Simultaneous determination of baicalin and chlorogenic acid in human plasma by UPLC-MS/MS

To develop and validate an ultra performance liquid chromatography tandem mass spectrometric (UPLC-MS/MS) method for the simultaneous quantification of baicalin and chlorogenic acid in human plasma after iv infusion of Yinhuang injection, the analytes were isolated from plasma by protein precipitation with methanol. Then they were chromatographied on an Acquity UPLC BEH C18 column (50 mm x 2.1 mm ID, 1.7 microm) at 40 degrees C. The mobile phase A consisted of water and 0.1% formic acid. The mobile phase B consisted of methanol and 0.1% formic acid. The analytes were eluted from the column with a linear gradient from 5% B to 80% B in 5 min, then hold for 0.5 min before returning to initial condition. The flow rate was 0.35 mL x min(-1). A tandem mass spectrometer equipped with electrospray ionization source was used as detector. Multiple reaction monitoring (MRM) using the precursor to product ion pairs of m/z 447-->271 (for baicalin), m/z 353-->191 (for chlorogenic acid) and m/z 287-->287 (for internal stand