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This review is devoted to the consideration of prospects and directions for the development of methods and approaches to the analysis of high-purity industrial gases and volatile hydrides, chlorides, fluorides, and organoelement compounds with natural and isotopically enriched compositions. The currently known capabilities for the determination of impurities in them using mass spectrometry, IR spectroscopy, gas chromatography, and chromatography-mass spectrometry are analyzed., Author(s): A. Yu. Sozin [sup.1] , V. A. Krylov [sup.2] , O. Yu. Chernova [sup.1] , T. G. Sorochkina [sup.1] , A. D. Bulanov [sup.1] , A. P. Kotkov [sup.3] [...]

Background: Today, biologically active additives, which contain hydrolytic enzymes (amylase, lipase, protease), are widely used in the digestive industry. These enzymes are often obtained from animal and vegetable raw materials, -for example, from the pancreas of a reindeer, the Fabricius bag of chickens, and Medusomyces Gisevii Lindau (Kombucha). However, in obtaining enzymes, the activity of amylase and lipase may decrease due to active forms --of proteases. Objective: The main goal of this research work was to evaluate the stabilizing effect of nanostructures-cyclodextrins on the activity of hydrolytic enzymes (protease, amylase, lipase) obtained from animal raw material (chicken bursa of Fabricius) and microorganism cultures (Kombucha). Identify the relationship at which the negative influence of external environmental factors is leveled and, as a result, enzymatic activity is maintained for a certain period of time. Methods: The protein concentration in the solution was determined using the Lowry method. A modified method by Rukhlyadiva was used to determine the amylolytic activity. The definition of lipolytic activity is based on modified Shibabi-Bishop method. To determine the amylolytic activity, a modified method by Rukhlyadiva was used. Results: The relationship between b-cyclodextrin and enzymes was determined, at which enzymatic activity is maintained for a certain period. Conclusion: Thus, cyclodextrins in solution stabilizes the activity of proteases, amylases, and lipases, which is of great practical importance in the food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

The impurity composition of natural and isotopically enriched silane obtained from magnesium silicide and silicon tetrafluoride is studied by gas chromatography-mass-spectrometry. The impurities characteristic of silane with natural and isotopically enriched composition are atmospheric gases; carbon dioxide; hydrides; saturated, unsaturated, and aromatic hydrocarbons; halogenated hydrocarbons; alkyl derivatives and silane homologues, siloxanes. The impurity content of high-purity silane does not exceed 10.sup.-7-10.sup.-5 mol % After synthesis, the concentrations of impurities in the silane and fractions isolated by its distillation purification lie in the range n x 10.sup.-6 - n x 10 mol % The limits of detection for impurities are 1 x 10.sup.-8-9 x 10.sup.-4 mol %, Author(s): A. Yu. Sozin [sup.1], V. A. Krylov [sup.2], O. Yu. Chernova [sup.1], T. G. Sorochkina [sup.1], A. D. Bulanov [sup.1], O. Yu. Troshin [sup.1], A. P. Kotkov [sup.3], N. [...]

A silica fiber preform with a reflective cladding and 28SiO2-based isotopically enriched core has been produced by modified chemical vapor deposition (MCVD) using high-purity 28Si-enriched silicon tetrachloride. We have measured the refractive index profile across the preform. Using secondary ion mass spectrometry, we have obtained distribution profiles of the silicon isotopes across the preform. The 28Si content of the silicon in the core has been determined to be at a level of 99.9%. The preform has been drawn into fiber with a reflective cladding and a 28SiO2-based isotopically enriched core. The optical loss in the fiber at wavelengths from 900 to 1750 nm has been determined to be 1–2 dB/km. We have measured the radiation-induced loss in the silica fiber with the 28SiO2 isotopically enriched core at a gamma dose rate of 3.2 Gy/s and wavelengths of 1.31 and 1.55 μm. [ABSTRACT FROM AUTHOR]

The impurity composition of isotopically enriched germane 70GeH4 was studied for the first time by gas chromatography–mass spectrometry. Impurities were separated using capillary adsorption columns: GS-GasPro (60 m × 0.32 mm) packed with silica gel, GS-CarbonPLOT (25 m × 0.32 mm × 0.25 μm) packed with a carbon sorbent, and a column packed with poly(trimethylsilylpropyne) (25 m × 0.26 mm, df = 0.25 μm)). The use of these columns is shown to provide a high resolution of chromatographed substances. Impurities were identified by comparing their mass spectra with the data of the NIST library. Gases forming a part of the atmosphere, C1–C7 hydrocarbons, chlorine- and oxygen-containing hydrocarbons, sulfur-containing substances, and homologs and alkyl derivatives of germane were detected in germane. As a result of studying the composition of their mass spectra, the mass spectra of impurities 70GeC3H10 and 70GeC4H12, which are absent in the published sources, were obtained and described for the first time. The concentrations of impurities in high-purity germane, as well as their distribution over fractions isolated during the rectification purification of germane, were determined. The limits of detection of the identified substances were 2 ×10–7–1 × 10–4 mol %. [ABSTRACT FROM AUTHOR]