Determination of catalpol in dried rehmannia root and Taohong Siwu Decoction with high performance liquid chromatography

To determinate the catalpol contents in dried rehmannia root and Taohong Siwu Decoction containing rehmannia root with high performance liquid chromatography (HPLC).Catalpol was separated on a YWG-C18 column using water-acetonitrile (99.4:0.6) as mobile phase and detective wavelength at 210 nm.The linear curve of tested catalpol concentration within the range of 0.0536-5.3600 microg/microl was ideal (n=5, r=0.999 7). The average recovery rate of the dried rehmannia root and Taohong Siwu decoction was 98.7% (RSD=0.48%) and 98.2% (RSD=1.29%) respectively.HPLC method is accurate and valuable for the quality control of Radix Rehmanniae and Taohong Siwu Decoction.