| Because of matrix composition being considerable complex in the food or pharmaceuticals, the content of organic compounds being usually trace, before determination the samples must be pretreatment. Solid phase extraction and liquid extraction have been broadly applied to sample preparation process. Being complicated operation, long extraction time, uneconomic, they were limited because capacity of this extraction was not strong enough for plenty of samples pretreatment, and maybe cause secondary pollution for environment and so on. Therefore, it is necessary to establish a rapid, environment-friendly, cheap, efficient, automated sample pretreatment technique to meet the needs of society and people. In this thesis, a kind of novel magnetic nanomaterials with ionic liquids as environment-friendly adsorbent was prepared. Fluorescent spectrophotometer, and spectrophotometer coupled with high-performance liquid chromatography（HPLC） were used to off-line and on-line quantitative enrichment and determination of synthetic colorants such as safranin-T in food samples, and carvedilol in pharmaceuticals. The following is the main content of this thesis.1. The recent development and applications of ionicliquid-based dispersive liquid-liquid microextraction were briefly introduced. Simultaneously, the principle of magnetic solid phase extraction, the surface modification of magnetic nanomaterials and the application field were briefly summarized. At last, the significance, purpose and content of this thesis were introduced.2. A new two-step microextraction approach has beenestablished for the determination of safranin T in food samples by fluorescence. In the first step, ionic liquid（1-hexyl-3-methylimidazolium hexafluorophosphate） was used to extract safranin T from the sample solution under the assistance of controlled temperature conditions. In the second step, Fe3O4@SiO2 magnetic nanoparticles were used to retrieve the ionic liquid and then collected by an external magnetic field. The ionic liquid and safranin T were recovered from the surface of magnetic nanoparticles by assistance of ultrasound with organic solvent, respectively. The effective parameters, including type and volume of extraction solvent, p H, dispersive temperature, extraction time, type of desorption solvent, amount of Fe3O4@SiO2 magnetic nanoparticles, and ultrasound time, were investigated in the proposed method. Under the optimal conditions, this method possessed good linearity in the range of 5 to 300 ng m L–1, with a detection limit of 0.48 ng m L–1, and good recovery rates（96.71–98.26%）. The method was successfully applied to the detection of safranin T in tomatoes, tomato sauce, and yuba samples.3. This part put forward a two-step microextraction method that was applied to extract carvedilol, an anti-arrhythmic drug, which was then quantified with fluorometry. At first, ionic liquid（1-octyl-3-methylimidazolium hexafluorophosphate） was used to extract the carvedilol. In the subsequent procedure, magnetite nanoparticles were added to the ionic liquid to absorb the carvedilol. Finally, the loaded drug-magnetite nanoparticles were collected under a magnetic field. The ionic liquid and carvedilol were recovered from the surface of the magnetite nanoparticles by ultrasonication with ethanol. Under optimum conditions, the method displayed good linearity（R2 = 0.9994） within the concentration range of 0.4 ng m L–1 to 80 ng m L–1 with a detection limit of 0.1 ng m L–1. The relative standard deviation for contained 25 ng m L–1 of carvedilol was 1.57%（n = 5）. The method successfully determined the carvedilol in tablets, human plasma, and urine, and the recoveries varied between 95.04% and 106.6%.4. A new automated magnetic solid-phase extraction（MSPE） method was developed and HPLC coupled with spectrophotometry for off-line and on-line quantitative enrichment and determination of synthetic colorants in food samples. Fe3O4-poly（ionic liquid） core-shell microspheres were prepared as a sorbent to quickly extract analytes from aqueous samples. The entire MSPE process, including extraction, separation, elution and clean, was automated throughout the process by using common equipment. The main parameters such as absorbent, sample p H, eluent, flow rate, elution time, etc., which affect the performance of MSPE and the automated process, were investigated in detail. Under the optimum experimental conditions, the limit of detection ranged between 4.1 and 14 ng m L-1 by off-line HPLC and the limit of determination of amaranth was 220 ng m L-1 by on-line spectrophotometry, with excellent reproducibility（intra- and inter-day relative standard deviations were less than 3.2%）. The developed method was successfully applied to the determination of colorants in food samples. |
