Studies On Extraction And Crystallization Ginkgo Flavonoids Process Of Supercritical Fluid

The active ingredients of natural products are important raw materials in pharmaceutical industry. The ginkgo flavonoid is especially the research focus in the study of Chinese traditional medicine. The separating methods of ginkgo flavonoid appeared in documents are mainly the traditional method of combining solvent digestion with resin adsorption or supercritical fluid extraction. They have many defects, such as the complicated technology, solvent pollution, low production, high demands on operating conditions and so on. Therefore, they should be improved.Selecting ginkgo flavonoid glucoside as the research object, the author combined the traditional digestion method and the advanced supercritical fluid extraction and crystallization technology to obtain high purity product. First digestion by mixture of ethanol and n-BuOH(butanol) and then supercritical CO₂ extraction and crystallization, can the purity of the raw material ginkgo flavonoid glucoside be further purified from 30% to 80%, which contained no solvent and was separated from the strong polarity substance including proanthocyanidin and tannins, and the low molecular lipid soluble substance.The theoretical analyses and experimental results showed that:1. Compared with other solvents, the mixed solvents of ethanol and n-BuOH (1:20) for ginkgo flavonoid glucoside have a higher rate of extraction and more selective.2. The optimal process parameters of digestion are as follows: proportion of different solvents: ethanol: n-BuOH = 1:20; temperature: 45 ℃ ; time: 45mins; proportion of solid and liquid: 1:10.3. The process of Supercritical CO₂ extraction and crystallization can purify ginkgo flavonoid glucoside from the purity of 44% to more than 80% in one step. According to the experiments, the optimal parameters of supercritical CO₂ extraction and crystallization are as follows:Pressure: 14MPa ; temperature:50 ℃ ; modifier:absolute ethanol ; the moderate width between boards is from 0.4 to 0.8cm; time:90mins; flow rate of CO₂:20L/min.4. The whole processing is simple and efficient. Only through two steps (first digestion by mixture of ethanol and n-BuOH and then supercritical CO₂ extraction and crystallization), can the purity of the raw material ginkgo flavonoid glucoside be further purified from 30% to 80%. Thus, it greatly reduces the process procedures and improves the production efficiency.