-diethyl-m-toluamide), and its metabolites m-toluamide and m-toluic acid in rat plasma and urine. The method is based on using solid-phase extraction and high-performance liquid chromatography (HPLC) with reversed-phase C18 column, and gradient UV detection ranging between 210 and 280 nm. The compounds were separated using a gradient of 1-85% acetonitrile in water (pH 3.20) at a flow-rate ranging between 1 and 1.7 ml/min over a period of 15 min. The retention times ranged from 5.4 to 13.2 min. The limits of detection ranged between 20 and 150 ng/ml, while the limits of quantitation were between 150 and 200 ng/ml. Average percentage recovery of five spiked plasma samples was 80.2+/-7.9, 74.9+/-8.5, 81.7+/-6.9, 73.1+/-7.8, 74.3+/-8.3, 80.8+/-6.6, 81.6+/-7.3 and 81.4+/-6.5, and from urine 79.4+/-6.9, 77.8+/-8.4, 83.3+/-6.6, 72.8+/-9.0, 76.3+/-7.7, 83.4+/-7.9, 81.6+/-7.9 and 81.8+/-6.8 for chlorpyrifos, chlorpyrifos-oxon, TCP, pyridostigmine bromide, N-methyl-3-hydroxypyridinium bromide, DEET, m-toluamide and m-toluic acid, respectively. The relationship between peak areas and concentration was linear over a range between 200 and 2000 ng/ml.
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Abu-Qare
authors.forename: M B
authors.initials: MB
authors.lastname: Abou-Donia
mesh_terms: D000818:Animals; D002138:Calibration; D004390:Chlorpyrifos / Q000032:analysis* / Q000097:blood / Q000378:metabolism / Q000652:urine; D002800:Cholinesterase Inhibitors / Q000097:blood / Q000378:metabolism / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003671:DEET / Q000032:analysis* / Q000097:blood / Q000378:metabolism / Q000652:urine; D007302:Insect Repellents / Q000097:blood / Q000378:metabolism / Q000652:urine; D011729:Pyridostigmine Bromide / Q000032:analysis* / Q000097:blood / Q000378:metabolism / Q000652:urine; D051381:Rats
chemical_list: D002800:Cholinesterase Inhibitors; D007302:Insect Repellents; D003671:DEET; D004390:Chlorpyrifos; D011729:Pyridostigmine Bromide