Chem. Pharm. Bull. 53(11) 1392—1395 (2005)

or pharmaceutical use of traditional Chinese medicine (TCM) has made it absolutely essential to carry out stringent quality control measures. So far, it is widely accepted that multiple constituents are responsible for the therapeutic effects of TCM, and to ensure its quality, therefore, it is necessary to quantitatively determine the multi-bioactive components of TCM. Over the past decades, various techniques have been applied extensively in the detection of bioactive components of TCM, among which, UV detector is by far the most commonly employed. In quality control, however, it has at least two unavoidable limitations. Firstly, some bioactive components in TCM, especially those in complicate formula, are non-chromophoric compounds and can not be determined unless pre-column or post-column derivatization is applied, which is often undesirable due to its time-consuming and lack of reproducibility and robustness. Secondly, the multi-components of TCM, in general, have rather different UV absorption properties, and it is often difficult to simultaneously determine multi-components with common UV detection at a single fixed wavelength. Evaporative light scattering detector (ELSD) has been increasingly used and seems to offer a useful alternative to conventional methods in the quality control of TCM. Unlike UV detection, ELSD allows the determination of nonchromophoric compounds without preceding derivatization, and thus shows good compatibility to the multi-components of complex analytes such as TCM. In recent years, it has been reported that HPLC/ELSD is an efficient tool for the determination of certain non-chromophoric compounds of TCM, such as saponins, terpenes, steroids and carbohydrates. These studies, however, merely focused on the determination of non-chromophoric compounds, which does not comprehensively represent the quality characteristics of TCM. Therefore, there is a need to develop ELSD into a quasi-universal detector for determining all available bioactive components of TCM in quality control of TCM. Qingkailing injection is a well-known composite formula of TCM and is commonly used in clinical practice. It comprises eight medicinal materials or extracts thereof, including Radix Isatidis, Flos Lonicerae, Fructus Gardenise, Cornu Bubal, Concha Margaritifera, Baicalinum, Acidum Cholicum, and Acidum Hyodesoxy-cholicum. It has been reported that the compounds of adenosine (ADE), geniposide (GEN), chlorogenic acid (CHA), baicalin (BAI), ursodeoxycholic acid (UCA), cholic acid (CA), and hyodeoxycholic acid (HCA) are the major bioactive components synergistically contributing to its therapeutic effects (see Fig. 1 for their chemical structures). Moreover, these compounds are commonly used as markers for six important medicinal materials of Qingkailing injection. Therefore, it is significant to simultaneously determine these compounds to ensure the efficacy, safety, and batch-to-batch uniformity of Qingkailing injection. While UV detection allows simultaneous determination of ADE, CHA, GEN and BAI with multi-wavelength monitoring technique, it is difficult to analyze UCA, CA