Determination of tiopronin in human plasma by HPLC-MS with precolumn derivatization.

AIM:To develop a high pressure liquid chromatography-mass spectrometry method for deter- mination of tiopronin concentration in human plasma.METHODS:Chromatographic column was Waters Sun- Fire~(TM)C_(18)(2.1mm×20 mm,5μm).The mobile phase consisted of methanol -0.05% acetic acid(50:50,V/V) with a flow rate of 0.3 mL·min~(-1).MS detection in single ion monitoring mode(SIM)using electrospray ionization (ESI)as an interface was applied to determine negative ions at m/z 327.95 for TP-DNCB and m/z 253.00 for in- ternal standard(IS,daidzein).RESULTS:High specificity and a low quatitation limit(0.1 mg·L~(-1))were achie- ved.Linearity was confirmed in the concentration range of 0.1-4.0 mg·L~(-1)with the correlation coefficient(r= 0.9962).The RSD values of intra-day and inter-day assay were less than 9.4%,The extraction recovery rate of tiopronin was more than(66±s 5)%.CONCLUSION:HPLC-MS method is specific and applicable to the de- termination of tiopronin in human plasma.