An LC–MS/MS method for the simultaneous determination of chlorogenic acid, forsythiaside A and baicalin in rat plasma and its application to pharmacokinetic study of Shuang-huang-lian in rats

An LC–MS/MS method was developed for the simultaneous determination of chlorogenic acid, forsythiaside A and baicalin, three major ingredients in Shuang-huang-lian preparations, in rat plasma. Following extraction by methanol–ethyl acetate–trifluoroacetic acid (49:49:2, v/v/v), the extracted analytes were separated on a reverse phase C12 column using a gradient mobile phase system of acetonitrile–water containing 0.1% formic acid. The limits of quantification were between 1.0 and 2.1 ng/mL, the precision was <7% and the accuracy was between 94% and 107%. The validated method was applied to a comparative pharmacokinetic study in rats after administration of Shuang-huang-lian solutions via intravenous, peroral or intratracheal routes. The results showed that the three chemical markers were more rapidly and thoroughly absorbed following pulmonary delivery as compared with peroral administration.