A Novel Method Of Electrokinetic Extraction And Atomic Fluorescence Spectrometry For The Determination Of Arsenic And Selenium

Arsenic and selenium are elements which have a significant impact on people and environment, so it is necessary to have further study in order to analyze the lower concentration of arsenic and selenium in environmental and industrial samples. The paper introduced a novel sample pre-concentration and analysis method, electrokinetic extraction, based on the foundation that electrochemical hydride generation and chemical hydride generation coupled to atomic fluorescence spectrometry. A new instrument introduced by our work was resigned for the compatibility of electrokinetic extraction and electrochemical hydride generation process, which was coupled with atomic fluorescence spectrometry and then be applied for the determination of arsenic species in waters. What’s more, the sole electrokinetic extraction device applied to ordinary and classical chemical hydride generation method to per-concentrate and analyze selenium in waters successfully with lower detection limit. The paper included the following sections:The first chapter described the contents of experimental objects, arsenic and selenium in the natural environment, and then introduced their impacts on people and the living being. Beside, the application and advantages of the technology were generalized that the electrical field as an assistive power combined to liquid extraction, solid phase extraction and membrane extraction, and especially the theoretical basement and device of electrical membrane extraction were highlighted. And then, the development, characteristics, applications and interferences of chemical hydride generation and electrochemical hydride generation methods were discussed. Moreover, some details of the electrochemical hydride generation cell were explained for comparison with electrokinetic extraction device.The second chapter studied the method that electrokinetic extraction and electrochemical hydride generation hyphenated with atomic fluorescence spectrometry. Firstly, the design of an H-type instrument and the selection of electrode materials were explored and optimized considering that the instrument was focused on the compatibility of two pre-treatment technologies. Then, the appropriate pH of samples and acceptors was adjusted to achieve arsenic species determination, In the experiment, the time and voltage during extraction process, as well as the electrolytic current and sample flow rates over the procedure of electrochemical hydride generation were optimized. The results of experiments certificated that the H-type electrolytic cell coupled to atomic fluorescence spectrometry is an easy to assemble, simple to operate analytical method with satisfactory separation efficiency.Based on the study of the electrokinetic extraction, the third chapter proposed the method that electrokinetic extraction coupled to chemical hydride generation atomic fluorescence spectrometry, which was used for the determination of selenium in waters. For the design of sole electrokinetic extraction unit, the size of the chambers and the distance of electrodes were optimized. And the difference resulted from the change of samples and the accept phase was discussed. Besides, the experimental conditions of electrokinetic extraction and chemical hydride generation atomic fluorescence spectrometry were optimized. The study proved the method that electrokinetic extraction combined with chemical hydride generation atomic fluorescence spectrometry is an economical and time-saving pre-concentration and separation technology with improved sensitivity.