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 medicinal preparations containing scutellaria-coptis herb couple.

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% NaH(2)PO(4), chromatography was performed using a C(18) 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.