title: Rapid determination of N,N-diethyl-m-toluamide and permethrin in human plasma by gas chromatography-mass spectrometry and pyridostigmine bromide by high-performance liquid chromatography.
abstract: A rapid and highly sensitive gas chromatography-mass spectrometry (GC-MS) method for simultaneous determination of N,N-diethyl-m-toluamide (DEET) and permethrin with (2)H(10)-phenanthrene (98 atom %) as an internal standard and a separate external standard high-performance liquid chromatography (HPLC) method for pyridostigmine bromide (PB) determination in human plasma were developed and validated. The GC-MS method for DEET and permethrin quantification utilizes a one-step extraction with tert-butylmethylether. The HPLC method for PB quantification involves a solid-phase extraction and UV detection. The range of the analytical method for DEET and permethrin was 1 ng/mL to 100 ng/mL and for PB was 5 ng/mL to 100 ng/mL. Recovery from plasma proved to be more than 80%. The intraday precision ranged from 1.3% to 8% for DEET, from 2.1% to 11.4% for permethrin, and from 3.0% to 4.8% for PB. The interday precision was 3% for DEET, ranged from 5% to 9% for permethrin, and from 5% to 9% for PB. The accuracy for the limit of quantification was 92% +/- 8% relative standard deviation (RSD) for DEET, 112% +/- 11% RSD for permethrin, and 109% +/- 5% RSD for PB. All 3 compounds were stable in human plasma at -80 degrees C for at least 12 months and after 2 freeze-thaw cycles with RSD values ranging from 7.1% (DEET, 80 ng/mL) to 8.1% (DEET, 8 ng/mL), from 2.3% (permethrin, 80 ng/mL) to 11.6 % (permethrin, 8 ng/mL), and from 0.2% (PB, 80 ng/mL) to 3.6% (PB, 8 ng/mL). Both methods were successfully applied to pharmacokinetic/ pharmacodynamic studies of combined exposure of DEET (skin application), permethrin (treated uniforms), and PB (30 mg orally three times/day for four doses) in healthy volunteers (n = 81).
authors.affiliation: Division of Clinical Pharmacology and Medical Toxicology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Cherstniakova
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Garcia
authors.forename: John
authors.initials: J
authors.lastname: Strong
authors.forename: Daoqin
authors.initials: D
authors.lastname: Bi
authors.forename: Julie
authors.initials: J
authors.lastname: Weitz
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Roy
authors.forename: Louis R
authors.initials: LR
authors.lastname: Cantilena
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003671:DEET / Q000097:blood* / Q000493:pharmacokinetics; D004355:Drug Stability; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D007302:Insect Repellents / Q000097:blood* / Q000493:pharmacokinetics; D007306:Insecticides / Q000097:blood* / Q000493:pharmacokinetics; D008887:Military Medicine; D026023:Permethrin / Q000097:blood* / Q000493:pharmacokinetics; D011729:Pyridostigmine Bromide / Q000097:blood* / Q000493:pharmacokinetics; D015203:Reproducibility of Results
chemical_list: D007302:Insect Repellents; D007306:Insecticides; D003671:DEET; D026023:Permethrin; D011729:Pyridostigmine Bromide