Simultaneous determination of baicalin, baicalein, wogonin, berberine, palmatine and jatrorrhizine in rat plasma by liquid chromatography–tandem mass spectrometry and application in pharmacokinetic studies after oral administration of traditional Chinese

A sensitive, rapid and selective liquid chromatography–tandem mass spectrometry (LC–MS–MS) method was developed and validated for the simultaneous determination of baicalin, baicalein, wogonin, berberine, palmatine and jatrorrhizine in scutellaria–coptis herb couple in rat plasma. After protein precipitation with acetonitrile and 0.1% NaH2PO4, chromatography was performed using a C18 column, with gradient elution with 0.1% formic acid and acetonitrile at 0.25 ml/min. All analytes including internal standards were monitored under positive ionization conditions by selected reaction monitoring with an electrospray ionization source. The lower limit of quantification was 10 ng/ml for baicalin, baicalein and wogonin, and 0.6 ng/ml for berberine, palmatine and jatrorrhizine. The validated method was applied in pharmacokinetic studies after oral administration of Yiqing Capsule and Gegen-Qinlian Tablet to rats.