SORPTION PRECONCENTRATION AND DETERMINATION OF ANTIMONY AND TELLURIUM ON MODIFIED SILICA GEL

Antimony and its compounds are widely used in industry, making it one of the priority pollutants of air and the aquatic environment. Excess of antimony is selectively concentrated in a thyroid gland, a liver, a spleen. The manifestation of the toxic effect of antimony is a variety of impaired functions of the human body, so the content of this element in drinking water normalizes is at the level of 5 μg/l. Recently, tellurium has also been increasingly the subject of research by analyst chemists. Tellurium is a biologically active element and its concentrations in the environment are strictly regulated. According to sanitary rules and regulations, the maximum allowable concentration of tellurium in drinking water is 0.01 mg/l. The article is devoted to the elaboration of solid-phase reagents based on the quaternary ammonium salt (QAS) immobilized on silica gel and to the development on this basis of sorption-spectrometric and visual test-methods of the determination of Sb(III) and Te(IV). The mechanism of the interaction between QAS immobilized on silica gel and the anions iodide complex of antimony and tellurium was studied. It was found that it proceeds by the ion-associative mechanism. Conditions of sorption preconcentration of anionic complexes of elements were optimized. For the quantitative sorption of antimony (III), the weight of the sorbent is 0.020 g and the volume of the solution is 25.0 ml. Under these conditions, the anionic complex is sorbed by 98%. The maximum concentration ratio is 1.25 l/g. The sorption equilibrium in the system is established in 20 minutes. For the quantitative extraction of tellurium (IV), the optimal weight of the sorbent is 0.050 g and a solution volume of 25.0 ml. Under these conditions, the degree of sorption reaches about 80%. The maximum concentration ratio is 0.4 l/g. The sorption equilibrium in the system is established in 15 minutes. The influence of foreign ions on the extraction degree of the investigated elements, and also on the magnitude of analytical signal, was studied. Sorptionspectrometric and visual test-methods of the determination of Sb(III) and Te(IV) in pharmaceutical preparation "Antimonium tartaricum" and "Tellurium Metalicum".

X-Ray Fluorescence Determination of Trace Elements in Vitamin-Mineral Complexes and Medicinal Herbs Using Chemically Modified Polyurethane Foam Sorbents

In this paper we proposed the method of X-ray fluorescence (XRF) determination of some essential trace elements in medicinal herbs and vitamin-mineral complexes at the level of 100-101 mg/ml. To increase sensitivity and selectivity of the determination we simple and effective approach based on the extraction of metal ions from aqueous solutions with chemically modified polyurethane foam sorbents followed by direct XRF analysis. The conditions of sorption preconcentration of Co(II), Ni(II) and Zn(II) ions with modified sorbents were optimized. The proposed approach is used for the determination of trace elements in several kinds of medicinal herbs (coltsfoot leaves, nettle leaves and yarrow herb) and vitamin-mineral complexes («Alfavit», «Vitrum» and «Multi-tabs»).

Dc arc emission analysis of rare earth metals and their oxides with sorption preconcentration of impurities

The analytical capabilities of arc atomic emission determination of As, Bi, Sb, Cu, Te in rare earth metals (REM) and their oxides after preparatory group concentration using S,N-containing heterochain polymer sorbent are studied on a high-resolution spectrometer “Grand- Extra” (“WMC-Optoelectron-ics” company, Russia). Sorption kinetics and dependence of the degree of the impurity extraction on the solution acidity are analyzed to specify conditions of sorption concentration. To optimize the procedure of arc atomic emission determination of As, Bi, Sb, Cu, and Te various schemes of their sorption preconcentration and subsequent processing of the resulted concentrate with the addition of a collector at different stages of the sorption process have been considered. Graphite powder is used as a collector in analysis of rare earth oxides due to universality and relative simplicity of the emission spectrum. Conditions of analysis and parameters of the spectrometer that affect the analytical signal (mass and composition of the sample, shape and size of the electrodes, current intensity and generator operation mode, interelectrode spacing, wavelengths of the analytical lines) are chosen. The evaporation curves of the determinable impurities were studied and the exposure time of As, Bi, Sb, Cu, and Te in the resulted sorption concentrate was determined. Correctness of the obtained results was evaluated using standard samples of the composition and in comparisons between methods. The results of the study are used to develop a method of arc chemical-atomic emission analysis of yttrium, gadolinium, neodymium, europium, scandium and their oxides in a concentration range of n x (10-2 - 10-5) wt.%.