DETERMINATION OF ISOCORYNOXEINE IN RAT PLASMA BY LIQUID CHROMATOGRAPHY MASS SPECTROMETRY AND ITS APPLICATION

A sensitive and selective liquid chromatography mass spectrometry (LC–MS) method for determination of isocorynoxeine in rat plasma was developed. After addition of midazolam as internal standard (IS), sample preparation was performed by using liquid–liquid extraction with ethyl acetate. Chromatographic separation was achieved on a Zorbax SB-C18 (2.1 mm × 150 mm, 5 µm) column with acetonitrile-0.1% formic acid as mobile phase with gradient elution. Electrospray ionization (ESI) source was applied and operated in positive ion mode; selective ion monitoring (SIM) mode was used to quantify using target fragment ions m/z 383 for isocorynoxeine and m/z 326 for the IS. Calibration plots were linear over the range of 5–500 ng/mL for isocorynoxeine in plasma. Lower limit of quantification (LLOQ) for isocorynoxeine was 5 ng/mL. Mean recovery of isocorynoxeine from plasma was in the range of 93.6–96.6%. CV of intra-day and inter-day precision were both less than 15%. The newly developed method is simple, sensitive, ...