浊点萃取在原子吸收光谱分析中的应用进展

浊点萃取(Cloud Point Extraction,CPE),是基于非离子型表面活性剂溶液的浊点现象和胶束增溶效应而建立的一种萃取技术。大部分金属螯合物具有微溶于水的特性,与表面活性剂的疏水基团结合,富集于小体积的富胶束相内,亲水性物质仍留在水相中。再经两相分离,即可实现样品中的目标化合物的分离和富集。浊点萃取法的优点:避免使用对人体有害的挥发性有机溶剂,不污染环境,安全;试剂消耗少,经济;减少萃取时间,快速高效;操作比较简便;对各种分析物具有高的萃取效率,富集倍数大;易于与仪器分析方法联用等。浊点萃取是分离和富集痕量金属离子的有效方法,是一种有发展前途的环境友好的分离富集技术。

The application of cloud point extraction in atomic absorption spectrometry

Cloud point extraction(CPE)is based on cloud point phenomenon and micellar solubilization effect of non-ionic surfactants in aqueous solutions.The most nonionic surfactants form micelles in aqueous solutions and become turbid when they are heated beyond the cloud point temperature.Above this temperature,the micellar solution separates into two phases:a surfactant-rich phase of small volume and a diluted aqueous phase of large volume,in which the surfactant concentration is close to the critical micellar concentration(cmc).The most of metallic ions can form the hydrophobic chelates or complexes solubilized in the hydrophobic core of the micelles become concentrated in the surfactant-rich phase of small volume through interaction with the micellar system, whereas hydrophilic constituents still retain in the aqueous phase of large volume.Accordingly,The target analyte in the initial sample solution may be separated after the separation into two phases by centrifugation and thus also be preconcentrated.The cloud point extraction has some advantages over conventional liquid-liquid extraction.It avoids use of large volumes of volatile,toxic and flammable organic solvents and has only small environmental pollution.It greatly reduces the solvent consumption and extraction time.CPE has the high extraction efficiency and enrichment factor for various target analytes.Its procedures is fast and highly-efficient.In addition□CPE can combine with instrumental analysis methods easily.The cloud point extraction is an effective separation and preconcentration means for several trace metallic ions and a very promising‘environment friendly’technique of separation and preconcentraction.