High-purity Substances Research Articles

Analytical methods in technological and environmental studies

The possibilities of modern analytical techniques to solve control problems in high-technology and environmental studies are considered. The first part of the article provides a review of the key concepts of the analytica. The second part is devoted to the problems associated with the analytical software technologies for high-purity substances and evaluation of the detection limits of elements by atomic spectrometry methods. The final part describes the analytical methods used in environmental monitoring. The main attention is paid to the studies that have been intensively conducted at the Research Institute of Chemical Reagents and Special Purity Chemical Substances, starting with 1970s. The institute has preserved traditional approaches and comprehensive research programs until present, even though the range of research topics is not so wide and the problems to be solved are not so ambitious.

Cybernetic researches in technology of chemical reagents and high-purity substances

Works in the area of the cybernetic researches in technology of the chemical reagents and high-purity substances (HPS) were carried out in the following four directions: system analysis in technology of HPS and synthesis of the optimal individual and flexible multi-assortment manufacturings; modeling and optimization of processes for the production of chemical reagents and HPS; creation of automated systems of scientific researches and control systems for the technological processes; development of the automated databases, expert systems of the artificial intelligence, and computer decision-making systems. During the development of strategy of the development of the chemical industry information technologies for the system analysis and rating estimation of innovative potential of 83 leading joint-stock and state ownership, R&D organizations were developed for the Ministry of industry of Russia. Also the system analysis of the innovation resources of the 165 leading industrial enterprises of chemical and petrochemical complex was carried out.

Glass formation and the third harmonic generation of Cu2Se–GeSe2–As2Se3 glasses

We have performed the investigation of the nonlinear optical properties namely the third harmonic generation (THG) of the glass-formation region in the Cu2Se–GeSe2–As2Se3 system. The samples were synthesized by direct single-temperature method from high-purity elementary substances. We have found that the value of disorder parameter Δ depends on the composition of the glassy alloys. The measurements show that increasing the Cu2Se concentration leads to increased slope of the absorption edge, which may be explained by the decrease of the height of random potential relief for the electrons in the tails of the state density which border the band edges. A very sharp increase in the THG at low temperature was observed. Significant enhancement in THG was obtained with decreasing the energy gap, which agreed well with the nonlinear optical susceptibilities obtained from other glasses.

Physicochemical principles underlying the preparation of high-purity substances for microelectronic and optical applications

This paper presents results on liquid-vapor, solid-vapor, liquid-liquid, and crystal-melt equilibria in solvent-solute systems. The data provide a physicochemical basis for the development of processes for the ultrapurification of volatile compounds of group II to VI elements (halides, hydrides, metalorganic compounds, and elemental substances).

Quasi-Adiabatic Investigations of Lead in Indium

The use of melting or freezing temperatures of high-purity substances as thermometric fixed points requires a knowledge of the binary phase diagrams of these substances and remaining impurities at very small impurity concentrations. In this paper, a calorimetric apparatus for the measurement of the change in liquidus temperature of fixed-point metals due to dissolved impurities at quasi-adiabatic conditions is presented. This approach combines advantages of the fixed-point method and adiabatic calorimetry. It is more efficient for the screening of a range of impurity concentrations than a fixed-point cell, requires less constructional and experimental expenditure compared with an adiabatic calorimeter, but provides similar small uncertainties on the millikelvin level. Measurements were carried out to determine the influence of lead on the melting temperature of indium at mass fractions up to 6.93 %. The results are in very good agreement with previous measurements by means of slim fixed-point cells in the Physikalisch-Technische Bundesanstalt and confirm a minimum of the freezing point of \(-\)178 mK at a mass fraction of about 3.7 %. It was demonstrated that this setup allows the investigation of binary phase diagrams with uncertainties less than 8 mK.

Do all organic chemists deal with high-purity substances?

High-precision data of C, H, N elemental analysis published in journals for any synthesized organic compound are not always true. Such precise results can be obtained only for high-purity organic compounds (purity degree of >99%). However, in determination of the purity of high-purity organic compounds, in particular, pharmaceutical substances and drugs, elemental analysis is either superior or equivalent to the generally accepted methods as it is versatile, fast, and does not require the use of standard analyte samples.

Reference Materials as a Crucial Tools for Validation and Verification of the Analytical Process

Traceability in analytical measurements is a key issue to ensure all measurement results are accurate, comparable and the products are safe for consumption. Therefore, validity of measurements can be assured when reference materials (RMs) are used to calibrate the equipments before the test report can be published. The role of reference materials in analytical process is outlined with specific example on high purity substances and validation process involved in quality assurance (QA). The main tasks of National Metrology Laboratory, SIRIM Berhad (NML-SIRIM) are reviewed including to ensure all measurement results are traceable to the international system of unit (SI), setting up the national primary standards and participating in international comparison organized by International Bureau of Weight and Measures (BIPM). Several advantages and crucial aspects for the validation of high purity organic RMs using quantitative nuclear magnetic resonance (qNMR) are discussed and illustrated by recent example for detection of lard in animal fats.

Development of CALS-technology for tetrachloromethane of reagent qualification and high purity

CALS concept became a base for development of the system for production of tetrachloromethane of various qualifications. The paper shows the structure of the database and interconnection of its components in addition to the chosen subject area - “High purity substances”. The authors considered development of the process regulation for tetrachloromethane by the means of CALS-system.

Assessment of interlaboratory and between-method discrepancies in composition certification of high-purity solid elemental substances and nanomaterials

We have assessed interlaboratory and between-method discrepancies in the certification of standards of high-purity nanomaterials and precursors and analyzed the dependence of the discrepancy on the impurity concentration (an important factor, influencing the discrepancy value) and analytical method.

Микроэкстракционное концентрирование примесей из воды с ультразвуковым диспергированием экстрагента

Microextraction preconcentration of impurities with ultrasonic dispersion of extractant exceeds in efficiency drop microextraction and microextraction with dispersion on auxiliary component. Capillary gathering of an extractant simplifies its selection and eliminates the losses of an extract connected with its evaporation. Limits of detection of esters of о - phthalic acid are 10 -5 -10 -6 mg/l which are not conceding to the best world results are reached. Key words: Microextraction concentration, ultrasonic dispersion, capillary gathering of a extraction solvent, detection limits (Russian) DOI: http://dx.doi.org/10.15826/analitika.2013.17.1.011 V.A. Krylov 1,2 , V.V. Volkova 1 , O.A. Saveleva 1 1 N.I. Lobachevsky Nizhny Novgorod State University, Nizhny Novgorod, Russian Federation 2 G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences , Nizhny Novgorod, Russian Federation

Хромато-масс-спектрометрическое определение примесей в фосфине высокой чистоты с использованием капиллярных адсорбционных хроматографических колонок

A possibility of the use of capillary adsorption columns in combination with mass-spectrometric detection was investigated with the aim to determine the content of impurities in high-purity phosphine. The effect of the volume of the main substance on separation and determination of impurities was studied. This effect mostly manifests itself with respect to impurities closely located to the front of phosphine. During the change of pressure of the introduced phosphine from 0.1 to 1 atm. the relative retention time of carbon dioxide decreases by 1-5 %. In case of impurity compounds with the retention factor not more than 0.5 the retention time does not depend on the volume of the introduced phosphine. The effect of displacement of impurities is accompanied by the increase in efficiency of a column. In substances eluting after phosphine, e.g., arsine, at pressure input of a sample more than 0.1 atm. there is almost a 10 times decrease is observed in efficiency of the column. The limits of detection of substances of 5∙10 -8 -1∙10 -5 vol. % were attained. They are the best values among those available in literature and for some impurities they by 2-1000 times lower. The content of 35 impurities was detected using the calibrating dependencies and estimates of sensitivity on the values of the total ionization cross sections of the determined substances. The content of impurities was determined in the samples of purified phosphine and in the fractions extracted from the top and the bottom part of rectification column. It was found that carbon dioxide, arsine and propylene are the mostly hard-to-remove impurities. Keywords: phosphine, impurities, gas chromatography–mass spectrometry, adsorption capillary columns, detection limit, trueness (Russian) DOI: http://dx.doi.org/10.15826/analitika.2013.17.4.011 V.A. Krylov 1,2 . O.Iu. Chernova 1 , A.Iu. Sozin 1 , A.P. Kotkov 1,3 , G.V. Pushkarev 2,3 1 G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, Russia, Nizhny Novgorod 2 N.I. Lobachevsky Nizhny Novgorod State University, Russia, Nizhny Novgorod 3 FGUP NPP “Saljut”, Russia , Nizhny Novgorod

Expert system for analytical monitoring of high purity organic solvents

The authors developed an expert system for selection the analytical equipment and method of analysis of high purity substances (by the example of the assortment of organic solvents). Knowledge bases are developed on the basis of information CALS-technologies and structured by application spheres, analyzed substances, indicators of quality, methods of analysis and analytic devices. In its turn, the knowledge base on the analytical devices is structured in 4 main clusters of quality indicators: the content of the base substance, metal cations, anions and suspended particles.

Supercritical fluid chromatography and its application to analysis and preparation of high-purity compounds

The principles of supercritical fluid chromatography (SFC) and its application in various fields are reviewed. A comparison of high-performance liquid chromatography (HPLC) and SFC is performed. In discussing the applications, emphasis is placed on the possibility of using SFC in analysis of impurities in pharmaceuticals and biologically important substances and in preparation of high-purity substances. In describing detectors for SFC, special attention is paid to mass-spectrometric detectors.

Synthesis of high-purity lower silicon alcoholates for new technology

Purification of a number of silicon derivatives (chloride, lower alcoholates) formed in processing of high-purity silicon for electronic and electrical industries was considered. It was found that high-purity substances suitable for use in electronics and optics can be produced from industrial wastes.

Supercritical Extraction from Vinification Residues: Fatty Acids,α-Tocopherol, and Phenolic Compounds in the Oil Seeds from Different Varieties of Grape

Supercritical fluid extraction has been widely employed in the extraction of high purity substances. In this study, we used the technology to obtain oil from seeds from a variety of grapes, from vinification residues generated in the Southern region of the state of Rio Grande do Sul, Brazil. This work encompasses three varieties of Vitis vinifera (Moscato Giallo, Merlot, and Cabernet Sauvignon) and two of Vitis labrusca (Bordô e Isabel), harvested in 2005 and 2006. We obtained the highest oil content from Bordô (15.40%) in 2005 and from Merlot (14.66%), 2006. The biggest concentration of palmitic, stearic, and linoleic acids was observed in Bordô, 2005, and in Bordô, Merlot, and Moscato Giallo, 2006. Bordô showed the highest concentration of oleic acid and α-tocopherol in both seasons too. For the equivalent of procyanidins, we did not notice significant difference among the varieties from the 2005 harvest. In 2006, both varieties Isabel and Cabernet Sauvignon showed a value slightly lower than the other varieties. The concentration of total phenolics was higher in Bordô and Cabernet Sauvignon. The presence of these substances is related to several important pharmacological properties and might be an alternative to conventional processes to obtain these bioactives.

Metrological aspects of development and certification of chemical analysis methods and accreditation of the analytical laboratory within the Giredmet Institute

The main requirements laid down in domestic and overseas standard documents for metrological provision of the activity of analytical laboratories are demonstrated on the example of the Giredmet analytical service. A comprehensive approach is considered for organizing the analytical service activity using a laboratory information management system and its role in metrological provisions. Results are summarized for modernization of a set of chemical analysis procedures for nonferrous, rare, and precious metals, high purity substances based upon them, nanomaterials, and semiconductors.

Standard reference materials of high-purity substances for metrological support of analytical monitoring of nanomaterials and their high-purity precursors

We consider aspects involved in preparation of chemical composition standard reference materials (SRMs) for nanomaterials. We show that the primary requirement for metrological support of analytical measurements is the availability of SRMs with certified chemical purity. We describe a procedure for preparation and certification of 40 such SRMs based on the Exhibition Collection of High-Purity Substances of the Russian Academy of Sciences. We describe modern methods for analysis of high-purity substances and nanomaterials based on them. We discuss problems involved in application of SRMs in nanoanalysis.

Mass-spectrometric elemental analysis of solid substances in Russia

The review surveys the achievements of Russian scientists in mass-spectrometric analysis made in the past decade. Attention is focused on direct and indirect methods for the elemental analysis of solid and powdered materials. Among them are mass-spectrometric elemental analysis techniques with spark, laser, glow discharge, and inductively coupled plasma ionization. The applications of the above techniques to various areas of science, technology, and industry are described, in particular, the elemental analysis of nuclear technology materials, the determination of trace impurities in high-purity substances, some applications in medicine, biology, ecology, and basic research. Some achievements in the mass-spectrometric technique for the determination of the elemental composition of solid and powdered materials are considered. Some characteristics of methods are given: the range of the analyzed elements, errors in the determination of concentrations, and the limit of detection.

Preparation of spherical activated carbon from furfural, its properties and prospective applications in medicine and the national economy

The peculiarities of the porous structure and adsorption properties of an extraordinarily high-strength ashless carbon adsorbent composed of spherical particles produced from synthetic furfural according to a principally new technique are considered. The adsorbents are shown to have a developed structure of sorbing micro- and mesopores and are characterized by increased hydrophobicity. The adsorbents are promising materials in the high-performance adsorption recuperation of organic solvents, in preparing high-purity substances, in purifying gaseous discharge, and in a number of other processes, especially under severe operation conditions, such as the adsorption in flowing and liquefied layers at a heightened moisture content in the gas flow. Furthermore, the high chemical purity, high adsorptivity with respect to substances with diverse physicochemical properties, and high mechanical strength of the adsorbents, as well as the smooth and antimisting surfaces of their grains, make them promising compounds for hemo- and enterosorption in detoxification of a living organism in case of diverse poisoning or disease.

A comparative uncertainty study of the purity assessment of chemical reference substances using differential scanning calorimetry (DSC) and mass balance method

This study introduces the general method of differential scanning calorimetry (DSC) for the purity assessment of chemical reference substances (CRSs). Thirty high-purity chemical reference substances were calibrated by the DSC method and the uncertainty of the measurements was calculated. The DSC method provided comparable CRS purity and uncertainty results to the method based on principle of mass balance (mass balance method). Therefore, the DSC method can be used for the purity assessment of suitable CRS. Purity determination by DSC has the advantage of practicality, speed, reproducibility, no corresponding reference standard requirement and no sample preparation is required. The DSC method is complementary to the mass balance method for the assay of chemical reference substances.