Kachan I. Ion associates of molybdic heteropoly acids immobilized onto silica as new analytic forms for the determination of P, Si, Sb, oxidants and reductants.

The dissertation is devoted to the elaboration of the solid-phase reagents on the base of silica gel modified with quaternary ammonium salts of aliphatic and heterocyclic nature suitable for adsorption preconcentration of oxidized and reduced forms of phosphoric and silicic heteropoly acids for solid-phase and test-determination of P, Si, Sb and some oxidants and reductants as аscorbic acid, adrenaline, dopamine, hydrazine and iodiate. The conditions of heteropoly acids recovery with immobilized quaternary ammonium salts have been studied and optimized. The nature of heterophase interaction was investigated with UV/Vis-, IR-, diffuse reflectance and solid-phase spectroscopy methods. The active groups of silica surface are proved to participate in heteropoly acid grafting. It was found that the immobilization of heteropoly acids in the form of ion associate is accompanied with the reagent stabilization. It causes the improving of the chemico-analytical characteristics of the methods of determination ofelements able to form heteropoly acids. It was shown that heteropoly acids fixed in the form of ion associates are the effective redox reagents for determination of oxidants and reductants. The conditions of sorption-spectroscopic and test-determination of P, Sb, Si, hydrazine, ascorbic acid, epinephrine, dopamine and iodate at ppb levels were worked out. Metrological characteristics of the methods proposed were tested in the analysis of model solutions and successfully applied for analysis of real objects.