I. V. Kubrakova

Determination of chromium(III) and chromium(VI) in river water by electrothermal atomic absorption spectrometry after sorption preconcentration in a microwave field

A rapid and sensitive method for the differential determination of CrIII and CrVI in river water is described. Chromium species can be separated by sorption on a polymeric Detata sorbent containing conformationally flexible aminocarboxylic groups. Preconcentration using either static or dynamic conditions is possible. Microwave heating energy was used to promote the sorption. Quantitative sorption of CrIII was achieved at pH 7, and that of CrVI at pH 3; hence, complete isolation of the two forms of Cr is possible. The optimum conditions (flow rate and sorbent volume) for sorbent extraction of CrIII and CrVI were evaluated. The technique developed is based on the ability of the sorbent to preconcentrate Cr rapidly under dynamic conditions in the presence of a microwave field. Determination of Cr by electrothermal atomic absorption spectrometry is possible either after desorption or directly in the sorbent phase. The detection limit (based on the 3s criterion) is 30 ng l–1; the technique is characterized by high reproducibility.

Analytical results for the material of the Chelyabinsk meteorite

This paper presents the results of the mineralogical, petrographic, elemental, and isotopic analysis of the Chelyabinsk meteorite and their geochemical interpretation. It was shown that the meteorite can be assigned to LL5-group ordinary chondrites and underwent moderate shock metamorphism (stage S4). The Chelyabinsk meteorite contains a significant fraction (approximately one-third by volume) of shock-melted material similar in composition to the main volume of the meteorite. The results of isotopic analysis suggest that the history of meteorite formation included an impact event approximately 290 Ma ago.

Sorption Preconcentration in Combined Methods for the Determination of Noble Metals

Combined methods for the determination of noble metals with the use of sorption preconcentration with complexing, anion-exchange, and other sorbents are reviewed. Characteristics of sorbents, techniques of sorption preconcentration, and techniques for the preparation of a concentrate for determination are considered. Features of instrumental methods for the determination of noble metals in the analysis of different materials are discussed. Examples of the use of sorption preconcentration in combined methods for the determination of noble metals are given from publications between 1996–2005.

Microwave-assisted sample preparation and preconcentration for ETAAS☆

Abstract The analytical schemes based on microwave pretreatment (including decomposition of samples and sorption extraction of trace elements, carried out either in static conditions or in a flow), followed by the determination of microcomponents with atomic spectroscopy methods, are described. The schemes have been developed for the analysis of geological, technological, biological and environmental samples on noble and heavy metals. Results obtained, as well as main features and benefits of microwave-assisted sample preparation coupled with instrumental determination, in part, electrothermal atomic absorption spectrometry, are discussed.

Migration of platinum, palladium, and gold in the water systems of platinum deposits

In order to explore the behavior of platinum group elements in the ecosystems of mineral deposits, the migration characteristics of platinum and palladium were determined in the pH range typical of surface waters. Model sorption experiments on the precipitation of platinum and palladium on iron oxyhydroxide in the presence of major natural inorganic and organic ligands showed that platinum interacts most actively with an iron oxyhydroxide (ferrihydrite) precipitate within the whole pH range, both in the absence and presence of natural organic substances, whereas palladium is preferentially bound to dissolved, suspended, and sedimentary humic substances. The thermodynamic calculation of coexisting platinum and palladium species is qualitatively consistent with experimental data on the character of accumulation and migration of these elements. The obtained data suggest that the migration of platinum and palladium into highly colored waters in the zones of platinum group element deposits results in their extensive deposition on natural geochemical barriers.

Preconcentration of noble metals with the POLYORGS 4 complexing sorbent under the action of microwave irradiation

The sorption of Au(III), Pd(II), Pt(IV), Rh(III), and Ir(IV) with the POLYORGS 4 complexing sorbent in the static mode was studied at room temperature and on thermal and microwave heating. It was demonstrated that the sorption of noble metals from 1 M HCl and 1 M HNO3 solutions can be substantially accelerated under the action of microwave irradiation. Based on the obtained data, the conditions of the group preconcentration of noble metals for their subsequent determination by the ETAAS and ICP AES methods were selected. The preconcentration procedure was used for the analysis of certified reference material SARM-7B (platinum-containing ore), VT-1 (copper-nickel sulfide ore), and the alloy of copper with noble metals.

Direct determination of trace elements in niobium, tantalum and their oxides by inductively coupled plasma atomic emission spectrometry after microwave dissolution

Abstract Analytical schemes for the determination of trace elements in high-purity niobium, tantalum and their oxides are proposed. The schemes are based on microwave dissolution of the metals and oxides followed by inductively coupled plasma atomic emission spectrometry (ICP-AES) determination of impurities in the solutions. The possibilities of interelement and off-peak background corrections in ICP-AES analysis are discussed. The accuracy of the results obtained is confirmed by the determination of trace elements after a matrix sorption separation procedure. For a number of elements, a comparison of the results obtained by ICP-AES without and with the matrix separation procedure and by electrothermal atomic absorption spectrometry (ETAAS) shows good agreement. The limits of detection for direct ICP-AES determination are in the range 0.4*1.0 μg g−1 for Ba, Ca, Fe, Mg, Mn, Y and La; between 2.0 and 10.0 μ g−1 for B, Cd, Co, Cr, Cu, Hf, Mo, Na, Nb, Ni, Pb, Sr, Ti, Zr and Ta; and for K, Sb and W a detection limit of 20 μ g−1 is achieved. The schemes proposed are intended for rapid routine analysis.

Role of organic matter in the accumulation of platinum in oceanic ferromanganese deposits

In order to elucidate possible processes leading to platinum accumulation in ferromanganese deposits, we analyzed published data on the interaction of dissolved platinum species in different valence states with iron and manganese oxyhydroxides under oceanic conditions and experimentally studied the kinetics of sorption of inorganic and organic complexes of platinum (II) and platinum (IV) on synthetic iron and manganese oxyhydroxides and natural materials (marine colloids, and ferromanganese crust samples). The role of dissolved and suspended particulate aquatic organic matter in the sorption accumulation of platinum was evaluated. Possible reasons for the preferential (compared with other noble metals) accumulation of platinum in oceanic ferromanganese deposits were discussed.

Microwave synthesis, properties and analytical possibilities of magnetite-based nanoscale sorption materials

An approach is proposed to the preparation of magnetic sorption materials based on the synthesis and surface modification of nanomagnetite by organic compounds under microwave heating. The optimum conditions for the preparation of nanomagnetite are found, its structure and particle sizes are studied. Data on the stabilization and modification of the prepared particles by surfactants are obtained. The magnetic materials modified by oleic and mercaptopropionic acids and also by cetyltrimethylammonium bromide are synthesized and thoroughly characterized. Conditions of the formation of a modifying layer are studied and its stability is estimated. Sedimentation properties of the modified adsorbents are studied. The sorption capacity and kinetic properties of the modified nanomagnetite for a number of inorganic and organic natural water pollutants (cadmium, lead, copper, phenol, and toluene) are determined. The possibility of the efficient extraction of heavy metals in the presence of macrocomponents of natural waters is shown and data on the possibility of their desorption are obtained.

New solid extractants for preconcentrating noble metals

New solid extractants are synthesized with the use of imidazolium and phosphonium ionic liquids for preconcentrating noble metals. Ionic liquids are selected and conditions for their immobilization on various solid matrices are found. The adsorption properties of the synthesized solid extractants for platinum(IV) in hydrochloric acid solutions are studied. The solid extractants obtained by binding 1-hexadecyl-3-methylimidazolium bromide and trihexyltetradecylphosphonium chloride to polymeric matrices and multiwall carbon nanotubes possess good kinetic properties and selectivity in 1 M HCl, and can be used to preconcentrate Pt(IV), Pd(II), and Au(III) in combined methods of their determination.