Development and validation of a high-performance liquid chromatography-tandem mass spectrometric method for quantification of daunorubicin in rat plasma

A high-performance liquid chromatography-tandem mass spectrometric method (LC-MS/MS) has been developed and validated for the determination of daunorubicin in K₃EDTA rat plasma. The 100 μL plasma samples were extracted by a methanol:acetone protein precipitation step in the presence of additional 50 μL of 70% (w/v) zinc sulfate, and subsequently analyzed by LC/MS/MS using positive turbo-ion spray ionization mode. The LC/MS/MS instrument was operated in the multiple-reaction-monitoring (MRM) mode. Doxorubicinol was better than doxorubicin as the internal standard because its recovery and absolute matrix effect data exactly matched with those for daunorubicin. In addition, HPLC gradient condition was optimized to thoroughly separate daunorubicin from the background interference. The validated concentration range was from 0.250 to 100 ng/mL. The true recoveries of daunorubicin and doxorubicinol were 93.2% and 93.6%, respectively. In addition, the ion-suppression data of daunorubicin and doxorubicinol were 78.2% and 78.4%, respectively. Absence of the relative matrix effect from six unique lots was confirmed. Results obtained from the GLP validation study demonstrated very good accuracy (95-105%) and precision (less than 10% CV).