Novel Ion Chromatography System For The Analysis Of Complex Matrices

In recent years, ion chromatography has been an important tool for the analysis of ion species. This method has many advantages, such as high sensitivity, good selectivity and wide applications. However, analysis of complex matrices is still a challenging task. In this work, novel ion chromatography systems were established and applied to the analysis of complex matrices.In Chapter1, the recent development of the analysis of complex matrices by ion chromatography was reviewed. The chapter focused on three parts:the sample pretreatment, stationary phase and detection methods. The matrix elimination and trace analysis were pointed out.In Chapter2, a novel column-switching ion chromatography system was established and applied to the determination of trace impurity in sulfuric salts. The trace impurity (chloride) could be concentrated in the concentrator column after the first separation. Meanwhile, the matrix (sulfate) flowed to the waste. The limit of detection was10.0μg/L. The linear range was30-100μg/L. The developed method would be a promising method for the analysis of trace chloride in high-purity reagents.In Chapter3, a novel cycling-column-switching ion chromatography system was developed for the analysis of trace nitrite in high salt matrices. This system included a pump, a single eluent, two valves and a conductivity detector. Both matrix elimination and online concentration could be achieved by this method. The target anions were eluted from the analytical columns to the concentrator column circularly. Chloride matrix was eliminated completely. The method was successfully applied to the determination of trace nitrite in the chloride matrix. It was also applied to analyze trace chlorate in chloride matrix. The results demonstrated that this system was of advantages such as high sensitivity, facile automation and simple sample pretreatment, which was a promising approach for environmental researches and chlor-alkali industry. The cycling-column-switching ion chromatography system was then developed for the analysis of low-level inorganic anions in seawater. This system included a single pump, two valves, a suppressor and three columns. Using this method, six inorganic anions were eluted from the separation column to the concentrator column circularly. The matrices flowed to the waste. The linear range was0.05-25.0mg/L. The limits of detection were in the range of2.3-23.6μg/L. The RSD values were below4%. The method was convenient and practical for the analysis of trace anions in high-salinity environmental samples.In Chapter4, a selective chromatographic method was developed for the analysis of trace level bromate in food sample and drinking water. This method was based on a poly (glycidyl methacrylate-co-ethylene dimethacrylate) monolithic column, which was prepared by in-situ polymerization and then modified with quaternary amine groups. Morphology of the stationary phases was investigated by scanning electron microscopy. Permeability and mechanical stability of the column were both good. Bromate was detected after post-column reaction with potassium iodide at352nm. The parameters affecting the detection limit were studied in detail.In Chapter5, a novel monolithic stationary phase containing multiwall carbon nanotube was prepared by in-situ polymerization of methacrylate monomers in a silanized capillary. These columns were used in the separation of five inorganic anions. Carbon nanotube played an important role in the chromatographic separation. Both the exchange capacities and column efficiencies were improved by adding carbon nanotube in the monoliths.