Study On Determination Of Copper,Manganese And Selenium By Atomic Fluorescence Spectrometry

Heavy metals are widely distributed in the atmosphere, water, soil and organisms. They get into the human body through the ways such as industry, transportation and life. the heavy metals can interact with proteins and enzymes, making them lose activity in the human body, being enriched in some organs and threatening to human health directly. Copper, manganese and selenium are required trace elements for life activities, but they are toxic to the human body above a certain concentration. For example, when copper is more than a certain amount, it gives rise to lesions in brain tissue and nerve cells, and cause a movement disorder and mental changes; Overdose manganese can damage the function of the nervous system. And excessive selenium can lead to poisoning, make people numbness of limbs and take off nails, hair loss, and even hemiplegia. Because they cannot go microbial degradation and various forms of mutual conversion and migration, thus, the determination of the content of heavy metals is very important and necessary to ensure the safety of human life. there are many ways to determine copper, manganese and selenium, however, the methods we studied in this paper have not yet been reported.Atomic fluorescence spectrometry(AFS) is an analytical technique which have been developed since1960’s. The technique has many virtues such as simple spectral line, high sensitivity, low detection limit and less disturbance. Hydride generation (HG) technique has the advantages of separating from matrix, enriching elements, and high sampling efficiency, apting to realize automatic analysis and speciation. This paper consists of two parts, the first part: determination of copper content in the Chinese herbal medicine and manganese content in manganese slag indirectly with atomic fluorescence spectrometry. The second part:determination of selenium in brass, lead ingots and manganese slag directly by hydride generation-atomic fluorescence spectrometry(HG-AFS). The innovation points of this paper are that applying the indirect measurement method expanded the scope of determination by atomic fluorescence spectrometer, and at the same time we used a new masking agent in the determination of selenium by AFS, the results are satisfactory.A method for indirect determination of copper in Chinese herbal medicine by AFS was proposed. Cul was reacted with HgI42-to form the Cu2HgI4in acidic medium, and extractable with isoamylol. The Hg compound in organic phase was determined by AFS, and the amount of Hg which was found was converted into contents of Cu in sample, the effects of extraction condition and other factors on the determination were investigated. In the optimum experimental condition, a linear relationship of0.01～0.1mg/L Cu was obtained. The method showed a detection limit of0.0035μg/mL Cu and relative standard deviation of0.8～2.4%.Based on that manganese in its slag enriched and separated by polypropylene pyrrolidone, a water soluble polymer, then the added As(Ⅲ) reduced permanganate in a0.3moL/L sulfuric acid medium, the excess As(Ⅲ) was determined on behalf of Mn. Thus, a novel method was established for indirect determination of manganese in its slag by HG-AFS. Under optimum conditions, manganese content in2.0～16μg/L showed a good linear relationship. The detection limit was0.0091μg/mL.In this paper, after samples were digested with acid and the matrix was masked using poly epoxy succinic acid (PESA) without separation of a large quantity of base in advance, then the trace amount of selenium was determined in brass, lead ingots and manganese slags by hydride generation-atomic fluorescence spectrometry. It was found that Cu and Pd were two important interference elements in determination of selenium with atomic fluorescence spectrometry, in order to eliminate these interferences, this paper compared the same concentrations of citric acid, EDTA, thiourea, potassium ferricyanide and PESA on the masking main interference ions. Finally, PESA was used as masking agent because of better masking effect, non-toxic, non-polluting. The results are satisfactory.