Study And Application On The Determination Of Selenium, Nickel And Cadmium By Oscillopolarography

The content of trace elements has great relation to human health. The determination of trace elements plays an important role in the essay of environmental science, medicine, food and clinic. So, establishing quick, simple, sensitive and less disruptive methods to determinate trace elements are very valuable in application.The electrochemical property of the polarographic adsorptive complex wave produced by selenium and glutathione (GSH), nickel and dimethyl glyoxime(DMG), cadmium and KI discussed in this paper. These methods have been applied to determine some samples, and the results are fine. The contents are as follows:1. The electrochemical characters of the complex of Se(Ⅳ) and GSH on the mercury electrode have been studied by oscillopolarography. In NaOH medium, Se(Ⅳ) has a sensitivitive catalytic polarographic wave at -940mV(vs.SCE)with GSH. The linear relationship between concentrations of Se(Ⅳ) and the catalytic polarographic peak heights was in the concentration range of 4.0×10-7～8.0×10-6mol/L. Detection limit of this method is 2.0×10-7mol/L with relative standard deviation below 5%. Optimized the experiment conditions, and estimated the mole ratio of the Se(Ⅳ) to GSH is 1:6. The results of experiments (the effect of Hg column height, scan rate, quiet time etc. on the peak current) prove that this polarographic wave has adsorptive character. This method is simple, rapid, sensitive, and has been successfully applied to determine the trace selenium in biological samples.2. The electrochemical characters of the complex of Ni(Ⅱ) and DMG on the mercury electrode have been studied by the oscillopolarography. In Na2B4O7 medium, Ni(Ⅱ) has a sensitivitive polarographic wave at -1060mV(vs.SCE)with DMG. The linear relationship between concentrations of Ni(Ⅱ) and the derivative polarographic peak heights was in the concentration range of 8.0×10-8~2.0×10-6 mol/L. Detection limit of this method is 8.0×10-8mol/L with relative standard deviation below 5%. Optimized the experiment conditions, and estimated the mole ratio of the Ni(Ⅱ) to DMG is 1:2. The results of experiments (the cyclic voltammograms, the effect of Hg column height,...