THE ADSORPTIVE DIFFERENTIAL-PULSE POLAROGRAPHIC PEAK FOR THE LANTHANUM-ARSENAZO I-TEA COMPLEX

An azo-dyestuff, arsenate I, and its complex with lanthanum were studi ed by differential pulse polarographic (DPP) and spectrophotometric me thods. It was found, that arsenate I (AI) forms an additional cathodic peak in the presence of lanthanum ions in triethanolamine buffer (TEA ) pH 8-9. The influence of TEA on lanthanum-arsenazo I complex was exp lored. The composition of the La-AI complex was era mined by the mole ratio- and continuous variations methods. The dependence of complex pe ak current on TEA concentration, pH, the arsenate I concentration was studied, and it has been found that peak current of the complex is pro portional to lanthanum concentration in the range 5x10(-7)-8x10(-6) mo l l(-1). The influence of foreign ions on the complex peak was studied . The complex peak has been proven to be of adsorptive nature by elect rocapillary curves and by measurements of the complex limiting current as a function of corrected height of mercury column in DC polarograph y.