Development and validation of a liquid chromatography-electrosprayionizaton mass spectrometric mehtod for the detrmination of dexamethasmone in sheep plasma

摘要

A quantitative liquid chromatographic-electrospray ionizatonmass spectric emthod for the detrmination of dexamethasone in sheep plasma has been developed and validated.The samples were extractedusing solid-phase XTerra MS C_18 column(3.0 mm X150 mm;5 mum)using a mobile phase consisting of 65% methanol in water containign 0.1%(V/v) fromic acid,pumped at a flow rate of 0.30 ml min~-1.the analyte was detected after positie electrospray ionization using selected ion monitoring (SIM) mode.the probe heatr temperature was set at 260 degC,the capillary voltage was set at 3.5 kV and the source block voltage (AQA_max) was set at 30 V.Themehtod was fully validated.Calibration graphs werelinear (r betterthan 0.998 ,n=11),in concentraton ranges 6-1000 ng ml~-1 for dexamethasone. The intra- and inter-day RSD values werelessthan 24.1%(n=6).Thelimits of detection and quantitation for dexamethasone were found to be 1 and 6 ng ml~-1,respectively. The efficiency fo the solid phase extraction procedure was foudn to be 92.4% for dexamethasone.The method was further applied to a pilot kinetic study in order to assess the main pharmacokinetic parameters of dexamethasone in sheep.