| Abstract: | The behaviour of the cobalt complex with dimethylglyoxime (DMG), Co(II)A2, at the mercury electrode has been investigated in details. The adsorption phenomena have been observed by both normal pulse polarography and voltammetry with linearly changing potential. Experimental results show that, under the condition of adsorption potentials ranging from ?0.60 to ?0.9 eV (vs. S.C.E.), Co(II)A2 can be adsorbed on the surface of hanging mercury drop electrode (HMDE) very well. The superficial concentrations represents a Langmuir isotherm with both concentration of Co(II)A2 and the preconcentration time. The superficial concentration equation for adsorption voltammetry, corresponding to the condition of the low coverage of the electrode surface, is deduced. The equation has been verified experimentally. The sensitivity of the proposed method, which has been analysed theoretically, is independent on the scan rate and the surface area of HMDE, but depends on the preconcentration time and the diffusion layer thickness. For the 120 sec accumulation, the lower limit of determination is 1.10?9 M. |
