Determination of L-753,037 in human plasma by liquid chromatography/turbo ionspray tandem mass spectrometry

A liquid chromatographyic/turbo ionspray tandem mass spectrometric (LC/MS/M S) method was developed and validated for the determination of L-753,037, a potent endothelium receptor antagonist currently under development for the treatment of cardiovascular diseases, in human plasma. L-753,037 is extrac ted from 0.5 ml of human plasma using liquid-liquid extraction and analyzed by LC/MS/MS with a turbo ionspray interface. Method validation results sho wed that this method is very sensitive, reliable, selective and reproducibl e. L-753,048, an ethoxy analogue of L-753,037, was used as the internal sta ndard. The method has a lower limit of quantitation (LOQ) of 50 pg ml(-1) w ith a linear calibration range of 0.05-50 ng ml(-1). The intra-day precisio n and accuracy (n = 5) were measured to be below 10% relative standard devi ation (RSD) and between 97.4 and 102.8% of the nominal values, respectively , for all calibration standard concentrations within the calibration curve range, The inter-day precision and accuracy (n = 3 days, 5 replicates per d ay) were measured to be below 6.5% RSD and between 99.3 and 102.0% of the n ominal values, respectively, for all quality control concentrations. The ex traction recovery tvas determined to be similar to 99% on average, The anal yte was found to be stable in plasma through three freeze-thaw cycles, for at least 4 h at ambient temperature and for up to 40 days under -20 degrees C freezer storage conditions, The analyte was also shown to be stable for at least 24 h in the reconstitution solution at room temperature and for up to 3 days as a dried extract at 4 degrees C. Additional variations in plas ma concentration of the analyte due to the use of different sources of plas ma were also evaluated. Copyright (C) 1999 John Wiley & Sons, Ltd.