| Cloud point extraction (CPE) is called environment friendly extraction technology, due to the failure of volatile organic solvents, non-toxic, higher extraction efficiency and simple. This technology is often used to separate and enrich samples which in the geology, biology and environment. CPE utilizes the phenomenon of phase separation of surfactant and when the concentration of surfactant increases to a certain value, the surfactants will form various micelles. The interested analytes can be extracted into the micelles, so that can make the more dissolving in water solution, increasing the solubility of interested analytes. It is called solubilization. At this time, surfactant aqueous was heated making the temperature of surfactants aqueous rise, surfactant solutions will become turbid and appear phenomenon of phase separation. So, the hydrophobic materials that come into the micelle and hydrophilic materials that stay in the water phase can be separated in order to realize the purpose of enrichment and separation.A dual cloud point extraction (d-CPE) is twice enrichment technology which is based on conventional cloud point extraction. In d-CPE, cloud point extraction procedure is carried out twice in the treatment of the same sample process. After the first cloud point extraction, the surfactant phase was not detected directly, but added the back-extraction solvent which can destroy the chemical bond formed between surfactant and chelates or organic compounds, and back-extraction solvent will form new hydrophilic complexes with the chelates or organic compounds. After the thermostatic bath and certification, target objects were back-extracted into aqueous phase. The aqueous phase which contains the target objects was determined by detecting instrument. This method overcomes the faults that some of the atomic emission spectrometry cannot be introduced a lot of organic solvent, also avoids the influence of the viscous surfactant on capillary electrophoresis, improves the selectivity of the analysis method.Based on the previous reports, doul cloud point extraction and cloud point extraction method were carried out to enrich metal ions in environment sampels and the form of chrome and antimony were also studied in this paper. The experiment is divided into three parts:1.8-Hydroxyquinoline(8-HQ) was used as chelating reagent reacting with metal ions, non-ion surface active agent TritonX-114was used as surfactant and HNO3was used as back-extraction reagent for destroying the chemical bond formed between TritonX-114and chelates which were formed by reaction8-HQ with Cd、Co、Ni、 Pb、Zn and Cu. And determined by the atomic emission spectrometry(ICP-OES). The effects of experimental conditions, such as, pH, the concentration of HNO3,8-HQ, TritonX-114, the temperature and time of equilibration were discussed. Under the best optimized conditions:pH7.0,2mL0.8mol L-1back-extraction reagent HNO3,2.0×10-4mol L-18-HQ,0.05%TritonX-114, heated in a thermostated bath at55℃for25min. The detection limit were0.01,0.04,0.01,0.34,0.05and0.04μg L-1for Cd, Co, Ni, Pb, Zn and Cu respectively. The new-style method was applied to the determination Cd, Co, Ni, Pb, Zn and Cu in water samples.2. Ammonium pyrrolidinedithiocarbamate(APDC) was selected as chelating reagent reacting with Cr(Ⅲ) and Cr(VI), non-ion surface active agent TritonX-114was selected as surfactant and ethylene diamine tetraacetic acid(EDTA) as masking agent when extracting Cr(Ⅲ). At the condition of pH8.0, Cr(Ⅲ) and Cr(Ⅵ) can be extracted by APDC simultaneously. At the condition of pH3.0and EDTA as masking agent, Cr(Ⅵ) can be extracted by APDC singly. Cr(Ⅲ) and Cr(VI) were determined by the flame atomic absorption spectrometry (FAAS). The impacts of experimental conditions, such as, pH, the concentration of APDC, TritonX-114, EDTA, the temperature and time of equilibration were discussed. Under the best optimized conditions:pH8.0,0.08%APDC,0.05%TritonX-114, the preconcentrated factors of17.74and21.80, the detection limit of3.39and3.89μg L-1for Cr(Ⅵ) and total Cr, respectively. The above method was applied to determinate Cr(Ⅲ) and Cr(Ⅵ) in water samples with satisfactory results.3. Ammonium pyrrolidinedithiocarbamate(APDC) was also used as chelating reagent reacting with Sb(Ⅲ) and Sb(Ⅴ), non-ion surface active agent TritonX-114was used as surfactant. Sb(Ⅲ) was selectively extracted at pH4.0, and Sb(Ⅲ) and Sb(Ⅴ) were extracted at pH1.0without an oxidation or reduction process. Then Sb(Ⅲ) and Sb(Ⅴ) were detected by the flame atomic absorption spectrometry (FAAS). The optimum concentration of TritonX-114was0.05%for Sb(Ⅲ) and0.075%for total Sb. The optimum concentration of APDC was0.03%for both Sb(III) and total Sb, the temperature and time of equilibration were45℃,20min. Under the best optimized conditions, CPE permitted the preconcentrated factors of17.21and20.56, the detection limit of5.28and3.53μg L-1for total Sb and Sb(Ⅲ), respectively. The sensitive and selective method was applied to determinate Sb(Ⅲ) and Sb(V) in water samples with satisfactory results. |
PDF Full Text Request