Determination of eprosartan in human plasma and urine by LC/MS/MS

A protein precipitation, liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of eprosartan in human plasma and urine. The solvent system also served as a protein precipitation reagent. The chromatographic separation was achieved on a CAPCELL PAK C18 column (50 mmx2.0 mm, 5 microm, Shiseido). A mobile phase was consisted of 0.5% formic acid in water and 0.5% formic acid in acetonitrile (72:28). Detection was by positive ion electrospray tandem mass spectrometry on a Sciex API3000. The standard curves, which ranged from 5 to 2000 ng/mL in human plasma and from 0.25 to 50 microg/mL in urine, were fitted to a 1/x weighted quadratic regression model. The method proved to be accurate, specific and sensitive enough to be successfully applied to a pharmacokinetic study.