An estimation of the exposure to organophosphorus pesticides through the simultaneous determination of their main metabolites in urine by liquid chromatography-tandem mass spectrometry.
A rapid method has been developed for the determination of 4-nitrophenol (PNP) (parathion and methyl-parathion metabolite) and 3-methyl-4-nitrophenol (3-Me-PNP) (fenitrothion metabolite) in human urine by coupled-column liquid chromatography combined with tandem mass spectrometry (LC-LC-MS/MS). The LC-LC-MS/MS approach allows the determination at sub-ppb level of free metabolites by injecting the urine directly into the system and the total metabolites after a simple enzymatic hydrolysis. The method has been validated, obtaining limits of detection of 0.1 and 0.2 microg/L for 4-nitrophenol and 3-methyl-4-nitrophenol, respectively. Additionally, a multi-residue LC-MS/MS method is proposed in order to evaluate the levels of other parathion and methyl parathion metabolites. This approach allows the simultaneous determination of dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP), 4-nitrophenolsulphate and 4-nitrophenolglucuronide without tedious sample treatments. The applicability of both methods is demonstrated by applying them to various urine samples from an unexposed population and a grower who applied methyl parathion. The combination of both methods allows a general overview on the presence of different metabolites (free and conjugated) and the concentration ratios between them, giving useful information on organophosphorus pesticides metabolism and excretion.
Hernández
F
F
Analytical Chemistry, Experimental Sciences Department, University Jaume I, P.O. Box 224, E-12080 Castellón, Spain. hernandf@exp.uji.es
Sancho
J V
JV
Pozo
O J
OJ
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D009943:Organophosphorus Compounds / Q000652:urine*; D010575:Pesticides / Q000652:urine*
D009943:Organophosphorus Compounds; D010575:Pesticides