Applications of Square Wave Polarograph in Non-Ferrous Metal Analysis

Abstract

Scope and limitation of square wave (S.w.) polarogaphic method of analysis, in constrast with those of d.c. and a.c. polarographic methods, have been investigated. Procedures for the analysis of metallic impurities in non-ferrous metals by s.w. polarographic method have been developed. The procedures have been applied in practice. The results and some comments on the method were given. By s.w. polarographic method Bi(lll), Sb(lll), Cu(ll), Pb(ll) + Sn(ll, lV) and Cd(ll) gave separated waves, repectively, from 1 N HCL base solution (each 30γ mg/100 ml), while the d.c. polarographic waves of Bi, Sb and Cu and a.c. polarographic waves of Bi and Sb overlapped each other. (each 0.2mg/100m1) The lowest concentration levels for the quantitative analysis of the metals from the state base solution were 50γ/100ml, 30-50γ/100rnl and 20 to 10γ or less/100ml by d.c., a.c., and s.w. polarographic method, respectively. The lowest relative cocentration levels for the determination of Zn in the presence of Cd were ca. 2%, 0.025% and 0.002% relative by d.c., a.c., and s.w. polarographic method, respectively. The change of wave height of s.w. polarograms of Cu and Zn from 0.45 N HCLO (50r/100ml) with the change of the distance between d.m.e. and anode (5-20 mm) was negligibly small. The temperature coefficients of the wave height were generally smaller or even negative. Best results were generally obtained when the dissolved oxygen was removed before electrloysis. The wave heights were very sensitive to the change of droptime. The determination procedures of Pb and Cu (0.0018-0.0027%) in electrolytic tin, Pb and Cu (0.0004-0.0009%) in high pure selenium, and Bi and Pd (0.0001-0.0006%) in electrolytic silber were established. The results obtained by these methods showed a good agreement with those by the dithizone method and d.c. polarographic method. The s.w. polarographic method has several advantages, i.e., it requires less skill in comparison with the dithizone method and smaller amount of the sample, ease of chemical pre-treatment, and shorter time for analysis in comparison with the d.c. polarographic method.