Applications Of Hollow Fiber Membrane Extraction In Sample Pretreatment For Ion Chromatography

As a novel sample pretreatment technology, hollow fiber membrane extraction has the advantages of simple, low cost, matrix elimination and coupled with analytical instruments easily etc. In this work, applications of the hollow fiber membrane extraction in sample pretreatment for ion chromatography were investigated.Chapter one mainly focused on the structures, types, extraction modes and extractors of the hollow fiber membrane as well as its applications in sample pretreatment for environmental analysis, biological analysis and food analysis etc.In chapter two, an in-line hollow fiber membrane extraction coupled with ion chromatography was developed for the first time. The basic principle of extraction was discussed and the parameters controlling the extraction procedure were optimized. The determination of inorganic anions in slightly water-soluble organic solvents (ethyl acetate and n-butyl acetate) was realized by transferring the slightly water-soluble organic solvents into the aqueous solutions which were then available for analysis with ion chromatography successfully, and applications of ion chromatography were expanded.In chapter three, an electro hollow fiber membrane extractor which based on electrokinetic migration was established, and combined with ion chromatography for the first time. The determination of inorganic anions in slightly water-soluble organic solvents (ethyl acetate and n-butyl acetate) was realized, and the proposed method was fast and efficient with a simple system.In chapter four, the determination of sorbic acid and benzoic acid in soy sauces and grains halid was realized by combing the hollow fiber membrane liquid-phase microextraction with the ion chromatography. The complex matrices in soy sauces and grains halid were eliminated while the detection sensitivities of benzoic acid and sorbic acid by ion chromatography were improved dramatically as well, and the application of the hollow fiber membrane liquid-phase microextraction in sample pretreatment for ion chromatography was realized for the first time.In chapter five, the micropores of the hollow fiber membrane were filled with the new-developed nanomaterial- carbon nanotubes, and carbon nanotube immobilized hollow fiber membranes were prepared. Organic acids were extracted by combing the carbon nanotube immobilized hollow fiber membrane liquid-phase microextraction with ion chromatography for the first time, and the extraction efficiencies of the organic acids especially strong-polar organic acids were improved more.