Extraction Of Drugs By Phase Separation Between Acetonitnile-Water Caused In Low Temperature

Safety and quality control of drugs has been an important research subject for scientists. With rapid development of the modern analytical techniques, the quality standards of drugs are constantly improving. Quality of drugs was based on their appearances in the past, but now is mainly dependent on the determination of chemical components and comparison with authentic plant drugs. In analytical chemistry, sample preparation is a pivotal process. Liquid-liquid extraction (LLE) is the classical method for sample preparation. The contents of traditional Chinese medicine by HPLC were studied in this thesis. The dissertation has 3 chapters and the main contents are as following:Chapter one: This chapter introduced the methods for the sample pre-treatment, for example liquid-liquid extraction (LLE), liquid phase micro-extraction (LPME), solid phase extraction (SPE), solid phase micro-extraction(SPME), cloud-point extraction (CPE), supercritical fluid extraction (SFE), ultrasonic extraction, microwave assisted extraction (MAE).The physical and chemical properties of acetonitrile and the method of subzero-temperature liquid-liquid extraction were introduced.Chapter two: For high-performance liquid chromatography of anthraquinones (aloeemodin, rhein, emodin, chrysophanol and physcion), subzero-temperature extraction technique using hydrophilic acetonitrile as a solvent was applied to the extraction of anthraquinones such as aloeemodin; rhein; emodin; chrysophanol; physcion. After the factors influencing extraction were investigated, the optimal extraction conditions were determined as follows: 3.5mL of water, 2.0 mL of acetonitrile, pH at 2.5, 30 min of extraction time, and -30℃of extraction temperature. The recovery of the target analytes was between 83.1% ~ 109.7%. The detection limits of aloeemodin; rhein; emodin; chrysophanol; physcion were 0.48, 1.50, 1.49, 0.95 and 1.72ng/mL, respectively.Chapter three: For high-performance liquid chromatography of flavonoid compounds (baicalin, baicalein and wogonin), subzero-temperature extraction technique using hydrophilic acetonitrile as a solvent was applied to the extraction of flavonoid compounds such as baicalin, baicalein and wogonin. After the factors influencing extraction were investigated, the optimal extraction conditions were determined as follows: 3.5mL of water, 2.0 mL of acetonitrile, pH at 3.0, 30 min of extraction time, and -30℃of extraction temperature. The recovery of the target analytes is between 90.7% ~ 112.7%. The detection limits of baicalin, baicalein and wogonin are 39.5, 7.89 and 1.76ng/mL, respectively.