High Performance Liquid Chromatography In Trace Element Speciation Analysis In Applied Research

With the development of modern science, people realize increasingly that physiological action of trace element on human body and environment is related to its existing form. Researches indicate that the different form of the element carries different poisonous characteristics and chemical features and there may be a great difference between the physical chemistry feature of the chemical compound in homologue and its physiological effect. For many samples, both composition analysis and form analysis are necessary. Consequently composition analysis of element becomes the leading task in modern environment science, physiological chemistry and biological science as well.The low content of the trace element in the sample and the great difficult in separating the different form of the chemical compounds of the same element require the analytical technique that is highly sensitive and selective. Many methods applied to conduct the researches on the form of the element have been used, but when the characteristics of the several forms in the sample are similar, the direct determination will make them interfere with each other. HPLC technology not only can do both the separating and determining work, but also can select different separating conditions to solve the knotty problem of separating chemical compounds with different form of the trace element with the help of precolumn and poslcolumn derivatization. If equipped with the different determiner, HPLC technology can separate and analyze the objects within a wider range with high sensitivity and selection, thus can play an very import part in the speciation analysis of the trace element in the complicated system and become one of the most suitable methods in speciation analysis.In this research HPLC technology is used to analyze the form of the trace element in order to explore the mew system of separating and analyzing of the chemical compound with different form of the trace element, to seek the new methods of derivation and to realize the determination of the chemical compound with the different form of the trace element simultaneously.The first chapter of the research falls into three parts. The first deals with the introduction about the basic principles, devices, classifications and applications of the HPLC. The second part summarizes the form analysis of the element in the aspect of definition, characteristics and analytical methods. The third part looks at the recent application of the form analysis and looks into the development tendency in the future.The second chapter describes the simultaneous determination of IO₃^- and I^-by using RP-HPLC. A new method of determining IO₃ ^- and I^- on ODS2 column(4.6×250mm, 5μm). Methanol-water(volumn ratio 30:70)was used as the mobile phase and tetrabutylammonium bromide(TBA·Br)as the ion-pair reagent. The detection wavelength was 218nm and the detection limits are 0.709μg/L, 0.011μg/L for IO₃^- and I^-. This method has been used to determine iodine content in sea- water and salt with iodine.The third chapter is the research on the simultaneous separation and determination of Cr (III) and Cr (VI) by using RP-HPLC. A method for the fast determination of Cr(III)-EDTA and Cr(VI) complexes has been developed. Cr(III) -EDTA and Cr(VI) complexes were separated on a Waters Spherisorb ODS2 column(4.6×250mm, 5μm) using methanol-water(10:90) including TBA·Br(5mmol/L) and 5mmol/L(pH=5.29)of phosphoric buffer solution as mobile phase at a flow rate of 1.0 mL/min and detected at 242 nm. The detection limit for Cr (III) and Cr(VI) were 1.636μg/ml and 0.126μg/ml. The method has been used for the determination of Cr in waste water and soil. It is both convenient and selective.The forth chapter is the research on the simultaneous separation and determination of NO₃^-and NO₂^- by using RP-HPLC. Anew method is established on ODS2 column(4.6×250mm, 5μm) with methanol-water including TBA·OH(2mmol/L) and 0.06mmol/L (pH=6.00) of Na₂HPO₄ as mobile phase at a flow rate of 0.7 mL/min and detected at 210 nm. The detection limit for NO₃^-and NO₂^- were 0.069μg/ml and 0.092μg/ml. It is a convenient method and can be used to determine water fast.