| Extraction as a commonly used sample pre-treatment methods mainly including liquid-liquid extraction, soxhlet extraction, supercritical fluid extraction, and so on. These methods have several shortcomings such as using a lot organic solvent; time-consuming; high cost and hardly to popularize. Especially, these methods suffered from obvious restrictions in trace analysis.Cloud point extraction(CPE) is a new environmentally benign liquid-liquid extraction technology emerged in recent years, which is based on the solubility and cloud point phenomenon of non-polar surfactants. The cloud point phenomenon can be used to separate the hydrophobic and hydrophilic compounds by altering the experimental parameters(such as pH; temperature and ionic strength, etc.). Compared with the traditional extraction, CPE is an environmental friendly technology which is no use of volatile organic solvents, lower toxicity, low cost and highly efficient. After extraction, the surfactant phase can be miscible with water-soluble organic solvent, so this technology can hyphenated with HPLC, FIA and CE. It also can combine with GC after the enrichment phase were processed under ultrasound or microwave-assisted back extraction. The previous methods about the determination of benzoic acid, phthalic acid ester and nitrophenol were directly use organic solvent extraction or by solid phase micro-extraction, these methods were time-consuming and used a lot of organic solvent. In this paper, we used the environmentally benign liquid-liquid extraction(CPE) and established some new methods for the determination of samples(such as benzoic acid in milk, phthalic acid ester in serum and nitrophenol in water). This method solved the mentioned problems and achieved the aim of green analysis. This paper includes four chapters.In chapter I: Introduced the principle, influence factors, applications of CPE.In chapter II: A new CPE-HPLC method was developed for the determination of benzoic in milk. Non-ionic surfactant Tween-20 was chosen, the effect of experimental conditions was discussed to determine the optimal conditions of experimental.In chapter III: A new method was developed for the determination of DMP, DEP, DBP in serum using the CPE coupled with ultrasonic-assisted back-extraction as a prior step to GC-FID detection. Triton X-114 was chosen as extraction solvent and the results are satisfied. In chapter IV: Dual CPE using Na2B4O7-NaOH(pH9.3) as buffer and Triton X-114 as extraction solvent was developed as a preconcentration and clean-up technique for capillary electrophoresis analysis of nitrophenol. The extraction conditions such as the amount of Triton X-114, equilibration temperature, equilibration time and pH were evaluated and optimized.
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