Study On Mixed Hemimicelles Magnetic Solid Phase Extraction And Dispersive Micro-solid Phase Extraction

As an important sample preparation method, solid phase extraction has been widely used for extraction, clean-up and pre-concentration of compounds from biological, food and environmental samples. Nowadays, the trend of solid phase extraction based on miniaturization has led to the development of different miniaturized solid phase extraction techniques, which require less labor and time and reduce the amounts of solvents used in the process. In this paper, two miniaturized solid phase extraction methods were studied. This thesis is divided into three chapters, the contents are as follows:Chapter 1: Current state and trend of solid phase extraction were summarized. Special emphasis was placed on solid phase microextraction, magnetic solid phase extraction and dispersive micro-solid phase. At the same time, the main idea of the study was elaborated.Chapter 2: A method for determination of four synthetic estrogens in drinking water by mixed hemimicelles magnetic solid phase extraction-HPLC/UV was established. Fe3O4 nanoparticles were prepared by solvothermal reaction, and characterized by Fourier transform infrared spectroscopy. The effects of the amount of CTAB, p H value, amount of Fe3O4, type of eluent solvent and sample volume were evaluated and optimized. Under optimum conditions, i.e. 20 mg CTAB, p H 11, 100 mg Fe3O4, 3 m L 1% HAc-CAN and 300 m L sample,the extraction recoveries reached the highest value. Bisphenol A, diethylstilbestrol,octylphenol and nonylphenol showed excellent linearity(R2>0.9996), with limits of detection ranging between 0.011 and 0.037 ?g/m L. Under optimized conditions, the method was applied to the determination of four synthetic estrogens in two kinds of drinking water samples with satisfactory recoveries(75.8%-106.0%). Relative standard deviations for intraand inter-day precision were less than 4.31% and 5.70%. The outstanding features of the method combine the advantages of mixed hemimicelles and Fe3O4 nanoparticles. Magnetic separation simplifies the separation, and the use of CTAB as extraction medium reduces the consumption of organic solvents,which is environmentally friendly.Chapter 3: A novel dispersive micro-solid phase extraction method based on chitosan-assisted in-syringe extraction for determination of anthraquinones in three kinds ofrhubarb oral liquids was established. Some parameters affecting the extraction recovery,including the concentration and molecular weight of chitosan, extraction time, p H of the solution, type and volume of eluent were evaluated. Under optimum conditions, i.e. 0.6?g/m L chitosan, Mr 3000, 2 min, p H 5.0 and 800 ?L methanol, the extraction yield reached the highest value. Under optimized conditions, good linearity was obtained for the three anthraquinones in the range of 5-100 ng/m L(R2>0.998). The limit of detection was in the range of 1.8-3.0 ng/m L, relative standard deviations for intra- and inter-day precision were less than 4.68% and 5.36%. The method was successfully applied to determine the content of three anthraquinones in Huangzhihua oral liquid, Children's heat-clearing oral liquid and Magnolia exhaust mixture, and the contents of emodin, chrysophanol, physcion in the three kinds of rhubarb oral liquids are in the range of 28.4-64.3 ng/m L, 42.7-57.0 ng/m L and8.1-10.7 ng/m L, respectively. Satisfactory extraction recoveries for the three anthraquinones were in the range of 85.9%-120.3%. This study is the first use of chitosan as a sorbent material in dispersive micro-solid phase extraction, which combined with HPLC/UV to analyze anthraquinones in rhubarb oral liquids.