RP-HPLC determination of linarin in beagle dog plasma after administration of Yejuhua injection

A sensitive, simple, and accurate reversed-phase column liquid chromatographic (RP-LC) method with daidzein as an internal standard and UV detection at 348 nm has been developed for determination of linarin in beagle dog plasma. Plasma protein was precipitated by addition of acetonitrile and the remaining solution was evaporated to dryness. The resulting residue was then reconstituted in methanol and injected on to a 250 mm x 4.6 mm i.d., 5 μm particle, ODS analytical column. The mobile phase was a gradient prepared from acetonitrile and an aqueous solution (0.4%) of phosphoric acid; the flow rate was 1.0 mL min^-1. Response was a linear function of concentration over the range 3.4-1,373.3 ng mL^-1; the correlation coefficient (R²) was 0.993. Mean recovery was 74.2%. Within-day and between-day precision were better than 8.8% relative standard deviation (RSD). The limit of quantification was 3.4 ng mL^-1. This RP-LC method was used successfully in pharmacokinetic studies of linarin in beagle plasma after administration of Yejuhua injection.