Chemistry

ОПРЕДЕЛЕНИЕ КОФЕИНА И НЕКОТОРЫХ ПИЩЕВЫХ ДОБАВОК В ВИНАХ, ЭНЕРГЕТИЧЕСКИХ И ТОНИЗИРУЮЩИХ НАПИТКАХ

The method of capillary electrophoresis to determine the content of caffeine and food additives: ascorbic (E300), sorbic (E200), benzoic (E210) acids; sweeteners – saccharin sodium (E954), acesulfame potassium (E 950) in wines, energy drinks and tea. The comparative characteristic of the caffeine content, and the aforementioned food additives in beverages. A comparison with the corresponding regulations. It is shown that the concentration of benzoic acid in beverages above the maximum allowable concentration in beverages Flesh and MONETO.

Determination of the Main Substances in the Preparations of Cephalexin and Cefuroxime Axetil

Techniques of determination of the main substances in capsules of cephalexin and tablets of cefuroxime axetil have been elaborated. For separation of ancillary compounds, the two modes have been approbated, i.e. filtration and centrifugation. The advantage of the second means has been shown.

Phase Equilibria and Critical Phenomena in the Water–i-Butyric Acid Binary System

Phase equilibria and critical phenomena in the water-i-butyric acid binary system were studied by the visual polythermal method over the temperature range –10–30°C. The system is characterized by delamination with an upper critical solution temperature (UCST) equal 25.8°C. In the system at –1.8°C, these occurs a nonvariant monotectic equilibrium whose solid phase are ice crystals. The phase diagram of the system is plotted.

Quantum-chemical Evaluation of Thermal Stability of Some Lanthanide Complexes with Methoxybenzoate

Structural and energetic parameters of neodymium, europium, terbium and erbium complexes with 2- and 3-methoxybenzoic and 3,4-dimethoxybenzoic acids were studied. Correlation between Ln-O bond energy and temperatures of decomposition of studied compounds was found.

Multivariate Regression Methods for Simultaneous Сatalimetry Determination of Iridium (IV) and Rhodium (III)

Application of multivariate regression methods for catalimetry simultaneous determination of iridium (IV) and rhodium (III) based on oxidation of N-methyldiphenylamine-4-sulphonic acid by periodations in weak acid medium was investigated. The data structure of the kinetic measurement was studied with Principal Component Analysis, it was found that the distribution of the samples corresponds to an increase in the total concentration of the catalysts of the PC1 and change the concentration ratio Ir: Rh on PC2.

Quantum Chemical and Infrared Spectrometric Studies Sulfoderivatives Di- and Triphenylamines

The result of quantum-chemical studying of geometric characteristics for aromatic amine sulfoderivatives at MP2/6-31G(d,p) as well as experimental and theoretical investigation of IR spectra of these compounds are presented. It was shown for triphenylamine (TPhA) and triphenylamine-4-sulfonic acid (TPhASA) that theoretical vibrational spectrum was in good agreement with experimental data.

Reaggregation Positional Isomers Tetrazologeksahidroquinazoline

9-phenyl-4,5,6,7,8,9-geksagidrotetrazolo[5,1-b]quinazoline in solution undergoes reaggregation ent via an azide to form a positional isomer corner structure that is installed involving spectral methods (1H-NMR, IR -spectra), TLC, chromato-mass spectrometry.

Ethanol Conversion on Zeolites

The possibility of converting the biomass to products of petrochemical synthesis is shown. The analysis of the development of the synthesis of catalysts for production of motor fuels from bioethanol is carried out. By varying the composition of the catalysts and the process conditions can be synthesized gasoline range hydrocarbons, ethylene, aromatic hydrocarbons. A scheme for the conversion of ethanol to hydrocarbons of various classes is discussed.

Viscous Degradation of Acidic Chitosan Solutions and its Ionic Probe Study

A review of the literature on the phenomenon of aging (a significant drop in viscosity over time) of acidic chitosan solutions is given. A study was made on acetic acid (2%) solutions of chitosan of two viscosity-average molecular weights (200 and 46 kDa) by ion probing (addition of a KI solution). It has been indirectly confirmed that the motion of the probing ions in an electric field disturbs part (about a quarter) of the average macromolecule rather than the whole one.

Selective Determination of Histidine in Mixed Solutions of α-Amino Acids

Examined the condition of the main and neutral α-amino acids in aqueous media. Graphs of the distribution of ionized forms of histidine and alanine with varying pH. Pakistan the possibility of pH –metric selective determination of histidine in mixtures of neutral amino acid with a glass indicator electrode. The error does not exceed 7%

Pages