title: Molecularly imprinted solid phase extraction of urinary diethyl thiophosphate and diethyl dithiophosphate and their analysis by gas chromatography-mass spectrometry.
abstract: An analytical method involving molecularly imprinted solid phase extraction (MISPE) and gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of organophosphates metabolites (diethyl thiophosphate--DETP and diethyl dithiophosphate - DEDTP) in human urine samples. A DETP molecularly imprinted polymer (MIP) was synthesized using 4-vinylpiridine as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The conditioning step of the MISPE was conducted by running 3 mL of acetonitrile, 3 mL of 0.1 mol L⁻¹ dibasic phosphate buffer at pH 11 and 2 mL of water through the molecularly imprinted polymer (MIP) cartridge. The extraction step was executed using 1.0 mL of a urine sample, with the pH previously adjusted to 3.0. Finally, the analytes were eluted with 3 mL of acetonitrile and derivatized with 3% 2,3,4,5,6-pentafluorobenzyl bromide solution at room temperature for 1h. The sample was analyzed by GC-MS in the SIM (selected ion monitoring) mode. Analytical calibration curves for DETP and DEDTP were constructed using a pool of urine samples and six levels of concentration. The method was found to be linear from 10 to 500 μg L⁻¹ (r>0.99) with limits of quantification of 10 μg L⁻¹ for both analytes. The within-day and between-day precisions were evaluated (as %RSD) and all the results were <15% for both analytes. The method was accurate (relative error<±15%), with good robustness.
authors.affiliation: Toxicants and Drug Analysis Laboratory-LATF, Faculty of Pharmaceutical Sciences, Federal University of Alfenas-Unifal-MG, 700 Gabriel Monteiro da Silva street, 37130-000 Alfenas, MG, Brazil.
authors.forename: Mariane Gonçalves
authors.initials: MG
authors.lastname: Santos
authors.forename: Ricardo Vilela
authors.initials: RV
authors.lastname: Vitor
authors.forename: Felipe Lopes
authors.initials: FL
authors.lastname: Andrade
authors.forename: Isarita
authors.initials: I
authors.lastname: Martins
authors.forename: Eduardo Costa
authors.initials: EC
authors.lastname: Figueiredo
mesh_terms: D000327:Adsorption; D004781:Environmental Exposure; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016014:Linear Models; D054802:Molecular Imprinting / Q000379:methods*; D010755:Organophosphates / Q000302:isolation & purification / Q000652:urine; D010575:Pesticides / Q000302:isolation & purification / Q000652:urine; D010710:Phosphates / Q000302:isolation & purification* / Q000652:urine*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010755:Organophosphates; D010575:Pesticides; D010710:Phosphates; C035638:thiophosphoric acid