Study On The Novel Sample Preparation Methods For The Determination Of Chinese Herbs And Environmental Samples

In analytical chemistry, sample preparation is one of the most frequently asked questions. Along with the increasing of a variety of industry testing standard requirements, sample detection tends to be trace-based, which requires analytical methods and instruments with high sensitivity, low detection limit and reliable accuracy. At present, in the face of the request of ng/mL or pg/mL magnitude analysis of complex samples, the problem directly points to the sample extraction and enrichment technology. Conventional extraction methods usually use large amounts of toxic organic solvents and need tedious procedures for the preconcentration of the analytes. Therefore, simple, efficient, rapid and organic solvent-free sample preparation methods are required. In this paper, novel sample preparation techniques for Chinese Herbs and environmental samples have been studied, including microwave assisted micellar extraction technique for Chinese herbal medicine salvia Miltiorrhiza bunge and dispersed phase liquid-liquid microextraction technique for environmental estrogens. In the meantime, the influencing factors and the optimum conditions were discussed respectively. This thesis consists of three chapters:Chapter one:In this part, about 90 references were cited to summarize the theory and the applications of the commonly used sample preparation techniques, special emphasis was placed on the cloud point extraction and dispersed phase liquid-liquid microextraction involving fundamental theory, experimental condition optimization and practical applications.Chapter two:nonionic surfactant, oligoethylene glycol monoalkyl ether (Genapol X-080) and microwave assist extraction were employed for the determination of Cryptotanshinone, Tanshinone I and Tanshinone IIA in Salvia Miltiorrhiza bunge prior to HPLC analysis. During the experiment, various influencing factors on the extraction efficiency were studied, such as the effects of the concentration of surfactant, granularity of the plant powder, microwave time, liquid/solid ratio, microwave power. Compared with conventional extraction techniques, the proposed method (MAME) owns higher extraction efficiency and requires less extraction timeChapter three:Two kinds of environmental estrogens (BPA/DES) were extracted and preconcentrated from water samples by using dispersed phase liquid-liquid microextraction prior to HPLC analysis. The influencing factors in dispersed phase liquid-liquid microextraction technology were studied and the experimental conditions were optimized at the same time.Water sample was detected by using the established method.