[End point determination by HPLC chromatographic fingerprint in processing prepared Rehmannia]

To establish HPLC chromatographic fingerprints to control the quality of Chinese herbal medicine. In this study, fingerprints were established based on HPLC-DAD chromatographs. And with these fingerprints, content variations of three important active components catalpol, 5-hydroxymethylfurfural and acteoside in Rehmannia rhizome were analyzed during processing, as well as changes of the fingerprints. Fingerprints comparing with the standard prepared Rehmannia fingerprints which came from the mean of prepared ones randomly chosen for standard was done to seek optimal processing time. The results indicated that catalpol decreased quickly as braising prolonged and almost vanished in the end. While the active component of 5-HMF increased linearly throughout the process of braising. And the content of acteoside did not show obvious change. Similarity to standard prepared Rehmannia reached summit after braising for 26 hours. So 26 hours could be considered to be the optimum time for braising prepared Rehmannia. Chromatographic fingerprint is convenient for revealing changes of constituents and for accurately controlling quality during processing prepared Rahmannia.