Simultaneous determination of seven metabolites of organophosphate esters and 8-hydroxy-2′-deoxyguanosine in urine by high-performance liquid chromatography-tandem mass spectrometry with homemade mixed column purification

A method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) with a small homemade mixed column was developed for the simultaneous determination of seven metabolites of organophosphate esters (OPEs) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), an DNA oxidative damage marker, in urine. The urine samples were extracted by acetonitrile and enriched by the self-made column. All the samples were separated by gradient elution with acetonitrile-0.2% (v/v) ammonia solution, and then analyzed by an electrospray ionization source in negative ion multiple reaction monitoring mode. The results showed that the eight targets had good linearities in the range of 0.1-200 mu g/L. The recoveries of the seven metabolites of OPEs and 8-OHdG in urine samples were in the ranges of 52.36% to 114.56% and 88.63% to 97.72%, respectively. The established method was successfully applied for the determination of the abovementioned eight target compounds in real urine samples, with the mass concentrations of the seven metabolites of OPEs and 8-OHdG being 6.24-46.07 mu g/L and 5.90-16.71 mu g/L, respectively. In addition, significant correlations were found between 8-OHdG and the total content of the seven metabolites of OPEs. The established method is simple, sensitive, accurate, and reproducible, and it provides reliable technical support for a more comprehensive evaluation of the level of human exposure to OPEs and the resulting health hazards.