Formation constants of some mercury(II) complexes determined from their anodic polarographic signals

The formation constants of some Hg(II) complexes have been determined from the anodic polarographic signals for the oxidation of mercury in the presence of the following ligands: thiourea and its phenyl- and diphenyl-derivatives, thiocyanate, ethylenediamine, EDTA, methylthioacetic acid, 2,2'-thiobisacetic acid, 3,3'-thiobispropanoic acid, 2,2'-1,1-methandiylbis(thio)]bisacetic acid and 2,2'-1,2-ethandiylbis(thio)]bisacetic acid. The use of differential pulse polarography and a.c. polarography instead of d.c. polarography increases the accuracy and precision of the potential measurements and, as a consequence, of the stability constants determined. The results obtained by the different methods are compared.