Electrochemically Oxidization Modified Glassy Carbon Electrode And Its Application In Electroanalysis

Electrochemically oxidation modified glassy carbon electrode is oxidation of glassy carbon electrode though anodic polarization under certain conditions. This treatment changes the structure of the electrode surface and forms a porus film which contains many functional groups. It is proved that these functional groups have special electro-activity to some substances such as quinines, nitrobenzenes and some metal ions. Based on this charicteristic of the electrochemically oxidation modified glassy carbon electrode, the methods for the determination of Vitamin K1 and K3, nitrobenzenes and cadmium by voltammetry were established.In this study, the pretreatment parameterss of electro-oxidation of glassy carbon electrode, such as pretreatment medium, oxidation potential and oxidation time, and the parameters of voltammetric measurement of Vitamin K1 and K3, nitrobenzenes and cadmium, such as suppoting electrolyte selection, accumulation time and the potential scan rate, were optimized carfully. The electro-reaction mechanism of Vitamin K1 and K3, nitrobenzenes and cadmium on the electrochemically oxidation modified glassy carbon electrode was discussed.In 0.1mol/L hydrochloric acid solution, a pair of sensitive redox peaks were observed at about -0.025V for Vitamin K1, and the peak current of Vitamin K1 is proportional to its concentration from 0.5mg/L～6mg/L.The detection limit of Vitamin K1 is 0.2mg/L. The redox peaks of Vitamin K3 were appeared at about +0.060V. The peak current showed linear response with its concentration in the range of 0.1mg/L～10mg/L, and the detection limit is 0.03mg/L. The method had been used for the determination of VitaminK1 and K3 in drug, the results agreed well with those obtained by the mehtod of pharmacopeia.The voltemmetric responses of nitrobenzene, 3-nitrotoluene, 3-nitrochlorobenzene, 1,2-dinitrobenzene, 1,3-dinitrobenzene, 2,4-dinitritiluene and 2,4-dinitrocnlorobenzene on the modified glassy carbon electrode were investigated. Under the optimum experimental conditions, linear ranges for the seven compounds were 0.1mg/L～10mg/L, 0.1mg/L～ 6mg/L, 0.2mg/L～8mg/L, 0.2mg/L～6mg/L, 0.4mg/L～10mg/L, 0.2mg/L～4mg/L, and 0.2mg/L～8mg/L, respectively. The detection limits for the seven compounds were 0.01mg/L, 0.01mg/L, 0.03mg/L, 0.01mg/L, 0.03mg/L, 0.03mg/L and 0.03mg/L, and the RSD were 3.8﹪, 6.6﹪, 7.5﹪, 6.2﹪, 4.7﹪, 6.6﹪and 3.7﹪, respectively.The electrochemical behavior of cadmium on the modified glassy carbon electrode was also studied. Under the optimum conditions, the linear ranges were 0.2mg/L～0.8mg/L and 1mg/L～10mg/L. The detection limit is 0.1mg/L.