Abstract
Abstract This thesis consists of two projects: (1) the determination of polyphenolics in Hawthorn by accelerated solvent extraction (ASE) and high performance liquid chromatograph- UV detection; and (2) the determination of phytoestrogens in Chinese herbal medicines and nutritious supplements by HPLC/ESI-MS. The first project involves the application of accelerated solvent extraction method to extract antioxidants, i.e., polyphenolics in Hawthorn. This technology, based on increasing the boiling point of extracting solvents, is a solvent-less method operated in a closed system. It can prevent polyphenolics form degradation by light and air during the extraction stage. The analytical benefits will facilitate the modernization and quality control of herbal medicines. In the proposed method, the limit of detection (LOD) is 0.5-7-5ng/g (d.m.), and the limit of quantitation (LOQ) is 2-25ng/g (d.m.). Extracting with 60% ethanol solution at 80℃, 100bar in three cycles (3 min each), the recovery is from 88-119%. The quantitative results indicate that the contents of polyphenolics in commercial available Hawthorn are discrepant. The relation between the amount of polyphnolics and the storage time will be discussed by multivariate techniques. The second project pertains to extract phytoestrogens in Traditional Chinese medicines (TCMs) and nutrient supplements by a simple extraction method, i.e., ultra-sonication, followed by LC/ESI-MS detection. In this method, the LOD is 0.01-0.2ng/g, and the LOQ is 0.1-0.5ng/g. the RSD of reproducibility (n=3) is 2.1-9.6%. The quantitative results reveal that Daidzein and Genistein are frequently detected in TCMs, and the main phytoestrogen in nutrient supplement is Formononetein.