Chemical Vapor Generation Coupling With Atomic Fluorescence Spectrometry For Determination Of Selenium And Mercury

Atomic fluorescence spectrometry has become one of the most important inorganic element analysis method for the advantages of simple structure, high sensitivity, low detect limit, the simple line, good selective, analysis of wide linear range, and multi-element simultaneous determination, and so on. However, a single atomic fluorescence spectrometry can't accurately determine trace elements of complex samples. Therefore, we need to separate the elements of determination from substrate, and determined it by atomic fluorescence spectrometry.Chemical vapor generation is a technology of transferring chemical elements to the form of volatile elements. It may separate the elements of determination from complex substrate effectively. This method has the characteristic of elimination of substrate interference and realization of valence and species analysis, and so on.In this thesis, base on the studying of the chemical vapor generation and coupling with atomic fluorescence spectrometry, established the method of determination of selenium in high purity tellurium and mercury in lake water, and verified by experiments that the method has high sensitivity and low detect limit.Part one:at the base of studying atomic fluorescence spectrometer, the working conditions of the instrument, such as hollow cathode lamp current, photomultiplier tubes negative high voltage, atomizer height, the rate of carrier gas flow and shielding gas flow, and the various treatment conditions of the samples were optimized in detail. The following, we established three methods of separation and enrichment and coupling with atomic fluorescence spectrometry that can successfully determine trace Se in high purity tellurium. First, the method of co-precipitation-Atomic Fluorescence Spectrometry was used to determine the selenium in highly pure tellurium, the detect limit of selenium was 0.54ng/mL and recovery was 80% -90%. Second, the method of extraction-atomic fluorescence spectrometry which was used for determination of selenium in highly pure tellurium, the method of calibration curve correlation coefficient was 0.9960, the detect limit was 0.60ng/mL, the recovery was 90%-108%. The high sensitivity of this method can meet the requirements of the analysis for actual sample. Third, coupling the method of distillation with atomic fluorescence spectrometry was used to determine tellurium in highly pure selenium, the recovery were 96%-106%.Part two:based on the technique of cold chemical vapor, we designed the gold traps device. Coupled it with the atomic fluorescence spectrometer, and then we established a new method for determining trace mercury in the lake water. With this method, the factors of the amount of oxidant and reducing agent, the accumulation time which affects the analysis was studied systematically. Under optimal experimental conditions, we studied the impact of Co2+, Ag+, Cu2+, Al3+, Ni2+ and other ions on the determination of mercury. Results show that the ions allowed the amounts of Cu2+ and Ni2+ were 0.2mg/mL, and the amounts of Ag+ and Al3+ were 5μg /mL. Compared with traditional technology of cold chemical vapor, this technique showed stronger anti-interference ability to the metal ions. It successfully achieved the determination of trace mercury in the lake water. Under optimal experimental conditions, the mercury detect limit was 0.5ng/L, the recovery was 93%-106%.