scholarly journals Determination of phenolic compounds in medicinal preparations by galvanostatic coulometry

2021 ◽  
Vol 8 (1) ◽  
pp. 20218110
Author(s):  
N. N. Yaschenko ◽  
S. V. Zhitar ◽  
E. G. Zinovjeva
Keyword(s):  
Phenolic Compounds ◽  
Coulometric Titration ◽  
Experimental Studies ◽  
Coulometric Determination ◽  
Correct Definition ◽  
Galvanostatic Coulometry ◽  
Coulometric Method ◽  
Preliminary Separation ◽  
Ascorbic Acids

In this work, the possibility of using reactions of electrogenerated titrants with phenolic compounds was studied and a method for their coulometric determination in medicaments by galvanostatic coulometry was developed. The research objects were: rutin, salicylic acid and drugs containing phenolic compounds such as «Ascorutin», «Salicylic Paste» and «Salicylic Ointment» of Russian manufacture. Electrogenerated halogens (Cl2, Br2 and I2) and hexacyanoferrate(III)-ions were used as titrants. It was found that for the quantitative determination of phenolic acids, the optimal reagent is electrogenerated bromine, for rutin - electrogenerated bromine and iodine, and for ascorbic acid - any of the studied electrogenerated titrants (Cl2, Br2, I2 and [Fe(CN)6]3-). The correct definition was checked by the «entered-found» method, the error does not exceed 2%. As experimental studies have shown, our method of coulometric titration with electrogenated bromine and iodine is characterized by good reproducibility of results, expression, accuracy and can be used to determine phenolic compounds in drugs, for example, «Ascorutin» tablets. It should be noted that by our procedure it is possible to determine the spectrum of phenol-containing compounds (rutin, ascorbic and salicylic acids) in drugs without their preliminary separation. Therefore, the coulometric method using electrogenerated titrants can be recommended for the determination of salicylic, ascorbic acids and rutin in dosage forms. The proposed method is accurate and eliminates the experiment error in comparison with the Pharmacopoeic method.

The Coulometric Determination of Glucose in Human Serum

1968 ◽  
Vol 14 (5) ◽  
pp. 463-476 ◽  
Author(s):  
Robert K Simon ◽  
Gary D Christian ◽  
William C Purdy
Keyword(s):  
Human Serum ◽  
Glucose Oxidase ◽  
Coulometric Titration ◽  
Aerobic Oxidation ◽  
Enzymatic Reaction ◽  
Complete Recovery ◽  
Serum Levels ◽  
Normal Serum ◽  
Coulometric Determination

Abstract The coulometric titration method is combined with the use of an enzymatic analytic reagent for the determination of glucose in human serum. The glucose in 25 µl. of serum is determined in a protein-free filtrate (PFF) with an accuracy of ± 3% and a coefficient of variation of approximately 2%. The procedure routinely covers a concentration range of 25-250 mg/100 ml. Calibrations are linear to at least 450 mg./100 ml. with zero intercept. Glucose oxidase specifically catalyzes the aerobic oxidation of glucose to hydrogen peroxide. The peroxide reacts with iodide, in the presence of molybdenum (VI) catalyst, to form iodine. A known excess of thiosulfate reduces the iodine as it is produced. The reagents and the sample are incubated at 25.0° and pH 5.1. After 15 min., the pH is adjusted to 8.0 with phosphate reagent to stop the enzymatic reaction. The residual thiosulfate is titrated coulometrically with iodine at pH 8.0 to a dead-stop end point at a generating current of 0.4825 ma. The difference between the sample and thiosulfate reagent titers is proportional to the glucose concentration. The method is empirical. Peroxide-reducing impurities in the glucose oxidase preparation and mutarotation equilibrium prevent the complete recovery of glucose under the conditions of the experiment. Calibrations are reproducible from day to day and week to week. Reagents and the PFF constitute a negligible titration blank. Only 1 calculation is necessary. A simplified apparatus and procedure for the preparation of PFF’s permits 15 manual determinations per hour. Coulometric assays of commercial serum controls are accurate to within 3-4%. Data indicate that the precision of the coulometric method exceeds that of the Auto-Analyzer, Folin-Wu, Glucostat, and Nelson-Somogyi procedures. The proposed method is free from interferences at normal serum levels.

scholarly journals Determination of low chlorine content in organic compounds and polymers using an «Expert-006» coulometer

2018 ◽  
Vol 84 (7) ◽  
pp. 16-20
Author(s):  
D. Kh. Kitaeva ◽  
A. G. Buyanovskaya ◽  
O. A. Levinskaya ◽  
S. L. Dzvonkovski
Keyword(s):  
Coulometric Titration ◽  
Silver Ions ◽  
Electrolytic Cell ◽  
Chloride Ions ◽  
Chlorine Content ◽  
Residual Chlorine ◽  
Coulometric Determination ◽  
Electrochemical Parameters ◽  
Organic Matrices

A method of visual mercurimetric titration of chloride ions is widely used in elemental microanalysis for determination of chlorine content in organic substances after their combustion in an oxygen-filled flask. However, when chlorine content is less than 0.5%, the mercurimetric method fails to provide essential accuracy, and a more sensitive method of chlorine coulometric titration by electrogenerated silver ions appeared favorable. We consider a possibility of determining the microgram content of chloride-ions in solutions using a digital coulometric analyzer («Expert-006» produced by «Econics-Expert» (Moscow)) supplemented with an electrolytic cell with silver electrodes. The coulometer was tested in different operation modes to select the optimal electrochemical parameters of ion chloride titration and develop a technique for coulometric determination of chloride ions which in combination with the preliminary burning of the analyzed substances in an oxygen-filled flask provides determination of the residual chlorine in organic matrices at a level of 0.1 – 0.5%. The proposed technique was used to determine the residual chlorine in a number of polymers. The relative error did not exceed 5% at chlorine concentrations of 0.16 – 0.28%.

Coulometric Determination of Protein Nitrogen

1965 ◽  
Vol 11 (3) ◽  
pp. 413-421 ◽  
Author(s):  
Gary D Christian ◽  
Edward C Knoblock ◽  
William C Purdy
Keyword(s):  
Serum Samples ◽  
Coulometric Determination ◽  
Protein Nitrogen ◽  
Direct Titration ◽  
Coulometric Method ◽  
Kjeldahl Digestion

Abstract A coulometric method is described for the determination of ammonia resulting from micro-Kjeldahl digestion of protein samples. The method has been applied to the direct titration of the ammonia in the digests. Routine titration of the ammonia resulting from 10-µl. serum samples is described; the method has been applied to 1-µl. samples. Results are compared with standard macro- and micro-Kjeldahl procedures.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Energetic properties of peat saturated with petroleum products

2020 ◽  
Vol 13 (2) ◽  
pp. 105-109
Author(s):  
E. S. Dremicheva
Keyword(s):  
Crude Oil ◽  
Diesel Fuel ◽  
Energy Use ◽  
Experimental Studies ◽  
Calorific Value ◽  
Petroleum Products ◽  
Ash Content ◽  
Motor Oil ◽  
Initial Sample

This paper presents a method of sorption using peat for elimination of emergency spills of crude oil and petroleum products and the possibility of energy use of oil-saturated peat. The results of assessment of the sorbent capacity of peat are presented, with waste motor oil and diesel fuel chosen as petroleum products. Natural peat has been found to possess sorption properties in relation to petroleum products. The sorbent capacity of peat can be observed from the first minutes of contact with motor oil and diesel fuel, and significantly depends on their viscosity. For the evaluation of thermal properties of peat saturated with petroleum products, experimental studies have been conducted on determination of moisture and ash content of as-fired fuel. It is shown that adsorbed oil increases the moisture and ash content of peat in comparison with the initial sample. Therefore, when intended for energy use, peat saturated with petroleum products is to be subjected to additional drying. Simulation of net calorific value has been performed based on the calorific values of peat and petroleum products with different ratios of petroleum product content in peat and for a saturated peat sample. The obtained results are compared with those of experiments conducted in a calorimetric bomb and recalculated for net calorific value. A satisfactory discrepancy is obtained, which amounts to about 12%. Options have been considered providing for combustion of saturated peat as fuel (burnt per se and combined with a solid fuel) and processing it to produce liquid, gaseous and solid fuels. Peat can be used to solve environmental problems of elimination of emergency spills of crude oil and petroleum products and as an additional resource in solving the problem of finding affordable energy.

EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH CROSS-SHAPED SPATIAL CRACK UNDER TORSION WITH BENDING

2020 ◽  
Vol 92 (6) ◽  
pp. 13-25
Author(s):  
Vl.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.M. MIHAILOV ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Determination ◽  
Calculation Method ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Design Parameters ◽  
Reinforced Concrete Structures ◽  
Experimental Scheme

The article offers a method and program for experimental studies of reinforced concrete structures with cross-shaped spatial crack under torsion with bending, the main purpose of which is to check the design assumptions and experimental determination of the design parameters of the proposed calculation method. The conducted experimental studies provide an opportunity to test the proposed calculation apparatus and clarify the regularities for determining deflections, angles of rotation of extreme sections, and stresses in the compressed zone of concrete. For analysis, the article presents a typical experimental scheme for the formation and development of cracks in the form of a sweep, as well as characteristic graphs of the dependence of the angles of rotation of end sections.

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