Determination of intact oxaliplatin in human plasma using high performance liquid chromatography-tandem mass spectrometry

A HPLC-tandem mass spectrometry method was developed and validated for the quantitation of intact oxaliplatin in human plasma. Plasma ultrafiltrates were precipitated with acetonitrile and separation was performed on a 250 mm Beckman ODS reverse phase column using a gradient mobile phase. The mass spectrometer was operated in positive ionization mode using TurboionSpray and precursor–product ion combinations of m/z 391.1 → 305.1 and 371.1 → 247.0 were monitored for oxaliplatin and carboplatin, the internal standard, respectively. The lower limit of quantitation for oxaliplatin was 20 ng/ml. The linear range of the method was 20–1000 ng/ml. The between- and within-day relative standard deviations ranged from 3.1 to 7.7%, and accuracy was within 5%. This method was successfully applied in a clinical study of oxaliplatin.