| The improvement of living standard attaches more importance to the research of detection method for the toxic and nutritional elements that have a close connection with the health of people. In this paper the detection method of trace toxic elements in chinese herbal medicine and nutritional elements nutritional elements in food was studied by hydride generation atomic fluorescence spectrometry using intermittent flow system. The high sensitive methods for lead, cadmium, mercury, germanium and zinc have been established. And the effects of enhancing reagents on hydride generation and the release and elimination of interference were discussed. The hydride generation of lead has a high efficiency only in the presence of oxidants or complex agents, which is different from forming-hydride elements. In chapter 2, the simultaneous generation of lead hydride and mercury vapor using potassium ferricyanide and dichromate as oxidants in the medium of citric acid was presented. The mechanism of effect from oxidants and complex agents on the hydride generation was presumed. In addition the hydride generation facilitated by thiourea, ascorbic acid and cobalt ion was proposed and applied to the simultaneous determination of trace cadmium and mercury in Chinese herbal medicine by atomic fluorescence spectrometry. In chapter 3, the hydride generation of nutritional elements of germanium and zinc was investigated. The hydride generation of germanium commonly took place in the acid medium of phosphor acid. The hydride generation with alkaline mode established in this paper greatly enhanced the sensitivity of germanium determination by atomic fluorescence spectrometry. The interference of some coexisting elements was eliminated in alkali medium. The novel enhancing reagent developed in recent years, surfactant, was investigated in detail on improving the hydride generation processes of zinc thermodynamically and kinetically. The nature of zinc hydride was worked over. |
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