[A spectrophotometric method of analysis of fusidic acid]. / Spektrofotometricheskii metod opredeleniia fuzidievoi kisloty.

A spectrophotometric method for assay of fusidic acid is described. The method is based on reaction with a reagent consisting of acetic anhydride and concentrated sulfuric acid. Mathematical processing of the results of the main substance determination in fusidic acid preparations showed that the error did not exceed 2 per cent. Procedures for spectrophotometric assay of fusidic acid in control of the processes of its biosynthesis, isolation and purification were developed. The procedures provided control of the technological process of fusidic acid production.

[Determination of iodine-containing admixtures in semisynthetic penicillins]. / Opredelenie iodsoderzhashchikh primesei v nekotorykh polusinteticheskikh penitsillinakh.

Dependence of the values defining the content of iodine sorbing admixtures in semisynthetic penicillins on pH, reaction time and drug aliquots was studied. On the basis of this study a general approach to development of procedures for determining iodine sorbing admixtures in semisynthetic penicillins was suggested. Procedures for determination of iodine sorbing admixtures in carbenicillin, carfecillin, ampicillin, oxacillin, azlocillin and ampiox were developed.

[Penicillinase from B. licheniformis. Determination of the ionization constants of the enzymatic hydrolysis products of beta-lactam antibiotics]. / Penitsillinaza iz 8. licheniformis. Opredelenie konstant ionizatsii produktiv fermentativnogo gidroliza betalaktamnykh antibiotikov.

The level of transformation of beta-lactam antibiotics hydrolysed by penicillinase from B. licheniformis on determination with the method of pH-metric titration with sodium hydrate solutions depended on the electrochemical nature of the products formed. The data on the study of the pH dependence of the penicillinase-catalysed hydrolysis of beta-lactam antibiotics were used for estimation of the ionization constants of the products of the enzymatic hydrolysis of the beta-lactam ring in the molecules of azlocillin, carfecillin, benzylpenicillin, cephalothin and 7-PADCA. Methods for quantitative determination of the compounds were developed. The methods are based on penicillinase-catalysed enzymatic hydrolysis and pH-metric titration of the products with sodium hydrate solutions at pH 7.0 with regard to their dissociation levels.

[Extractive polarographic method of controlling the stereospecific hydrolysis of N-acylated derivatives of amino acid racemates]. / Ekstraktsionno-poliarimetricheskii metod kontrolia stereospetsificheskogo gidroliza N-atsilirovannykh proizvodnykh ratsematov aminokislot.

The equilibrium distribution of acetyl-D-phenylglycine prepared with stereospecific hydrolysis of acetyl-D,L-phenylglycine (Ac-D,L-PhG) was studied in a two-phase system of benzyl alcohol-1N HCl solution. It was found that the distribution coefficient of Ac-D-PhG did not practically depend on its concentration in the aqueous phase. This means that Ac-D-PhG does not form associates in the organic phase. The studies provided development of an extraction polarimetric method for quantitative determination of Ac-D-PhG. The method implies extraction of Ac-D-PhG with benzyl alcohol from a strong acid medium (1N HCl solution), polarimetric determination of the equilibrium concentration of Ac-D-PhG in the organic phase and subsequent calculation of the initial concentration of Ac-D-PhG in the aqueous phase with regard to its distribution coefficient.

[E. coli penicillin amidase. Methods for estimating the close ionization constants of ionogenic groups of the enzyme complex with substrates containing free amino groups]. / Penitsillinamidaza iz E coli. Metody rascheta blizkikh konstant ionizatsii ionogennykh grupp kompleksa fermenta s substratami, soderzhashchimi svobodnye aminogruppy.

The possible use of various procedures for estimation of the ionization constants of the Michaelis complex by the pH dependence of the maximum enzymatic reaction rate is discussed. It is shown that the procedures described in the literature for estimation of the close ionization constants of the enzyme-substrate complexes have limitations and in some cases cannot be used. The paper presents the methods for estimation of the constants and means for quantitative description of the bell-shaped pH dependence of the kinetic and equilibrium parameters of the biocatalytic reaction. The equations recommended in the paper were used in analysis of the pH dependences of the maximum rate of the reactions during the enzymatic synthesis of cefalexin catalysed with immobilized penicillinamidase (IPA) (CE 3.5. 1.11). The ionization constants of the enzyme-substrate complexes of IPA were compared during hydrolysis and synthesis of the compounds acylated with phenylacetic and aminophenylacetic acids. The effect of the nature of the leaving substrate group and added nucleophilic gent on the electrochemical state of the Michaelis complex is discussed.

[Penicillin amidase from E. coli. The determination of the ionization constants of the Michaelis complex ionogenic groups in the enzymatic deacylation reactions of the phenacetyl derivatives of phenylglycine and 7-aminodesacetoxychephalosporanic acid]. / Penitsillinamidaza iz E. coli. Opredelenie konstant ionizatsii ionogennykh grupp kompleksa Mikhaélisa v reaktsiiakh fermentativnogo deatsilirovaniia fenatsetil'nykh proizvodnykh fenilglitsina i 7-aminodezatsetoksitsefalosporanovoi kisloty.

pH and temperature relationships of the maximum rate of the reaction of enzymatic hydrolysis of phenacetyl derivatives of phenylglycine (PPG) and 7-aminodesacetoxycephalosporanic acid (7-PADCA) catalysed by immobilized penicillinamidase (IPA) (penicillinamidohydrolase CE 3.5.1.11) were studied. A possibility of applying for the routine methods used in determination of electrochemical properties of ampholites for estimation of the ionization constants of the functional groups of both the enzyme and the enzyme-substrate complex was shown. The applicability of various methods for estimation of the ionization constants is discussed and the ways of determination of the ionization constants and the means of quantitative description of the bell-like pH relationship of the kinetic and equilibrium parameters of the biocatalytic reaction are presented. The equations described were used in analysis of the pH relationship of the immobilized penicillinamidase enzymatic activity in the reactions of 7-PADCA and L-PPG hydrolysis. The estimated ionization constants of the ionogenic groups of the Michaelis complexes were used in quantitative description of the electrochemical state of the complexes at wide pH ranges. The acid properties of the PA and IPA complexes with a number of substrates, such as benzylpenicillin, 7-PADCA, L-PPG and PANAB were compared. The effect of the immobilization procedure, electrochemical properties of the substrates and the reaction products on the electrochemical state of the Michaelis complexes is discussed.

[Penicillin amidase from E. coli. The kinetic and equilibrium parameters of the enzymatic hydrolysis of 7-phenylacetamidodesacetoxycephalosporanic acid catalyzed by an immobile enzyme]. / Penitsillinamidaza iz E. coli. Kineticheskie i ravnovesnye parametry fermentativnogo gidroliza 7-fenilatsetamidodezatsetoksitsefalosporanovoi kisloty, kataliziruemogo immobilizovannym fermentom.

The kinetics of 7-phenylacetamidodesacetoxycephalosporanic acid (7-PADCA) catalyzed by immobilized penicillinamidase was studied. The kinetic and equilibrium parameters of the reaction were determined by analysis of the kinetic curves of the reaction product accumulation. Inhibition of the enzymatic reaction by the substrate and hydrolysis products was studied. It was found that the Michaelis complex completely lost its activity after attachment of the substrate second molecule to it. The values of the Michaelis constants, catalytic constant and constants of inhibition by the substrate and reaction products were determined: Km = (9.3 +/- 1.1) . 10(-5) M, kcat = (65 +/- 5) c-1, Ks = (1.4 +/- 0.1) . 10(-2) M, K1 (FAA) = (2.5 +/- 0.3) . 10(-4) M, K1 (7-ADCA) = (1.4 +/- 0.1) . 10(-1) M. The diffusion effect in the kinetic reaction catalyzed by immobilized penicillinamidase is discussed. The values of the Thiele modulus and the actual value of Km were calculated.

[Determination of a dimethylaniline mixture in the intermediate products for the production of semisynthetic penicillins]. / Opredelenie primesi dimetilanilina v poluproduktakh dlia proizvodstva polusinteticheskikh penitsillinov.

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.

[Quantitative determination of the phenolic ester of phenylmalonic acid by an IR spectroscopy method]. / Kolichestvennoe opredelenie fenilovogo éfira fenilmalonovoi kisloty metodom IK-spektroskopii.

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.

[Extraction and polarimetric method of determining phenacetyl-D(-)-alpha-aminophenylacetic acid]. / Ekstraktsionno-poliarimetricheskii metod opredeleniia fenatsetil-D(-)-al'fa-aminofeniluksusnoi kisloty.

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.

[Spectrophotometric method of determining the oxacillin in oxacillin preparations]. / Spektrofotometricheskii metod opredeleniia oksatsillina v preparatakh oksatsillina.

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.

[Use of the penicillanic acid formation reaction for the analysis of penicillins. The quantitative determination of oxacillin]. / Primenenie reaktsii obrazovaniia penitsillenovykh kislot dlia analiza penitsillinov. Kolichestvennoe opredelenie oksatsillina.

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.

[Quantitative determination of the gentamicin and dimethyl sulfoxide in the "Gentaplast" film-forming aerosol preparation]. / Kolichestvennoe opredelenie gentamitsina i dimetilsul'foksida v plenkoobrazuiushchem aérozol'nom preparate "Gentaplast".

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.

[Spectrophotometric determination of rifampicin S in the presence of rifampicin O]. / K voprosu o spektrofotometricheskom opredelenii rifampitsina S v prisutstvii rifampitsina 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.

[Chromatographic separation of rifamycins on a thin sorbent thin layer]. / Khromatograficheskoe razdelenie rifamitsinov v tonkom sloe sorbenta

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.

[Quantitative determination of 7-phenoxyacetamidodesacetoxycephalosporanic acid]. / Kolichestvennoe opredelenie 7-fenoksiatsetamidodezatsetoksitsefalosporanovoi kisloty

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.

[Increasing the threshold sensitivity of the spot detection reaction on a chromatogram]. / Povyshenie porogovoi chuvstvitel'nosti reaktsii otkrytiia zon na khromatogramme

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).

[Quantitative determination of anhydroleandomycin and glycol in oleandomycin phosphate]. / Kolichestvennoe opredelenie angidrooleandomitsina i glikolia v fosfate oleandomitsina

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.