[Study on quality evaluation of Dihuang (Rehmannia glutinosa) by two-dimension HPLC fingerprints and chemometrics methods]

The study is to establish the two-dimension HPLC fingerprints of Dihuang (Rehmannia glutinosa), by HPLC-PDA and HPLC-ELSD methods. The separations were performed on Waters Atlantis®T3（4.6 mm× 250 mm，5 μm）and Welch Ultimate®Hilic-NH₂（4.6 mm× 250 mm，5 μm）columns with the gradient elution of acetonitrile-0.01% phosphoric acid and acetonitrile-water, respectively. The chromatographic display wavelength for PDA detector was set at 203 nm. For HPLC-ELSD, the nebulizer was set as cooling mode, the drift tube temperature was set at 60 °C and the gas pressure was 35.0 psi. Based on similarity evaluation system for chromatographic fingerprint of traditional Chinese medicine, 26 and 10 chromatographic peaks were determined as common components for HPLC-PDA and HPLC-ELSD fingerprints, respectively. Chemometrics analyses, such as similarity analysis; cluster analysis and principal component analysis, were performed on the common peak areas in two-dimension fingerprints for 41 batches of Dihuang from multiple sources. The results showed that the HPLC-PDA fingerprint could distinguish dried rehmannia root between different sources, and HPLC-ELSD fingerprint could differentiate dried rehmannia root from prepared rehmannia root. The two-dimension fingerprints were established with advantages of a good degree of separation, abundant chemical information and multi-components identified including two nucleosides (adenosine and uridine)，four iridoid glycosides (catalpa alcohol，rehmaionoside D，rehmaionoside A and leonuride)，two phenylethanoid glycosides (acteoside and cistanoside A) and nine sugars. The method is simple and practical, which could be used for the identification and quality assessment for Dihuang.