PubMed Health⌕ Search

Biomedical subjects

V B Korchagin

Publications and source records attributed to V B Korchagin.

18 recordsLinked to original sources
PubMed1979

[Determination of a dimethylaniline mixture in the intermediate products for the production of semisynthetic penicillins].

A gas-chromatographic method for determination fo the content of dimethylaniline (DMA) in 6-aminopenicillanic acid, a semi-product for production of semi-synthetic antibiotics, was elaborated. The chloroform extracts of DMA from the alkaline solutions of the preparation were analysed in a gas chromatograph with a flame-ionization detector on a stainless steel column 2 m long and the inner diameter of 2 mm filled with 10 per cent OV-17 on chromosorb W-HMDS at a temperature of 112 degrees C. The minimum detectable amount of DMA was 5.10(-9) g. The assay error was +/- 5.35 per cent. The method may be used for the assay of other semi-synthetic antibiotics.

Aniline Compounds↗
PubMed1978

[Use of the penicillanic acid formation reaction for the analysis of penicillins. The quantitative determination of oxacillin].

A procedure for quantitative determination of oxacillin by means of spectrophotometry is described. The procedure is based on the capacity of penicillins to transform on heating in acid buffer solutions containing copper ions into respective penicillenic acids having specific absorption characteristics in the UV-spectrum region. The amount of oxacillin was estimated by the optical density of the solutions at a wave length of 335 nm corresponding to the absorption maximum of the penicillenic acid of oxacillin. The optimal conditions for the reaction of the penicillenic acid formation, i.e. pH of the buffer solution and the level of the copper ions in it, time and temperature of heating were determined. The data on the comparison of the specificity and reproducibility of the new method with the currently used ones for determination of oxacillin are presented.

Hydrogen-Ion Concentration↗
PubMed1978

[Extraction and polarimetric method of determining phenacetyl-D(-)-alpha-aminophenylacetic acid].

Equilibrium distribution of phenacetyl-D-(--)-alpha-aminophenylacetic acid obtained on fermentative hydrolysis of D,L-aminophenylacetic acid in a two-phase system (chloroform-water) was studied within a wide range of the substance concentration in the organic phase. It was shown than in the organic phase the distributing substance formed associates. The empirical equation: y = A + Bx describing the dependence of the effective distribution of the non-dissociated form of phenylacetyl-D-(--)-alpha-aminophenylacetic acid on its concentration in the organic phase was suggested. Coefficients A and B of the equation were determined and an equation for evaluating equilibrium concentrations in the equeous phase was suggested. On the basis of the studies an extraction-polarometric method for quantitative determination of phenacetyl-D-(--)-alpha-aminophenylacetic acid concentration was developed. The method consists of extraction of the non-dissociated form of phenylacetyl-D-(--)-alpha-aminophenylacetic acid with chloroform, determination of the equilibrium concentration of the distributing substance in the organic phase by the polarimetric method and subsequent estimation of the equilibrium and initial concentrations of the electrolyte in the aqueous phase.

Chloroform↗
PubMed1978

[Spectrophotometric method of determining the oxacillin in oxacillin preparations].

The early described procedure for quantitative determination of oxacillin with the spectrophotometric method was used for the assay oxacillin tablets, capsules and injection preparations. It was shown that the excipients used in tablets and capsules did not interfere with oxacillin determination. The reproducibility of the method is +/- 1.5--2 per cent. The results of oxacillin determination with the new method and the currently used methods were compared.

Capsules↗
PubMed1978

[Quantitative determination of the phenolic ester of phenylmalonic acid by an IR spectroscopy method].

A quantitative method was developed for determination of phenyl ether of phenylmalonic acid (I) in the presence of phenol. The method is based on measurement of the optic density of the characteristic absorption bands of I at 1133 and 1770 cm-1 of IR-spectrum. Absorption of I at the above frequencies responded to Ber's law. Determination of I (solution in methylen chloride) was carried out on a standard curve in accordance with equation y : bx for the both frequencies. The value of constants b of the direct regressions for the frequencies of 1133 and 1770 cm-1 were determined with relative errtor of +/- 1.2 and 2.3 per cent respectively. The correlation coefficients were equal to 0.98 and 0.95.

Chromatography, Thin Layer↗
PubMed1977

[Chromatographic separation of rifamycins on a thin sorbent thin layer].

A method of simultaneous separation of rifampicins O, S and rifamicin derivates S, SV in a thin layer of silica gel KSK No. 2 impregnated with acetate buffer, pH 4.6 in a solvent system chlorophorm-methanol (100:5) was developed. The minimum detectable amount of the compounds studied was 1--2gamma, when the coloured zones were estimated visually.

Buffers↗
PubMed1977

[Spectrophotometric determination of rifampicin S in the presence of rifampicin O].

The limits of the use of the methods of direct photometric and differential spectrophotometric determination of rifamycin S containing rifamycin O as an admixture were discussed. The method of direct photometry did not provide determination of rifamycin S in the presence of rifamycin O since instability of the latter under the analysis conditions. A possibility of using the differential-spectrophotometric method for determination of rifamycin S in the presence of not more than 5 per cent of rifamycin O was shown.

Buffers↗
PubMed1977

[Quantitative determination of the gentamicin and dimethyl sulfoxide in the "Gentaplast" film-forming aerosol preparation].

A method for quantitative determination of gentamicin and dimethylsulfoxide (DMSO) in "Gentaplast", a film-forming aerozol preparation was developed. Gentamicin was determined microbiologically after extraction. DMSO was determined by titration with the use of the Redox method. The results of determination of gentamicin and DMSO in "Gentaplast" were statistically treated.

Aerosols↗
PubMed1976

[Quantitative determination of 7-phenoxyacetamidodesacetoxycephalosporanic acid].

7-Phenoxyacetamidodesacetoxycephalosporanic acid, an intermediate product in synthesis of cephalexin, was prepared by oxydation of phenoxymethylpenicillin into the respective sulphoxide and transformation of the latter. The UV-spectra of the reaction products were studied. A quantitative method is proposed for determination of 7-phenoxyacetamidodesacetoxycephalosporanic acid in the finished products based on estimation os the coefficient of specific extinction of the ethanol solutions at a wave length of 268 um in the UV-spectrum region in combination with semiquantitative estimation of the admixtures with the method of thin-layer chromatography.

Cephalexin↗
PubMed1976

[Quantitative determination of anhydroleandomycin and glycol in oleandomycin phosphate].

A spectrophotometric method for determination of inactive admixtures in oleandomycin phosphate-anhydrooleandomycin was developed. The method was based on measuring optical density of methanol solutions of oleandomycin and its admixtures at a wave length of 235 nm of UV-spectrum. The minimun detectable amount was 0.5 per cent. A method of thin-layer chromatography in a buffered fixed layer was developed for determination of the 2nd inactive admixture, i.e. glycole. The chromatogrammes were developed with xanthydrol. The minimum detectable amount was 3 mug.

Anhydrides↗
PubMed1976

[Chromatographic control of the process of rifamycin B isolation and purification].

A method of chromatography in a thin layer of Silica Cel No. 2 was developed for rifamicin B, rifamicin complex and some admixtures. Extracts of rifamicin B in an organic solvent, aqueous buffer reextracts and dry preparations of rifamicin B were analyzed with the above method. A half-quantitative chromatographic procedure for estimation of the main admixture in dry preparations was proposed.

Buffers↗
PubMed1976

[Increasing the threshold sensitivity of the spot detection reaction on a chromatogram].

A known analytical procedure was used for increasing the sensitivity threshold of the reaction of the zone opening on chromatogrammes. The procedure was the following: the carboxylic acid admixtures determined chromatographically were previously extracted from dry samples of the test-compounds into an optimal solvent. The expediency of the procedure was shown on examples of phenylacetic, phenoxyacetic and isoxasolcarboxylic acids present as admixtures in semisynthetic penicillins and raw materials used for their preparation. The threshold sensitivity was increased by 6 to 9 times. The chromatographic separation was performed in a fixed layer of Silica Gel KSK treated with a buffer. The mobile phase was used in the form of a solvent system: n-heptan-glacial acetic acid (95:5).

Carboxylic Acids↗
PubMed1975

[Determination of neomycin in the film-forming aerosol preparation "Neotizol'"].

A colorimetric method for guantitative determination of neomycin in the aerozol preparation "Neotizol" was developed. The determination was performed after neomycin isolation from the film-forming composition with the carboxylic ion exchange resins IRC-50 and KB-2 containing 2.5-3 per cent of divinylbenzol. The results of the colorimetric determination were compared with the data of the microbiological assay. The results of neomycin determination in the aerozol preparation "Neotizol" were treated statistically.

Aerosols↗
PubMed1975

[Quantitative method for determining variamycin].

A quantitative spectrophotmetric method for the assay of variamycin in commercial samples was developed. It was based on the measurement of the optical density of variamycin solutions in 0.01 N hydrochloric acid at a UV spectrum wave length of 412 nm. A method of thin-layer chromatography for a semi-quantitative estimation of tetraside, the main admixture of variamycin was devised. On storage for 18 months the content of variamycin in the preparations did not change as compared to that at the moment of the drug manufacturing and the amount of tetraside in 18 months did not exceed 2 per cent.

Antibiotics, Antineoplastic↗