Determination of ipriflavone in human plasma by LC‐MS and its application in a pharmacokinetic study

A sensitive liquid chromatography–mass spectrometric method was developed for the quantification of ipriflavone in human plasma. The method utilized liquid–liquid extraction of plasma with ethyl acetate. A gradient elution was performed on a Hedera ODS‐2 column (150 × 2.1 mm i.d., 5 µm), using a mobile phase consisting of 0.1% formic acid solution and methanol at a flow rate of 0.5 mL/min. The single quadrupole mass spectrometer was operated in selected‐ion monitoring mode via positive electrospray ionization interface detecting m / z 239.1 and 285.1 for ipriflavone and diazepam (the internal standard), respectively. To improve the selectivity and sensitivity, the fragment ion m / z 239.1, which was produced by in‐source collision‐induced dissociation, was chosen as the quantitative ion for ipriflavone. The method was fully validated and applied to a pharmacokinetic study of ipriflavone. After oral administration of a single 200 mg ipriflavone tablet, the C max, AUC 0–72 h , t 1/2 and T max were 6.3 ± 6.3 ng/mL, 80.0 ± 69.1 µg h/L, 23.0 ± 8.6 h and 3.4 ± 2.1 h, respectively. Copyright © 2011 John Wiley & Sons, Ltd.