RESUMO
Objective To develop a method for determination of ultra-trace 2-chlorovinylarsonic acid(CVAOA)in human urine specific to lewisite exposure. Methods The conditions for dispersive liquid-phase microextraction(DLPME)were optimized by orthogonal experiments with results as follows:a mixture of 250μl methanol(dispersive solvent),250μl ethyl acetate(extraction sol?vent),and 3,4-dimercaptotoluene(DMT)(derivatization reagent,using 1∶100 mole ratio of CVAOA to DMT)was injected into 1 ml urine when pH was adjusted to 1. In the next 60 min,the CVAOA was derivated and the CVAOA-DMT derivative was extracted simul?taneously at 90℃. The derivative was then analyzed by gas chromatography/tandem mass spectrometry-select reaction monitoring〔GC/MS/MS(SRM)〕. Results The linear calibration extended from 50 pg/ml to 1μg/ml(r2=0.9999)with the relative standard deviations (RSD)less than 10%. The limit of detection was 18 pg/ml and the limit of quantitation was 56 pg/ml,which was much lower than that of the reported DLPME methods. When detecting human urine samples with low,middle and high spiked concentrations(0.5,5 and 50 ng/ml)of lewisite,the analysis accuracies ranged from 98.2%to 104%and the RSD ranged from 6.9%to 8.9%. Conclusion The method developed in this study has high specificity and sensitivity as well as good precision and accuracy. It is s imple and can be readi?ly applied to the exposed sample analysis.