Simultaneous determination of tegafur and gimeracil in human plasma by liquid chromatography/tandem mass spectrometry.

We developed a rapid, simple and sensitive LC/MS/MS method for the simultaneous quantitation of tegafur (FT) and gimeracil (CDHP) in human plasma with a concentration range of 20-5000 and 2-500 ng/mL, respectively. Methanol was chosen as a precipitation agent for sample preparation. Chromatographic separation was performed on an inertsil ODS-3 C18 column using 1.0% formic acid in water and methanol (80/20, v/v) at a flow rate of 0.3 mL/min. The MS detection was operated with selected reaction monitoring (SRM) in the positive-ion mode. The matrix effect ranged from -8.9 to 7.8% for all analytes. The intra- and inter-day precisions were less than 8.6 and 9.5%, and the accuracy was within +/-7.5% for all analytes, respectively. The mean recoveries were 76.5 +/- 5.2 and 78.3 +/- 5.9% for FT and CDHP, respectively. The analytes were stable under all possible conditions of storing and handling for each compound.