| ( Abstract )Oscillographic chronopotentiometric determination is a kind of direct or indirect determination method for microanalysis or trace analysis using the incision on dE/dt-E or peak height on multi-order differential curve on cathode ray oscillograph. The method has the advantages of simple, convenient, economic and no need of deoxygenating. In addition, the method can be applied to routine analysis and process analysis. Hence the method has extensive application foreground in environment, medicine, metallurgy and other fields. Its application range can be largely broadened by the improvement of the sensitivity of oscillographic determination, by the change of the non-oscillographic active substances to active substances and by other effort. Based on this, new methods of direct and indirect oscillographic determination are investigated in this thesis consisted by four chapters, and main contents are as follows:1.The incision depth of sodium tetraphenyiboron on the cathodic branch of oscillogram would be gotten shallow when the organic ammonium is added to the solution containing sodium tetraphenyiboron because the precipitation reaction is occurred between them. Similarly, the phenobarbital can react with Cd2+ and makes the incision of Cd2+ on the cathodic branch of oscillogram deepen. Based on these oscillographic characteristics, indirect determination method with second order differential simple oscillographic voltammetry of theobromine and phenobarbital can be found. The experimental results indicate that indirect determination method of deposition system would be used successfully when the direct determination of medicine is not so sensitive or the medicine has no oscillographic active. As a result, the sensitivity of the determination for the medicine can be improved significantly and the application field of oscillographic analysis is enlarged accordingly. Compared with gravimetric method and titration method, oscillographic determination of theobromine and phenobarbital has the advantage of rapid, simple and no need of filtering precipitation, so the error caused by filtering is avoided. 2.There are three new experiment phenomena in oscillographic determination about coordination compound of Co2+ Zn2+ and Fe3+: First, PAN can cause a sensitive incision on the oscillogram in NaOH solution, and the incision depth would decrease linearly with the increase of the concentration of Co2+. Second, Alizarin red S (ARS) can yield a sharp incision in 0.1mol/L KBr, but the incision disappeared gradually and a new incision of ARS-Zn coordination compound appeared when Zn2+ is added to the solution. Last, 7-iodo-8-hydroxyquinoline-5-sulfonic acid can produce an incision that decreased along with the increase of the concentration of Fe3+. According to these oscillographic characteristics, second order differential simple oscillographic voltammetry of VB12, zinc gluconate and content of Fe are found. The experimental results showed that the application of coordination system not only can improve the sensitivity of the determination of Co2+ and Zn2+ from 10-5 mol/L to 10-7 mol/L, but also can make the non-oscillographic active substances, Fe3+, be determined. Thus, the investigation of oscillographic determination method in coordination system is an important approach of improving the sensitivity of oscillographic determination and enlarging the application range of oscillographic analysis.3.A new method of the determination for resveratrol, second order differential simple oscillographic voltammetry, is proposed based on the resveratrol oscillographic characteristic caused an incision on cathodic branch of oscillogram at -0.45V (vs. SCE) in 0.2mol/L KOH. The linear range and the detection limit is 2.0×10-6 mol/L～5.0×10-5 mol/L, and 1×10-6 mol/L, respectively. The relative standard deviation for the six times determination for 2.500×10-5 mol/L resveratrol is 1.9%. The determination results showed that simple oscillographic voltammetry with second order differential is a convenient method for its c... |
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