Development Of Online Preparation And Post-column Derivetization Methods For Ion Chromatography

Ion chromatography(IC), since1970s, first introduced by H. Small, has been one of the most effective tools for the analysis of different ions. Nowadays, it has been widely used in the fields of purity tests of chemicals, environmental monitoring, energy industry, pharmaceuticals industry and bioscience. With its fast developing, IC faces the challenge of samples and target ions being more and more complex. The need exists to optimize the methods of sample pretreatment and use a variety of detectors to increase its sensitivity. In this thesis, the system of online preparation and post-column derivetization for ion chromatography was set up. And application of the system to analyze aions in complex matrix has been described.Firstly, the developments, classifications and main applications of IC have been introduced. By describing the progress of the pretreatment and post-column derivetization methods, we made a conclusion of the advantages and disadvantages for those methods.Secondly, the system of online preparation was set up, which has been applied to the analysis of Cr(III) and Cr(VI) in leathers and glyphosate in genetically modified soybean oil. In this work, the organic matrix was removed by using a reverse-phase column as the pretreatment column. After injection, the ions moved out of the pretreatment column were received by a collection loop. Then the ions were delivered into the analytical column and separated and detected by their detectors. Results showed that this method had the advantages of fewer steps for pretreatment, faster detection and being more automatic and efficient.Thirdly, a new analytical method using ion exchange chromatography post-column derivatisation UV-VIS detector has been developed and validated for the simultaneous determination of silicate and phosphate. Spectrophotometric detection was performed at805nm for molybdenum-blue by adding molybdate and ascorbic acid as the color-forming reactants. This method successfully eliminated F" interference in the formation of molybdenum-blue. The experimental results showed that there was good linearity, reproducibility and selectivity.At last, a simple method based on IC with conductivity detection was developed for the determination of iminodiacetic acid (IDA) in the herbicide of glyphosate. Under optimized chromatographic conditions, good linear relationship, sensitivity and reproducibility were obtained. It was the first time that analysis of IDA in glyphosate was described systematically in the world.