title: Quantitation of dialkyl phosphate metabolites of organophosphate pesticides in human urine using GC-MS-MS with isotopic internal standards.
abstract: Human exposure to organophosphate pesticides can be estimated from the presence of urinary metabolites. An isotope-dilution gas chromatography-tandem mass spectrometry (GC-MS-MS) method was developed for quantitating the six dialkyl phosphate urinary metabolites of at least 29 organophosphate pesticides. Urine samples were spiked with stable isotope analogues of the dialkyl phosphates, evaporated using azeotropic distillation, followed by chemical derivatization of the metabolites to their respective chloropropyl phosphate esters. The chloropropyl phosphate esters were concentrated and then analyzed using GC-MS-MS. The limits of detection (LODs) of the method were in the low-to-mid picogram-per-milliliter range (parts per trillion) with coefficients of variation of less than 20%. The use of stable isotope analogues as internal standards for each of these metabolites allows for the highest degree of accuracy and precision. Additionally, the low LODs allow the use of this method in general population studies.
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bravo
authors.forename: William J
authors.initials: WJ
authors.lastname: Driskell
authors.forename: Ralph D
authors.initials: RD
authors.lastname: Whitehead
authors.forename: Larry L
authors.initials: LL
authors.lastname: Needham
authors.forename: Dana B
authors.initials: DB
authors.lastname: Barr
mesh_terms: D004781:Environmental Exposure; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007306:Insecticides / Q000652:urine*; D007554:Isotopes; D009943:Organophosphorus Compounds; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007306:Insecticides; D007554:Isotopes; D009943:Organophosphorus Compounds