Simultaneous determination of ipriflavone and its main metabolites M1 and M5 in human plasma by liquid chromatography with tandem mass spectrometry

A Liquid chromatography and tandem mass spectrometry (LC/MS/MS) method has been described for the simultaneous determination of ipriflavone and its main metabolites, 7-hydroxy-3-phenyl-chromen-4-one (M1) and 7-(4-oxo-3-phenyl-4H- chromen-7-yloxy)-propionic acid (M5) in human plasma using protein precipitation. Ipriflavone, M1, M5, and the internal standard [2-(3,4-dimethoxy-phenyl)-5,7-dihydroxy-chromen-4-one] were analyzed on XTerra C₁₈ column with the mixture of acetonitrile-ammonium formate (10 mM, pH 3.0) (53:47, v/v) as mobile phase. The analytes were determined using electrospray positive ionization mass spectrometry in the multiple reaction monitoring mode. The standard curves for ipriflavone, M1, and M5 were linear over the concentration range of 1.00-500 ng/mL. The lower limit of quantification was 1.00 ng/mL using 50 μL plasma sample. The relative error and the coefficients of variation of intra- and interday assays for ipriflavone, M1, and M5 at three quality control levels ranged from -5.6 to 1.6% and 1.0 to 4.6%, respectively.