Rapid analysis of docetaxel in human plasma by tandem mass spectrometry with on-line sample extraction

A simple, rapid, and sensitive analytical method for the measurement of docetaxel in human plasma was developed and validated. The method is based on positive electrospray ionization tandem mass spectrometry (ESI+-MS-MS) with on-line sample extraction. It uses paclitaxel as internal standard for calibration. The on-line sample extraction minimizes sample handling and is readily adopted for automation. Quantitation of plasma docetaxel was done by the multiple reaction monitoring (MRM) mode. The method had a linear calibration range of 1.00-3000 ng/mL with a correlation coefficient >0.9999. The limit of quantitation (LOQ) for docetaxel in plasma was 1.00 ng/mL. The on-line extraction recovery of docetaxel was between 86.1-94.7%, with %CV < or = 6.1%. This method has high accuracy (90.1-96.3%), and excellent intra-assay (0.6-3.8%) and inter-assay (2.0-5.7%) precision. Its applicability to clinical samples was demonstrated by measuring patient plasma samples after treatment of weekly docetaxel at 25 mg/m2 as 60-min infusion.