Preliminary study of nickel,ferric, lead,and copper oxinates in reactions of reextraction through the exchange of ligands: The use of chloroform solutions of the copper oxinate in the spectrophotometric determination of cyanide

In this paper a systematic study of four metallic oxinates (ferric, nickel, lead, and copper complexes) is carried out, determining some characteristics of the organic solutions of these complexes in reactions of reextraction by the exchange of ligands. These reactions are based on the decoloration produced in organic solutions of colored complexes when they are mixed with aqueous solutions of anions. The study of some characteristics and the qualitative tests shows that only the copper oxinate is interesting for quantitative purposes because its solutions in chloroform are decolored at very low concentrations of oxalate ethylenediamine tetraacetate, sulfide, and cyanide.The application of this study to the indirect spectrophotometric determination of cyanide is carried out. The decoloration varies linearly with the cyanide concentration between 10 and 50 ppm for a phase volume ratio 1:1. Finally, the error, reproducibility of the method, nature of the exchange reaction, and interferences of foreign ions are also established.