Possibilities and issues of current analytical chemistry of inorganic materials

Russian Chemical Bulletin - In the present article, the state of the art of analytical chemistry of inorganic materials is considered. The role of such analytical methods as atomic-emission...     

Methodology and procedure of the stoichiographic analysis of solid inorganic substances and materials

The technical and experimental aspects of creating the conditions of differential dissolution in a flow stoichiographic system are discussed; the scheme of the experimental apparatus, stoichiograph, is presented. The construction, operation conditions of the main units of the stoichiograph, and sample treatment issues are considered. The principles of the creation and optimization of the conditions of the dynamic differential dissolution for the analysis of compounds and materials of the known and unknown phase composition are discussed: the composition of solvents and temperature, and the principles of their variation in time, including those in the processes of stoichiographic titration.     

无机硫氧化合物的分析化学

介绍滴定分析和仪器分析对无机硫氧化合物水溶液的定量分离分析。滴定分析一般只能定量S^2-,S^2-2,SO^2-3,S2O^2-4,S2O^2-3,SxO^2-6等离子中的一种或多种的总量,仪器分析则对多种离子混合物的分离和定量非常有效。     

Determination of chemical composition of solid inorganic substances and materials using the principles of stoichiography and voltammetry

The state of the art in determination of the phase composition of complex inorganic solids by chemical and electrochemical methods is discussed. The theoretical and practical essentials of stoichiography and the new stoichiographic method of differential dissolution (DD) are reported. The unique feature of this method is that reference samples of the analyzed solid phases are not necessary. The development of this stoichiographic method was strongly affected by voltammetry. The application of the DD method for determining the chemical composition of various substances and materials is presented. The complementary use of voltammetry and DD for the detection, identification, and quantitative determination of inhomogeneity of the chemical composition of high-temperature superconductors was shown to be efficient.     

Stoichiography and fanlike separation of substances in dynamic mass-transfer processes

For the first time, the concept of fanlike separation of substances in dynamic processes of homo- and heterophase mass transfer was introduced, which enables one to quantitatively determine the composi tions of mixtures of chemical compounds by stoichiographic calculations without selective separation of the mixtures.     

The role of reference materials in analytical chemistry

The paper demonstrates a concept and possible models for an international infrastructure of chemical measurements by using reference materials.The function of reference materials to establish traceability and means of quality assurance is emphasized.     

强化无机及分析化学实验室管理工作的实践

介绍了南京林业大学化学基础教学实验中心无机及分析化学实验室强化管理工作的若干经验。实践表明,实验室的管理逐步走向了规范化、科学化,有利于更好地服务于实验教学,顺利完成各项实验教学任务。     

A framework for the application and materials in analytical chemistry

 Working group 5 of EuraChem Nederland has developed a framework for the implementation of reference materials in analytical chemistry. In this discussed paper, the framework is proposed as a tool for the development of standard operation procedures (SOPs) in laboratories. The implementation of (certified) reference materials in these SOPs is of major importance in establishing comparability and traceability in measurement results, which in turn play a crucial role in measurement in support of trade, environmental issues, and characterisation of materials. Recent developments in the field of uncertainty analysis require the application of reference materials. It is recognised that the calculation of the combined measurement uncertainty becomes almost impossible without the use of certified reference materials with a stated uncertainty. Received: 1 December 1995 Accepted: 20 December 1995     

Supercritical fluid extraction of organic and inorganic mercury from solid materials

Mercuric ions (Hg(2+)) can be extracted from solid samples (cellulose matrix) using methanol modified supercritical CO(2) containing the fluorinated chelating agent lithium bis(trifluoroethyl)dithiocarbamate (LiFDDC). Methylmercuric chloride (CH(3)HgCl) and dimethylmercury [(CH(3))(2)Hg] can be extracted by supercritical CO(2) without chelating agent and modifier. The solubility of Hg(FDDC)(2) in supercritical CO(2) has been determined to be 5 x 10(-3)M at 5O degrees C and 150 atm, which is about 3 orders of magnitude greater than that of the non-fluorinated analogue Hg(DDC)(2). Use of methanol (5%)-modified CO(2) further enhances the solubility of Hg(FDDC)(2) by a factor of 2.4. A small amount of water added to the sample matrix tends to facilitate the extraction of Hg(FDDC)(2) and CH(3)HgCl. Potential applications of this in situ chelation-supercritical fluid extraction method for the preconcentration of mercury species and treatment of mercury contaminated wastes are discussed.     

Machine-enabled inverse design of inorganic solid materials: promises and challenges

Developing high-performance advanced materials requires a deeper insight and search into the chemical space. Until recently, exploration of materials space using chemical intuitions built upon existing materials has been the general strategy, but this direct design approach is often time and resource consuming and poses a significant bottleneck to solve the materials challenges of future sustainability in a timely manner. To accelerate this conventional design process, inverse design, which outputs materials with pre-defined target properties, has emerged as a significant materials informatics platform in recent years by leveraging hidden knowledge obtained from materials data. Here, we summarize the latest progress in machine-enabled inverse materials design categorized into three strategies: high-throughput virtual screening, global optimization, and generative models. We analyze challenges for each approach and discuss gaps to be bridged for further accelerated and rational data-driven materials design.

The grand challenge of materials science, discovery of novel materials with target properties, can be greatly accelerated by machine-learned inverse design strategies.     

Stoichiography for investigation of the functional materials composition,structure, and properties

Principles of the stoichiography and differential dissolution method (DD) providing deep insight into the composition of mixtures containing unknown chemical compounds are considered. Compounds can be identified using their primary feature — the stoichiometry of elemental composition; reference samples of the compounds are not needed. The DD method makes it possible to analyze mixtures of crystalline and/or amorphous phases with constant and/or variable composition in the form of dispersed powders, ceramics, crystals, thin films and nanosize objects. Various aspects of the stoichiography and DD method application to investigation of composition, structure and properties of the functional materials are discussed.     

Computer aided conversion of repeatability into trueness as applied to inorganic analytical chemistry

Based on the accepted definition of accuracy in analytical chemistry the distinction between accuracy and trueness is discussed and the superiority of trueness to accuracy in the hierarchy of terms is stressed.An updated model describing trueness of an analytical result is proposed and the process of analytical recognition is also considered. This model allows for determination of trueness from the repeatability of the method when applied under well defined working conditions, and thereby complies with the legal criteria of quality assurance. A strict division of analytical working methods is made:

The three-dimensional structure of humic substances and soil organic matter studied by computational analytical chemistry

A novel three-dimensional structural concept for humic substances and soil organic matter (SOM) is proposed which is based on previously published, comprehensive investigations combining geochemical, wetchemical, biochemical, spectroscopic, agricultural and ecological data with analytical pyrolysis. Direct, temperature-programmed pyrolysis in the ion-source of the mass spectrometer and soft ionization in very high electric fields (Py-FIMS) and Curie-point pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) were the main applied thermal methods. Emphasis is laid on molecular modelling and geometry optimization of complex, polydisperse structures of biomacromolecules using modern PC software (HyperChem^®). Trapping and binding of atrazine in an organo-mineral complex is introduced as a first example of simulation experiments for soil processes at atomic level (nanochemistry). Future applications of semi-empirical calculations and molecular dynamics in pyrolysis studies are outlined.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday     

Kurnakov and analytical chemistry

The paper appreciates the role of Academician N.S. Kurnakov in holding the All-Union Conference on Analytical Chemistry (1939) and creating the Commission on Analytical Chemistry at the Academy of Sciences of the USSR. The scientific works of Kurnakov relating to chemical analysis are indicated; brief review is given to studies on analytical chemistry that were carried out in the collectives headed by Kurnakov are.     

Traceability and analytical chemistry

 The basic concepts of traceability as they are defined by the Comité Consultatif pour la Cluantité de Matière are contrasted with the practical exploitation in chemical analysis. The applicability of traceability concepts are tested for their practical applicability on four different analytical methodologies, neutron activation analysis, plasma mass spectrometry, beam microscopical analysis and speciation analysis of organometallic compounds. Received: 31 March 1998 · Accepted: 6 June 1998