Separation and identification of the organic acids in Angelicae Radix and Ligustici Rhizoma by HPLC and CE

Angelicae Radix (AR) and Ligustici Rhizoma (LR) are both derived from the Umbelliferae plants and contain similar organic acids as their bioactive compounds. Nine of these organic acids, including nicotinic acid, protocatechuic acid, phthalic acid, folinic acid, p-hydroxybenzoic acid, folic acid, vanillic acid, caffeic acid, and ferulic acid were separated by HPLC and CE. Detection at 210 rim. with a linear gradient containing 20 mM KH2PO4 (pH 3.5) and H2O - CH3CN in HPLC and with a buffer solution containing 10 mM LTAC, 2 mM Na2HPO4, 9 mM Na2B4O7 (pH 9.56), and CH3CN in CE were found to be the most efficient eluents for this separation. The contents of the nine components in crude extracts of either AR or LR could easily be determined within 60 min by LC and within 20 min by CE. The structures of the individual peaks in the LC chromatogram were identified by LC-MS. The effects of buffers on the separation and validation of the two methods were examined.