Determination of the docetaxel vehicle, polysorbate 80, in patient samples by liquid chromatography-tandem mass spectrometry.

A new simple method was developed for the quantitative determination of the docetaxel (Taxotere) vehicle, polysorbate 80 (Tween 80), in human plasma. Calibration curves were constructed in the range of 1-100 microg/ml, using paclitaxel (0.01 mM) as internal standard, and were analyzed using a power fit with equal weighting. Sample pretreatment involved a one-step extraction with acetonitrile-n-butyl chloride (1:4, v/v). The analytes were separated on a Waters X-Terra MS column (50x2.1 mm I.D.) packed with 3.5-microm ODS material, and eluted with methanol-water (9:1, v/v) containing 0.1% formic acid. The column effluent was monitored by tandem mass spectrometry with electrospray ionization. The overall extraction efficiency was 50-60%, with values for precision and accuracy of < or =16% and <15% relative error, respectively. Our current method is approximately 60-100-fold more sensitive than previous assays, and will be used to define Tween 80 disposition in patients receiving Taxotere.