A method for the selective preconcentration of Cr(VI) using a silica gel- based sorbent chemically modified with methyltriphenylphosphonium groups, followed by determination by inductively coupled plasma atomic emission spectroscopy or a test- method has been proposed. Cr(VI) is effectively removed by the sorbent in the pH range of 3.5-5.5. In this pH range, there is no sorption of Cr(III), which makes it possible to effectively separate Cr(VI) from Cr(III). When a solution containing Cr(VI) is passed through a column with a sorbent, a yellow- colored zone appears in the column, the length of which is proportional to the Cr(VI) content in the column. Cr(VI) can be quantitatively desorbed with 5 mL of 2M HCl and determined in the eluate by inductively coupled plasma atomic emission spectrometry. The sorbent withstands at least 20 "sorption- desorption" cycles. The efficiency of separation and the accuracy of adsorption- atomic- emission and test- determination of Cr(VI) were confirmed by "added- found" method and by analysis of water samples with chromium content determined using a certified method.

Phosphoric acid-modified biosorbents were synthesized from wood and agricultural wastes (pine sawdust, barley husks and sprouts, rice husks) with controlled degrees of phosphorylation for preconcentrating rare earth elements (REEs) in lignites prior to inductively coupled plasma optical emission (ICP-OES) analysis. The biosorbents were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) to assess morphology and thermal stability. The biosorbents enabled quantitative recovery of REEs from acidic media (0.5 mol L-1 HCl to pH 5.5) and demonstrated high selectivity for REEs over non-ferrous, alkaline, and alkaline earth metal ions at pH 1.0. Adsorption capacity increased proportionally with the degree of phosphorylation in both batch and dynamic preconcentration modes. A solid-phase extraction method was optimized: 200 mL of sample solution (pH 1.0) was passed through a biosorbent column at 1 mL min-1, followed by elution of REEs with 10 mL of 6 mol L-1 HNO3 (preconcentration factor of 20). Method accuracy was validated using spiked solutions. The developed approach achieved detection limits of 0.001-0.048 mu g g-1 and was successfully applied to determine REEs in lignites from the Krasnoyarsk Krai (Russia).

A complex approach to the extraction of gallium from a carbon concentrate (CC), a waste product of the aluminum industry, was considered. Ashing of CC made it possible to remove the main component - carbon and obtain ash, which is an oxide mineral-like compound, from which gallium was leached with solutions of inorganic acids and their mixtures. The maximum degree of leaching (98%) of gallium was achieved with 6 M HCl for ash after ashing the CC at 600 degrees C. It was shown that Purolite anion exchangers with highly basic tertiary and quaternary ammonium base groups recovered gallium(III) from 2 to 10 M HCl, where the sorption equilibrium was attained after 60 min. The maximum extraction was observed from 6 M HCl. Under optimal conditions, the maximum sorption capacities for gallium(III) were achieved for Purolite A300 (2.7 mmol g(-1)) and Purolite A500 (2.2 mmol g(-1)) sorbents. Gallium(III) was quantitatively (99%) eluted from the sorbents with distilled water. Sorption of gallium(III) and its subsequent desorption with water made it possible to separate it from the predominant amounts of transition metal ions: Fe(III), Ni(II), Co(II), Zn(II), V(V) and other cations: Al3+, Ca2+, Mg2+, Na+ and K+. The addition of sodium hydroxide to the concentration of 200 g L-1 resulted in the cementation of gallium on aluminum gallama (liquid gallium-aluminum alloy).

For the concentration and separation of inorganic forms of arsenic, it is proposed to use aluminum oxide modified with polyhexamethylene guanidine (Al2O3-PHMG) and silica chemically modified with disulfide groups (DSS). The presence of protonated amines on the surface of modified aluminum oxide makes it possible to effectively concentrate anionic forms of arsenic from aqueous solutions. Arsenic(V) is quantitatively extracted by aminated aluminum oxide from solutions at a pH of 1.8-7.5 with a sorption equilibrium time not exceeding 5 min. The sorption capacity of Al2O3-PHMG with respect to As(V) is 55 mu mol/g. To extract As(III), it is proposed to use a DSS sorbent that quantitatively extracts arsenic from solutions in the pH range 4.0-7.5. The sorption capacity of the DSS was 110 mu mol As(III) per 1 g of sorbent. In the dynamic mode of concentration of inorganic forms of arsenic, the optimal conditions are pH 4.5. The flow rate of the solution is 1-1.5 ml/min.The volumeof the passed solution is 300 ml at an analyte concentration of 1 mg/l. Quantitative desorption of As(V) from the surface of Al2O3-PHMG is achieved by 10 ml 0.05 M NaOH, adsorbedAs(III) from the surface of DSS -10 ml 2 M HCl. For separate concentration and determination of As(III) and As(V), a system of two sequentially connected concentrating cartridges was used: the first was filled with a DSS sorbent, the second with an Al2O3-PHMG sorbent. The pro-posed system was used to concentrate and separate inorganic forms of arsenic directly at the sampling site -natural underground and well drinking waters of Tyva Republic. The subsequent ICP-AES determination of arsenic was carried out after its desorption in laboratory conditions.

Silica-based adsorbents (Silica gel 60 and Silochrom S-80) chemically modified with aminophosphonic groups with various surface concentrations have been proposed for the preconcentration of rare earth elements (REE). The resulting adsorbents were studied by FT-IR, SEM, TGA and compared with unmodified matrices. Adsorbents quantitatively extracted REE from solutions with pH 1.0-5.0. Solid phase extraction at pH 1.0-2.0 made it possible to quantitatively separate rare earth elements from the predominant amounts of accompanying metal ions. An increase in the concentration of aminophosphonic groups on the silica surface led to an increase in the adsorption capacity of the adsorbent for Gd(III) both in batch and dynamic modes. A technique for solid-phase extraction followed by inductively coupled plasma optical emission (SPE-ICP-OES) determination of REE has been developed; it includes pumping 200 mL of the sample solution (pH 1) through a mini-column with an adsorbent at a flow rate of 1 mL min(-1), eluting REE with 10 mL of 1 M HNO3 (preconcentration factor 20), and then determination of the elements in the eluate by ICP-OES. The technique was used for the determination of REE in lignite and coal from the Krasnoyarsk Krai (Russia). The accuracy of the results was confirmed by comparison with ICP-MS determination and by the analysis of certified reference material of coal ash.

The conditions for solid-phase extraction of the synthetic food dye Fast Green FCF (E 143) by basic and modified with polyhexamethylene guanidine alumina (Al2O3-PHMG) were deter-mined. The equilibration time for extraction of E143 dye was 15 min for the both adsorbents. Quan-titative extraction of E143 dye with Al2O3-PHMG was achieved in the ranges of pH 1.0-3.0 and pH 6.5-7.5. The maximum extraction of the dye by basic alumina was observed in the pH range of 2.0- 5.0 and did not exceed 80%. The adsorption capacity of adsorbents for E143 dye was 20 ,umol g-1 for Al2O3, 35 ,umol g-1 for Al2O3-PHMG at pH 1 and 11 ,umol g-1 at pH 6.5. The experimental ad-sorption isotherms for Al2O3-PHMG at pH 1 and pH 6.5 are best fitted the Langmuir model. The adsorption isotherm for Al2O3 in the segment of growth of the adsorption capacity is best fitted the Freundlich model. When extracting E143 dye, the surface of the adsorbents acquired a color char-acteristic for the dye in solution. In this case, an intense band with a maximum at 620 nm was observed in the diffuse reflectance spectra of the surface of the adsorbents. The procedure of ad-sorption-photometric determination of E143 dye in the variant of diffuse reflectance spectroscopy using Al2O3-PHMG was proposed. Limit of detection, calculated by the 3s -criterion, was 7 ,ug L-1 when using 10 mL of solution. The analytical range of dye concentrations was 0.02-3.0 mg L-1. The relative standard deviation did not exceed 0.08 (n=10). The selectivity of preconcentration of E143 at pH 1.0 was higher than at pH 6.5. The developed procedure was used for determination of the Fast Green FCF dye in a model solution based on the soft drink.

Adsorbents based on silica gel chemically modified with arch structure 2-aminophenyl disulfide (DSS) and bis[3(triethoxysilyl)propyl]tetrasulfide (TSS) groups have been synthesized. The proposed adsorbents quantitatively extracted (extraction -99 %) only palladium(II) among all platinum metals from solutions of 2 M HCl - pH 4. Quantitative extraction of Pd(II) was not interfered with 106-fold excesses of alkaline, alkaline-earth, 104-fold excesses of non-ferrous metals and iron, 102-103-fold excesses of other platinum metals. Pd(II) was eluted quantitatively (desorption -99 %) from the adsorbents surface with 5-10 % thiourea solutions and could be determined in the eluate by inductively coupled plasma optical emission spectrometry (ICP-OES). The adsorption capacity of DSS and TSS adsorbents was not changed after 5 adsorption-elution cycles. The limit of detection of palladium in the analyzed solution, calculated using the 3 s-criterion, was 0.1 mu g/L for solid-phase extractioninductively coupled plasma optical emission spectrometry (SPE-ICP-OES) method with a preconcentration factor of 50. Intensive yellow-orange color of the palladium surface complex was used in the development of express test-methods for its determination. SPE-ICP-OES and test methods were used in the determination of palladium in certified reference materials of sulfide copper-nickel ore and products of its technological processing.

Министерство науки и высшего образования Российской Федерации Российская академия наук Научный совет по неорганической химии РАН Научный совет по аналитической химии РАН Научный совет по химической технологии РАН Российское химическое общество имени Д.И

A simple and available method for on-line preparation of the adsorbent and solid phase extraction procedure for multi-element determination by inductively coupled plasma mass spectrometry (ICP-MS) has been proposed. The adsorbent (Al2O3-PB-AC) was synthesised by sequential impregnation of Al2O3 with Polybrene (PB) and Alizarin Complexone (AC). Cd(II), Cr(III), Ni(II), Pb(II) and Zn(II) were quantitatively recovered using Al2O3-PB-AC from aqueous solutions at pH 6.5 and at a flow rate of 1.0 mL min(-1). All the elements can easily be eluted by 3.0 mL 0.5 M HNO3. A mini-column packed with 0.100 g Al2O3-PB-AC retained all elements quantitatively from up to 50 mL multi-element solution with an enrichment factor of 16.7. The relative standard deviation for five replicate determinations was 3.5%, 7.3%, 6.2%, 7.4% and 4.7% for Cd(II), Cr(III), Ni(II), Pb(II) and Zn(II), respectively, for determination of 5 mu g L-1 level. The developed method was applied for SPE-ICP-MS determination of Cd, Cr, Ni, Pb, Zn in snow and river waters.

strategic issue for rare metals manufacturers is availability of the own raw material base. Previously unused resources which include the lignites located at central watershed of the Yenisei river are becoming important due to depletion of traditional sources of raw materials. The comprehensive approach to the processing of the lignite which ensures the formation of sublimates germanium -enriched to 1,8 wt.% and ash rare earth metals-enriched to 1,2 wt.% was proposed. The regularities of rare earth metals leaching from ash residue with obtaining rich solutions suitable for further processing using selective sorbents have been studied.

Gallium and germanium are practically important trace elements used in various high-tech areas as photovoltaics, electronic equipment, semiconductor gamma-ray detectors, infrared equipment, etc. New secondary raw materials for their extraction are a subject of a thorough search. In this study, new evidence of the presence of germanium and gallium in the wastes from the Hall–Héroult process was demonstrated and comprehensively discussed, and a method of their extraction was proposed. The concentration of gallium in the carbon dust reaches 0.02% and the concentration of germanium is below the detection limit. After the treatment of carbon dust, the concentration of trace elements is drastically increased. The carbon concentrate being a product of carbon dust treatment can be combusted to accumulate gallium in the ash while germanium distributes between the ash and the sublimates from the concentrate combustion due to the volatility of monoxide GeO. The concentration of gallium in the ash reaches 0.5 wt.% and the concentration of germanium highly depends upon the combustion temperature and the partial pressure of oxygen. The results of trace elements extraction in the acidic and basic environment are shown.

The laws of germanium(IV) adsorption by adsorbents based on alumina or silica layer-by-layer modified with polyhexamethylene guanidine (PHMG) and tiron (Al 2 O 3 –PHMG–tiron and SiO 2 –PHMG–tiron) were studied. The effects of Lewis acid sites of alumina on the anchorage of modifier reagents and on germanium(IV) recovery are discussed. In contrast to silica, tiron is anchored to unmodified alumina. Germanium(IV) adsorption on the Al 2 O 3 –PHMG–tiron adsorbent is both due to interaction with tiron and due to interaction with the alumina surface, while on SiO 2 –PHMG–tiron, adsorption is solely due to complexation with the reagent followed by the formation of surface compounds of the Ge : tiron = 1 : 3 stoichiometry. Quantitative (99%) recovery of germanium(IV) by the SiO 2 –PHMG–tiron adsorbent is achieved in a pH range of 2.0–6.5, and by the Al 2 O 3 –PHMG–tiron adsorbent in the range from 0.5 M HCl to pH 8.5.

Functionalized adsorbents with poly-(4,9-dioxododecane-1,12-guanidine) (SiO2-PDDG) and mercaptophenyl groups (MPhS) were used for the separation of Se(VI) and Se(IV) for the first time. Fixation of PDDG was characterized by capillary electrophoresis and TGA/DSC. The quantitative extraction of Se(VI) proceeded due to anion exchange at pH 3-7. The adsorption capacity of SiO2-PDDG for Se(VI) was 28 μmol g-1. Silicas with mercaptophenyl groups were used for the extraction of Se(IV) from solutions in the range of 2 M HCl - pH 6.5. The adsorption capacity of MPhS was 35 μmol g-1. A system of columns containing synthesized adsorbents was proposed for the separation of Se(VI) and Se(IV) and their subsequent determination by ICP-MS. Optimal parameters of adsorption include a flow rate of 1 mL min-1, pH of 5, and sample volume of 200 mL. Se(IV) was desorbed with 5 mL of 0.25 M 2,3-dimercapto-1-propanesulphonic acid and Se(VI) with 5 mL of 1 M HNO3. The preconcentration factor was 40. The limits of detection (3s) were 0.75 and 1.25 ng L-1 for Se(VI) and Se(IV), respectively. The proposed method (SPE-ICPMS) was used to determine selenium species in natural water and certified reference materials. The separation was carried out directly at the sampling site.

The possibilities of utilization of technogenic products of aluminum production: coal foam and carbon concentrate (СС) are considered. It is proposed to utilize CC in order to extract valuable components. The regularities of the utilization process of CC by the combustion method have been studied. It was found that the content of germanium in ash is determined by the temperature and the oxygen partial pressure in the system. Gallium is concentrated in ash in an amount of 0.8 wt.% during the combustion in a fluidized bed at a temperature of 1200 °C, the germanium extraction into sublimates reaches 90 %. The results of the leaching of gallium from the ash residue in acidic and basic media are presented; the maximum gallium extraction was 90 and 94 %, respectively.

Silicas, sequentially modified with polyhexamethylene guanidine and 8-hydroxyquinoline‑5-sulfonic acid (SiO2-PHMG‑oxine) or 7-iodine‑8-hydroxyquinoline‑5-sulfonic acid (SiO2-PHMG‑ferron), have been proposed for the adsorption-luminescent determination of Y(III) in natural waters. Complex compounds of Y(III) are formed on the surface of adsorbents during adsorption from solutions at pH 6–7, which luminesce in a yellow-green color (λlum = 485 nm (SiO2-PHMG‑oxine) and λlum = 490 nm (SiO2-PHMG‑ferron)). This is the basis for the method of its sorption-luminescent determination. The detection limit of Y(III), calculated according to the 3s criterion, is 1 μg/L (SiO2-PHMG‑oxine) and 2 μg/L (SiO2-PHMG‑ferron), the analytical range is 4–400 μg/L (SiO2-PHMG‑oxine) and 6–500 μg/L (SiO2-PHMG‑ferron). The developed methods were tested in the determination of yttrium in the Yenisei and Kacha rivers of the Krasnoyarsk Krai

Silicas chemically modified with a number of sulfur-containing groups (mercaptopropyl, mercaptophenyl, dipropyl disulfide, thiadiazole thiol, dithiocarbamate and thiourea derivatives) were proposed for the separation and preconcentration of precious metals. These adsorbents quantitatively extracted precious metals from 0.5 to 4 M solutions of hydrochloric acid. It allowed their separation from high concentrations of non-ferrous, alkaline earth, alkali and some other related metals. The selectivity of separation of kinetically labile precious metal ions in ligand substitution reactions from kinetically inert ones depended on the nature of sulfur atom within the functional group of adsorbents and increased when passing from thione to thiol sulfur. Approaches for the preconcentration of precious metals using silicas chemically modified with sulfur-containing groups prior to their AAS, ICP-OES, and ICP-MS determination in ores, concentrates and their processing products were proposed. The correctness of the developed methods was confirmed by the analysis of certified reference materials.

Gallium and germanium are highly important elements used in different high-tech areas, and new secondary raw materials for its extraction are the subject of a thorough search. In this study, germanium is found in the wastes from the Hall-Heroult process for the first time. The mechanism of gallium and germanium circulation in the aluminum reduction cell is discussed. Four types of materials, namely carbon dust, flotation tailings, carbon concentrate, and ash, were examined. It was found that a temperature of 900 °C is sufficient for the complete combustion of the carbon concentrate. The gallium concentration in the ash may reach up to 4.0 kg/ton. The germanium extraction to sublimates reaches up to 90%. Carbon concentrate being the processing product of carbon dust from an aluminum reduction cell is a promising secondary raw material for germanium and gallium extraction.

Приведены результаты изучения состава биологически активных веществ водной фракции экстракта надземной части альфредии поникшей на 95 % этаноле, обладающей антиамнестическим действием. Исследования выполнены с использованием хроматографических и масс-спектрометрических методов анализа. Во фракции определено общее содержание азотсодержащих соединений — (10,63 ± 1,65) %. С применением аминокислотного анализатора выявлено наличие 15 аминокислот — (1,99 ± 0,11) %, из которых 7 аминокислот — (0,76 ± 0,012) %: лизин; треонин; валин; изолейцин; лейцин; фенилаланин; гистидин, оказались незаменимыми. Во фракции превалируют глутаминовая и аспарагиновая кислоты, валин, пролин, аланин и гистидин. В составе фракции обнаружено 43 элемента — (1,35 ± 0,1) %, из которых 19 — эссенциальные или условно эссенциальные. Доминирующими явились калий, магний, цинк, рубидий, фосфор, кальций и марганец. В составе фракции выявили преобладание углеводов (32 ± 3,1) %.

The composition of biologically active substances in the aqueous total fraction of the 95% EtOH extract of the aerial part of Alfredia cernua (L.) Cass. possessing antiamnesic properties was studied using chromatographic and mass-spectrometric methods. The total amount of N-containing compounds in the fraction was found to be 10.63 ± 1.65%. Fifteen amino acids (1.99 ± 0.11%), seven of which (0.76 ± 0.012%) were essential and included lysine, threonine, valine, isoleucine, leucine, phenylalanine, and histidine, were identified using an amino-acid analyzer. The total fraction was dominated by glutamic and aspartic acids, valine, proline, alanine, and histidine. The composition included a total of 43 elements (1.35 ± 0.1%), of which 19 were essential or conditionally essential. The predominant elements were K, Mg, Zn, Rb, P, Ca, and Mn. Carbohydrates dominated (32 ± 3.1%) the fraction.

ABSTRACT Novel silica-based adsorbent layer-by-layer modified with polyhexamethylene guanidine and 7-iodine-8-hydroxyquinoline-5-sulphonic acid (Ferron) was used for preconcentration and adsorption-fluorimetric determination of Zn(II). A simple and express method for adsorbent preparation is described in the present work. The prepared adsorbent extracts Zn(II) from solutions with pH of 5.0–7.0, with the formation of a luminescent complex λlum = 500 nm (λex = 380 nm) on the surface. An adsorption-fluorimetric method was developed for determination of Zn(II) in natural water using adsorbent sequentially modified with polyhexamethylene guanidine and Ferron; detection limit was 4 µg L−1. The procedure was used for the analysis of water from rivers and artesian wells of the Krasnoyarsk Krai (Russia).