Determination of divalent carboxylic acids in traditional Chinese herbal and patent medicines using HPLC with double cell quartz crystal detector

A rapid, simple and sensitive high performance liquid chromatography (HPLC) method combined with a novel double cell quartz crystal (DCQC) detector is described for the determination of divalent carboxylic acids in traditional Chinese herbal and patent medicines. The chromatographic system involves the use of a muBondapak-NH2 column with 20 mM KH2PO4 (pH 3.4, adjusted by H3PO4)/acetonitrile (95:5%) as a mobile phase. The DCQC detector has a low temperature coefficient and high conductance sensitivity independent of the background from 7.2 to 2500 microS. Analysis of sample is completed without the use of an ion suppression device.