A Polarographic Study of the 2-Aminobutanoate Complexes of Copper(II), Lead(II), Cadmium(II) and Manganese(II)

A Polarographic Study of the 2-Aminobutanoate Complexes of Copper(II), Lead(II), Cadmium(II) and Manganese(II)Toru NOZAKI, Masatomi SAKAMOTO, Junji NAKAGI and Masao MIYAKE Department of Industrial Chemistry, Faculty of Engineering, Ehime University; Bunkyo-cho, Matsuyama-shi 790 Japan Polarographic behaviors of copper (II), lead (II), cadmium (II) and manganese (II) in 2aminobutanoate solutions were studied at ionic strength of 0.4 adjusted with sodium perchlorate. The reversible two-electron reduction waves were obtained in the pH ranges from 1.2 to 4.2and 6.1 to 11.9 for the copper system, from 1.2 to 6.8 and 11.3 to 13.1 for the lead system, from 1.3 to 11.0 for the cadmium system and from 5.7 to 9.7 for the manganese system. Metal complexes, MX+, MX2, MX3-, M(OH)X, M(OH)X2-, M(OH)2X-, M(OH)2X22- for copper, the species of the same types, M(OH)3X2- and M(OH)4x3- for lead, MX+, MX2, MX, M (OH) X, M(OH)x2- for cadmium, and MX+ for manganese were assumed and their stability constants were calculated by Schaap and DeFord-Humes' method. The logarithms of the overall stability constants at 25°C were 8.2, 12.0, 14.3, 11.2, 14.7, 14.9, 16.8 for the forementioned copper complexes, 4.6, 8.8, 12.5, 11.9, 15.1, 15.5, 17.4, 17.6, 18.5 for the lead complexes, 3.8, 6.3, 9.0, 8.2, 10.5 for the cadmium complexes, 3.1 for the manganese complex. The square-wave polarograms suitable for the determination of Ni and Co(II), Zn(II), Mn(II), Cu (II) and Cd(II), Pb(II) at pH 9.3, 12.3, 7.7, 8.9, 13.1, respectively, were obtained in the 2-aminobutanoate solutions of 4.0×103- mol/l. The lower limits for the determination of the metals were 0.6, 0.4, 0.4, 0.2, 0.02, 0.05 and 0.05 ppm, respectively.