Chloride complexes of gold with rhodanine derivatives and their application in chemical analysis

Structural complexity of natural and industrial objects, necessity of methods of their accurate and quick analysis faces chemists-analysts the relevance of creation of new, sensitive, selective, quick and reliable methods, which should satisfy demands of modern science and production control. Organic reagents and among them azo-compounds are of great importance for working out the new methods of determination. They are characterized by high sensitiveness and at the same time by less selectivity. Modern methods of selectivity increase make possible creation of such conditions for determination, which became specific ones. As is known from literature, n-dimethyl-aminobenzylidenrhodanine is frequently used for determination of gold, while there are only scarce data about azo-compounds’ application in chemical analysis. Goal of our work is increase in number of organic reagents suitable for determination of gold, since gold belongs to the number of elements, determination of microquantities of which in different analytical samples requires search of specific determination methods. Proceeding from scheduled tasks, the goal of Master’s degree work is determination of optimal conditions of reactions of [AuCl4]- 4-sulfophenyl-azo-rhodanine formation, calculation of spectrophotometric characteristics and establishment of possibility of practical application of formed complex, and with this purpose a study of effect of obstructing ions on complex formation, finding the ways of getting rid of this effect, as well as elaboration of new methods of determination of gold on the basis of obtained experimental results and determination of gold in natural and technical objects using this method. As it was established on the basis of research carried out by us, 4-sulfophenyl-azo-rhodanine turns out to be the best among three azo-derivatives of rhodanine: 4-methylphenyl-azorhodanine, 4-chlorinephenyl-azorhodanine. Gold was determined both in natural objects (sulfide ores, quarzites) and in technical objects (production waste). Accuracy of analysis results is verified by determination of gold in reference materials and by comparison of results received by us with results obtained using atomic-absorption and neutron-activation methods.