⎯Adsorbents based on silica chemically modified by sulfur-containing groups (dithiocarbamate, thiodiazolethiol, mercaptophenyl, and aminobenzothiazole) quantitatively extract (recovery ≥99%) platinum(IV) from solutions ranging from 4 M HCl to pH 6. Under the conditions of the adsorption separation of platinum(IV), rhenium(VII) is not extracted and remains in the solution. The subsequent quantitative (98-99%) adsorption of rhenium(VII) is achieved in the presence of a 1000-fold excess of tin(II) chloride. Adsorption on the surface of adsorbents leads to the formation of platinum(II) complexes with sulfur-containing groups, luminescent at 77 K on irradiation with UV light. The luminescence spectra of surface platinum(II) complexes are located in the region of 550-700 nm. In the adsorption of rhenium(III) in the presence of tin(II) chloride, intensely colored brown complexes of rhenium formed on the surface of adsorbents. Electron paramagnetic resonance showed that, in the surface complexes, rhenium is in the oxidation state 2+. Silicas chemically modified by sulfur-containing groups were used in the development of procedures for the sequential isolation and determination of platinum and rhenium in solutions after the decomposition of aluminum-platinum-rhenium catalysts.

Silica gel chemically modified with dithiocarbamate groups (DTCS) was used for separation and preconcentration of precious metals and their subsequent determination in geological samples and their processing products by inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass-spectrometry. DTCS was characterized by TGA/DSC, FT-IR, and CHNS-analysis. DTCS quantitatively extracted Au 3+ , Pd 2+ , Pt 2+ , Pt 4+ at 20°C from 0.5-4.0 M HCl media and Rh 3+ , Ir 4+ , Ru 4+ ,Os 4+ at 95°C in the presence of 0.025M SnCl 2. Two-column procedure was proposed to separate precious metals from matrix components and to separate kinetically inert precious metals from kinetically labile ones.

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