Acta Chimica Sinica ›› 2012, Vol. 70 ›› Issue (06): 765-769.DOI: 10.6023/A1105071 Previous Articles     Next Articles

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齐蕾a, 齐同喜b   

  1. a 南京大学化学化工学院 南京 210093;
    b 山东理工大学化学工程学院 淄博 255049
  • 投稿日期:2011-05-07 修回日期:2011-11-07 发布日期:2011-12-14
  • 通讯作者: 齐同喜

Oscillography Double Potentiometric Titration of Cadmium(Ⅱ) Using Modified Platinum Electrode

Qi Leia, Qi Tongxib   

  1. a School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093;
    b College of Chemistry and Chemical Engineering, Shandong University of Science and Engineering, Zibo 255049
  • Received:2011-05-07 Revised:2011-11-07 Published:2011-12-14

Cd(Ⅱ) modified Pt-electrode was prepared and the adsorption character of Cd(Ⅱ) on the electrode was studied by cyclic voltammetry. The mechanism of electrode response was discussed. A new method using oscillo-potentiometry for the titration of Cd(Ⅱ) was described by optimizing the testing conditions. In 0.1 mol/L hexamethylene tetramine solution (pH 6.0), Cd(Ⅱ) was titrated with EDTA, and two modified Pt-electrodes were used as bi-indicator electrode system. The end point of titration was determined by an abrupt maximum displacement of the fluorescence spot observed on the screen of the cathodic oscillograph. When Cd(Ⅱ) content was in the range of 9.0×10-4~3.5×10-3 mol/L, the recovery was in the range of 99.8%~100.3%. Furthermore, the modified electrode showed excellent stability and reproducibility. In 1.0×10-3 mol/L Cd(Ⅱ) solution, the values of end point potentials obtained from 13 continuous determinations were all around 37 mV, and the relative standard deviation (RSD) was 0.02%. Moreover, the proposed method has been used in the determination of Cd(Ⅱ) contained in samples with recoveries of 99.71%~100.09% and RSD (n=7) less than 0.81%, which are in accordance with the indicator method.

Key words: oscillography analysis, double potentiometric titration, modified Pt-electrode, Cd(Ⅱ), EDTA