POLAROGRAPHY OF THIOMALIC ACID AT DME

被引:36
作者
SAXENA, RS
GUPTA, KC
机构
[1] Department of Chemistry, Malaviya Regional Engineering College, Jaipur
关键词
D O I
10.1016/0013-4686(68)80082-9
中图分类号
O646 [电化学、电解、磁化学];
学科分类号
081704 ;
摘要
The polarographic behaviour of thiomalic acid (TSH) at the dme has been investigated in presence of 0·1 M KCl and 0·01 % thymol, with respect to the effect of changes in pH, concentration of TSH, drop thne and temperature on the wave characteristics and on the mechanism of the reaction occurring at the surface of the mercury drop. Variations in H+ ion concentration of the medium between 4·0 and 7·0 had a negligible effect on the well defined reversible anodic wave of TSH; at lower (< 4·0) and higher (> 7·0) pH values, ill-defined waves were obtained. The proportionality of wave height with TSH concentrations, √heff and temperature, and a linear plot of E vs log (id - i)/i with slope of 0·061, indicate that the reaction of TSH at the dme is strictly diffusion-controlled and reversible, involving a one-electron transfer process. The current voltage curves over the entire pH range (1·0-10·68) obey the equation TSH + Hg ⇌ TSHG + H+ + e. The anodic wave of TSH at the dme does not correspond to the formation of dithiomalic acid (TSST) but rather to the formation of a mercury compound TSHg in accordance with the above equation The diffusion coefficient and the temperature coefficient of id over the temperature range 31·0-69·5° at pH 7 are 4·494 × 10-5 cm2/s and 1·66% per degree respectively of id with TSH concentration provides a rapid and precise method for the determination of TSH down to 0·20 mM. © 1968.
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页码:1749 / &
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