A review of publications on the creation and application of certified reference materials for the chemical analysis of geological materials and environmental objects with the aim to ensure the uniformity of measurements is presented.

Certified reference materials of geological and environmental objects: Problems and solutions

The process of supercritical fluid encapsulation of pharmaceutical grade risperidone into bioresorbable D,L-polylactide microparticles via the PGSS (Particles from Gas-Saturated Solutions) method was examined. Micronization and changes in the morphology of risperidone crystals during its encapsulation into a polymer plasticized with supercritical carbon dioxide were experimentally observed. This result made it possible to prepare the polymer structures of various dispersities (from 10 to 100 μm) and morphologies containing up to 40 wt % of risperidone without the use of organic solvents. The kinetics of release of risperidone from polymer microparticles in saline solution was studied by UV spectrophotometry. It was shown that the use of D,L-polylactides of various molecular weights makes it possible to achieve a controlled increase in the time of release of risperidone from bioresorbable polymer particles prepared via the PGSS technique up to ten days.

Supercritical fluid fabrication of components for a sustained-release injectable risperidone dose form

In this article the methodical aspects of quantitative elemental analysis of organic compounds on the automatic CHNS-analyzers, combining the method of Dumas-Pregl and gas chromatographic separation of analytic forms elements (N2, CO2, H2O, SO2) recorded by the thermal conductivity detector are explored. Also there are shown methods of calibration of the thermal conductivity detector, including the traditional way that uses one standard sample and the way that uses three standard samples with different quantitative content determined elements. Besides, attached the methodical approach, which is used in quantitative elemental analysis of organic compounds and their mixtures on the automatic CHNS-analyzers made on local and abroad plants, is based on operative control of calibration characteristics that we get from the thermal conductivity detector (characteristics and results of a standard sample of known composition before and after elemental analysis of unknown compound).

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Methodical aspects of quantitative elemental analysis of organic compounds using automated CHNS-analyzers

The current status of the determination of the purity of high-purity organic substances using direct and indirect chromatographic methods is discussed. It is shown that the results of the chromatographic determination of the main component in high-purity organic materials are generally ambiguous and unreliable. The possibility of determining the purity of organic compounds using an elemental analyzer of C, H, and N without involving standard samples of analytes is examined; the advantages and drawbacks of this approach are discussed. It is demonstrated experimentally by the example of several nitrogenated compounds that the main component can be determined with an error no worse than 0.6 rel. %, whereas the error of element (nitrogen) determination in the molecule does not exceed the permissible error of elemental analysis.

V. V. Kosenko

Papers

Determination of the main component in high-purity organic substances: Current status and prospects