FIELD: medicineSUBSTANCE: at the stage of sample preparation addition of internal standard to biological sample is performed simultaneously with deproteinisation by precipitation with 02% solution of formic acid in methanol, containing internal standard norvalin Sample and reagent are taken in volume ratio 1:1-1:2, then separation and detection of homoarginine is performed by high performance liquid chromatography with pre-column derivatisatuion with ortho-phthalcic aldehyde and fluorometric detection and determination of homoarginine concentration by obtained chromatogramEFFECT: method makes it possible to avoid expensive consumables, required for carrying out solid-phase extraction, and is characterised by lower labour-consumption of sample preparation with comparable analytical characteristics2 dwg, 3 tbl, 1 ex

Method of determining homoarginine content in blood plasma and other human biological fluids

FIELD: chemistrySUBSTANCE: invention describes a method of determining concentration or content of ascorbic acid in liquid drug formations, involving preparation of doses of an analysed sample and a standard sample, wherein 06 ml of a sodium phosphate buffer (005 mol/l, pH 8,3), 01 ml of tetramethylene diamine solution (005 mol/l) in a sodium salt of ethylenediamine tetraacetic acid (02 mmol/l), 01 ml of the analysed sample and 02 ml of riboflavin solution (0034 mmol/l) are successively fed into a chemiluminometer cell; the same volume of distilled water is added to the control sample; further, the reaction is initiated by irradiation with a visible light lamp (100 W) at a distance of 20 cm for 60 s; 10 s before irradiation time expires, 01 ml of luminol solution (025 mmol/l) is added; after irradiation, the cell holder is moved into the operating position in front of the photocathode of a photomultiplier (about 1 s) in a biochemiluminometer and the chemiluminometer flash is detected; concentration of ascorbic acid in the mixture or content thereof is calculated in the same units it was recorded using a formulaEFFECT: method is characterised by optimum rapidness, easy preparation of samples for analysis and high reproducibility and accuracy4 ex, 1 tbl, 1 dwg

Method of determining concentration of ascorbic acid

FIELD: chemistry.SUBSTANCE: method comprises preparing a water-brine mixture tyrosine and vitaminBby dissolving them in a saturated solution of salting-out agent, which is used as an ammonium sulfate concentration of 15-20 wt %, and extraction of aqueous phase equilibrium analysis. The method is characterized in that the extractant used is a block copolymer solution "Pluronic F-123" with a concentration of 0.09 g/cm. For this purpose, an aqueous saline solution with a concentration of tyrosine 2.4-3.0 mg/cmand vitamin Bat a concentrationof 1.8⋅10-2.5⋅10mg/cm. Then extracted by adding a solution of the block copolymer to the aqueous-salt solution of tyrosine and vitaminBwhen the volume ratio of the water-salt mixture tyrosine and vitaminBand the block copolymer is 5:1 at a temperature of 20±1°C for 7-10 min. After phase separation the aqueous phase is separated from the organic, determined electrophoretically tyrosine content in the aqueous phase at a wavelength of 254 nm, a leading electrolyte - phosphate buffered saline supplemented with β-cyclodextrin (pH 7.8±0.2), and vitaminBmeasured at a wavelength of 200 nm, a leading electrolyte - borate buffer solution (pH 8.9±0.2). For this purpose, two recorded electrophoretogram prepared sample of each portion, obtained on the correctness electrophoregrams check mark automatic peak using the software "Elforan" hold identification of components in a sample, distribution ratios Dextent and R(%) amino acid extract and vitamin calculated by the formulas shown below, whereCо and Cв - amino acid or vitamin concentration in the organic and aqueous phases, respectively, mol/dm, R - the ratio of the equilibrium amounts of the aqueous and organic phases.EFFECT: method allows almost completely removing tyrosine and vitaminBfrom an aqueous salt mixture in a single extraction.1 ex

Method for extracting tyrosin and vitamin bfrom water solution

FIELD: chemistry.SUBSTANCE: method of extracting theobromine from aqueous solutions involves preparation of an aqueous salt solution of theobromine via dissolution thereof in a saturated solution of a salting-out agent, extraction and analysis of the equilibrium aqueous phase, where theobromine is extracted with a solution of a solvotropic reagent, specifically dioctyl phthalate in an ethyl acetate/chloroform mixture (0.2:0.8 mole fractions, respectively) with concentration of 0.85-0.90 mol/dmfor 7-10 minutes from the aqueous salt solution of theobromine, having pH 4.3±0.5. The ratio of the volume of the aqueous salt solution of theobromine to that of the extractant is equal to 10:1; the salting-out agent used is ammonium sulphate solution. Further, the water-salt phase is separated from the organic phase and analysis is carried out via UV spectrophotometry at wavelength of 272 nm; concentration of theobromine in the analysed aqueous solution is determined from a calibration curve, and the distribution coefficient (D) and degree of extraction of theobromine (R, %) are calculated using formulae.EFFECT: method of extracting theobromine from aqueous solutions is characterised by rapidness and enables to achieve virtually full extraction of theobromine from an aqueous salt solution.1 ex

Method of extracting theobromine from aqueous solutions

FIELD: chemistry.SUBSTANCE: saccharose and phenylalanine solutions are prepared in a small volume of water, put into a measuring flask and brought up to the volume with a saturated solution of a salting-out agent in form of ammonium sulphate; saccharose and phenylalanine are then extracted by adding acetone to the obtained aqueous salt solution of saccharose and phenylalanine with the volume ratio of the aqueous salt solution of saccharose and phenylalanine to acetone of 20:1; extraction is carried out for 7-10 minutes; after demixing of the system, the aqueous phase is separated from the organic phase; content of saccharose in the aqueous phase is determined from a reaction with potassium dichromate in the presence of sulphuric acid; a photoelectric colorimeter is used to measure optical density of the coloured solution at wavelength 590 nm (thickness of the light-absorbing layer of 1 cm); a calibration curve of optical density of the solution versus concentration of saccharose is plotted; the calibration curve is used to determine concentration of saccharose in the aqueous phase; the organic phase is quantitatively transferred into a cell for potentiometric titration and titrated with 0.01 mol/l KOH solution in anhydrous ethyl alcohol; the indicator electrode is a glass electrode; the comparison electrode used is a silver chloride electrode filled with saturated KCl solution in ethyl alcohol; the electromotive force of the solution is measured on a high-resistance potentiometer; there is a maximum on the differential curve of potentiometric titration which corresponds to content of phenylalanine in the extract.EFFECT: easier, more reliable and safer analysis.1 ex

Method for separate determination of saccharose and phenylalanine

FIELD: analytical chemistry of organic compounds, amino acids. ^ SUBSTANCE: invention relates to a method for selective determination of tyrosine and phenylalanine in an aqueous solution that involves preparing an aqueous-saline solution of tyrosine and phenylalanine mixture, extraction of these amino acids with an extractant representing a mixture of hydrophilic solvents. Analysis of an organic phase involves addition of lithium sulfate as a desalting agent to an aqueous solution of amino acids analyzed in the amount 20-25 wt.-% to the solution mass. As an extractant the method involves using three-component mixture of hydrophilic solvent consisting of 45-45.5 wt.-% of isopropyl alcohol, 30-30.5 wt.-% of acetone and 24-25 wt.-% of ethyl acetate in the volume ratio of solvents mixture and aqueous-saline solution = 1:10. The potentiometric titration method is used for analysis of an organic phase. Proposed method provides the selective determination of tyrosine and phenylalanine in an aqueous solution by using liquid extraction and in enhancing precision of analysis. Invention can be used in development of processes for continuous fermentation of proteins. ^ EFFECT: improved assay method. ^ 1 tbl, 9 ex

Method for selective determination of tyrosine and phenylalanine in aqueous solution

FIELD: chemistry. ^ SUBSTANCE: invention relates to analytic chemistry of organic compounds concerning elaboration of processes of vitamin isolation and separation. Method includes preparation of water-salt solution of ascorbic acid by its dissolving in saturated desalter solution, extraction of ascorbic acid, analysis of equilibrium water phase, as desalter for preparation of water-salt solution of ascorbic acid, saturated solution of ammonium sulphate or sodium sulphite is used; water-salt solution of ascorbic acid is prepared with pH 5, for which purpose weighed portion of ascorbic acid with weight 1 mg, measured on analytic scales, is carried to measuring flask, which has volume 100 ml, and bring to the mark with saturated solution of ammonium sulphate or sodium sulphite, extraction of ascorbic acid is carried out by water solution of polymer poly-N-vinylpyrrolidone with concentration 10-5 mole/l with ratio of polymer solution and water-salt solution volumes 1:5. ^ EFFECT: increased degree of ascorbic acid extraction from water solution and increase of analysis safety. ^ 2 cl, 1 tbl

Method of detecting ascorbic acid in water solution

FIELD: chemistry. ^ SUBSTANCE: aqueous extract of amino acids is prepared from a preparation which contains arginine, isoleucine and lysine as active components. A salting-out agent in form of lithium sulphate is added in amount of 20-25 wt %. The solution is stirred and then mixed in volume ratio 1:10 with a mixture of hydrophylic solvents consisting of 30 wt % n-butyl alcohol, 30 wt % ethylacetate and 40 wt % acetone. The mixture is stirred and extraction is carried out for 20 minutes. The extract is separated and content of arginine, isoleucine and lysine is determined through capillary electrophoresis using the Kapel-105 system. Detection is possible at concentration level of 5-15 mg/ml. ^ EFFECT: increased accuracy of detecting the said compounds. ^ 2 ex, 1 tbl

Method of detecting arginine, isoleucine and lysine in polyamino acid preparations

FIELD: chemistry. ^ SUBSTANCE: method of detecting nicotinic acid in aqueous solution involves preparation of an aqueous salt solution of nicotinic acid by dissolving it in a saturated solution of a salting-out agent, its extraction and analysis of the equilibrium aqueous phase. The method is distinguished by that, the salting-out agent used in preparing the aqueous salt solution of nicotinic acid is a saturated solution of ammonium sulphate. The aqueous salt solution of nicotinic acid is prepared with pH 6.5, for which a weighed amount of nicotinic acid of mass 2 mg, weighed on an analytical balance, is put into a 100 ml graduated flask which is then filled with a saturated solution of ammonium sulphate, or sodium sulphite, or ammonium sulphite. Nicotinic acid is extracted with an aqueous polymer solution of poly-N-vinyl-pyrrolidone with concentration of 10 to 5 mol/l with volume ratio of the polymer solution to aqueous salt solution equal to 1:5. ^ EFFECT: increased extraction ratio of nicotinic acid from the aqueous solution. ^ 1 cl, 1 ex, 1 tbl

Method of detecting nicotininc acid in aqueous solution

FIELD: analytical chemistry of organic compounds, possibly standard analysis at production of pharmaceutical preparations such as biologically active food supplements, amino acid mixtures, vitamin complexes. ^ SUBSTANCE: method comprises steps of preparing aqueous solution of tryptophan and phenylalanine at initial concentration 0.05 and 0.02 mg/ml respectively; adding to prepared solution salting out agent -crystalline lithium sulfate till its content 25 mass% in relation to mass of aqueous solution of amino acids; adding to prepared aqueous -salt solution of tryptophan and phenylalanine extragent - three-component mixture of hydrophilic solvents at volume relation of aqueous-salt solution and extragent mixture 10 : 1; preparing mixture of hydrophilic solvents from 60-70 mass% of butyl alcohol, 20 -25 mass% of acetone and 5 -20 mass % of ethyl acetate; then extracting it in vibration mixer for 5 min; curing for several minutes until complete separation of phases; transferring extract to cell for conductometric titration and determining in extract content of tryptophan and phenylalanine. In order to realize it curve is plotted according to result of titration determining relationship of electrical conductivity of solution upon volume of added titrant; detecting with use of fixed points of equivalence mass of tryptophan and phenylalanine in extract. Extraction degree of tryptophan and phenylalanine is calculated with use of formula: R = D - 100/D + r, where D -coefficient of distribution of tryptophan and phenylalanine between three-component mixture of hydrophilic solvents and aqueous-salt solution; r - relation of volumes of aqueous and organic phases. Method allows determine up to 97 =98% of tryptophan and 98 -99% of phenylalanine. ^ EFFECT: enhanced efficiency of selective determination of tryptophan and phenylalanine in aqueous solution. ^ 2 notes, 1 tbl

Pakhomova Oksana Anatol Evna

Papers

Method for selective determination of tyrosine and phenylalanine in aqueous solution

Method of detecting ascorbic acid in water solution

Method of detecting arginine, isoleucine and lysine in polyamino acid preparations

Method of detecting nicotininc acid in aqueous solution

Method for selective determination of tryptophan and phenylalanine in aqueous solutions