Chemistry

Visual Colorimetric and Colorimetric Determination of Cefuroxime

Cefuroxime is a cephalosporin antibiotic with a wide spectrum of antibacterial activity for gram-positive and gram-negative microorganisms. It is in the list of vital and essential drugs for medical use. Currently, spectroscopic, chromatographic, electrochemical methods are used to determine cefuroxime. In current study we developed test agents in the form of indicator papers and powders with an immobilized Fehling reagent for the rapid determination of cefuroxime. Cellulose paper and silica gel were used as a solid matrix to create testing means.

The Research of the Behavior of Cefixime in Aquatic and Biological Media by Spectrophotometric Method

The research of behavior of cefixime in biological media was conducted by spectrophotometric method. It was shown that the maximum of light absorption of cefixime against the background of oral fluid is observed at λ = 292 nm and for blood serum at λ = 289 nm. The interval of linear dependence optical density – concentration of cefixime is 3–50 mkg/ml. The optimal conditions of precipitation of proteins in the studied biological media were revealed.

The Synthesis of New Organoselenium Heterocyclic Compounds: 2,4-Diaryl-5,6,7,8-Tetrahydroselenochromilium’s Salts

The synthesis of novel organoselenium heterocyclic compounds is of great theoretical and practical interest because of high biological activity. The known methods of synthesis of hexatomic selenium containing heterocyclic compounds allow us to obtain only monoaryl-substituted tetrahydroselenochromilium salts. In this study, the reactions of 2-(3-oxo-1-aryl-3-phenylpropyl) cyclohexanones were carried out with hydrogen selenide in situ under conditions of acid catalysis in diethyl ether.

Researching the Oxidation Process of Sulfur-Alkalaine Sewage Components Using Ni2+ Catalyst – Containing Galvanic Wastewater

The effect of different concentrations of nickel (II) ions on the oxidation rate of mixed wastewater pollutants with ozone-air mixture for 30 minutes with an ozone concentration of 3 mg/l was studied. It was shown that adding nickel (II) ions at a concentration of 300 mg/l reaches the maximum degree purification of wastewater as a result of oxidative processes on the COD value, equal to 40.4%, which is 10.1% more compared to the catalytic oxidation of the investigated wastewater pollutants with the air oxygen participation.

Extractive Crystallization of Salt and Phase Equilibria in the Ternary System Sodium Nitrate – Water – Dipropylamine

Phase equilibria in the ternary system sodium nitrate – water – dipropylamine where the constituent binary liquid system is characterized by a trend to form a lower critical solution temperature (LCST) were studied using the visual-polythermal method in the range −10.0–90.0° C. It was found that the introduction of sodium nitrate into the water – dipropylamine system led to a significant decrease in the mutual solubility of the components.

Comparison of Cytotoxic Activity of Compounds from the Benzimidazolequinazoline and Pyridopyrimidine Series

Colorimetrically using the MTT assay the cytotoxic activity of 5-aryl-1,2,3,4,5,6-hexahydrobenz[4,5]imidazolo[1,2-a]quinazolines and a tautomeric mixture of 4-amino-2-phenyl-6H-pyrido[1,2-a] pyrimidin-3-carbonitrile with 2-(phenyl(pyridin-2-ylamino)methyl)- malononitrile was screened. These compounds were obtained by the three-component condensation of aromatic aldehydes (benzaldehyde, 3-bromobenzaldehyde, 4-methoxybenzaldehyde), heterocyclic amines (2-aminobenzimidazole or 2-aminopyridine) and cyclohexanone or malonic acid dinitrile in comparison with the starting amines.

Chemometric Algorithms for the Monitoring of Milk Quality by Potentiometric Titration

The acute problem in the analysis of dairy products is the potentiometric determination of the active and total titrated acidity of pasteurized milk from different manufacturers and their comparison with those for raw cow milk. In addition, for various expert purposes, fast definition of the manufacturer of this product is necessary. The conditions of potentiometric titration of pasteurized milk are specified. It is shown that the total acidity of pasteurized milk produced by different manufacturers differs insignificantly.

Extraction-Photometric Determination of Cobalt (II) with Hydroxytiophenols and Hydrophobic Amines

The possibility of using hydroxythiophenols (HTP) for the photometric determination of cobalt (II) has been studied. Aminophenols (AP) were used as hydrophobic amine: 2- (N,N-methylamino methyl)-phenol (AP1) and 2- (N, N-methylaminomethyl) -4-methylphenol (AP2). Dichloroethane, chloroform and carbon tetrachloride turned out to be the best extractants. With a single extraction with chloroform, 97.5–99.5% of cobalt is recovered as a complex. The cobalt (II) complex is extracted into chloroform in the pH range of 3.6–6.3.

The Effect of Surfactant Micelles on the Fluorescent Properties of a Complex of Yttrium with Levofloxacin

The effect of complexation with yttrium ions and micellar media of surfactants on the fluorescent properties of levofloxacin was studied. The luminescence of levofloxacin depends on the acidity of the medium Т. Г. Данилина и др. Влияние мицелл поверхностно-активных веществ 378 Научный отдел Изв. Сарат. ун-та. Нов. сер. Сер. Химия. Биология. Экология. 2019. Т. 19, вып. 4 and is maximum in an acidic medium. It was shown that complexation with yttrium ions promotes the growth of the intrinsic fluorescence of levofloxacin by a factor of 2.

Data Approximation for Plotting the Binodal Curve on the Phase Diagrams of Some Ternary Salt – Water – Isopropyl (n-Propyl) Alcohol Systems

A brief review of computational methods for the liquid-liquid equilibrium has been carried out, and their capabilities and limitations have been shown. Complications of such computational models for the liquid–liquid–solid equilibrium lead to a decreased accuracy of calculations. In this case, it is advisable for researchers to make use of the approximation of experimental data on the liquid – liquid and liquid – liquid – solid equilibria.

Pages