Method for ion-exchange separation of methionine and glycine

FIELD: chemistry.

SUBSTANCE: invention relates to a method for ion-exchange separation of methionine and glycine and can be used in biochemistry, pharmaceutical and food industry. The method involves separation of methionine and glycine in two steps. At the first step amino acids undergo sorption with enrichment of the sorbent phase with glycine, and the solution at the output enriched with methionine. For this purpose, polyampholyte Purolite S950 in H-form is prepared. The mixture of two aliphatic amino acids undergoes sorption in a countercurrent column with a fixed sorbent layer. For this purpose, a solution containing a mixture of glycine and methionine is fed from below and glycine is undergoes sorption on polyampholyte Purolite S950. Methionine, appears at the output, the aqueous solution of which is sorbed in a receiver at the output of the column and after a certain time - the amino acids. Sorption is stopped. During sorption, samples are collected at defined time intervals. Total concentration of amino acids is controlled using an iodimetric method, and concentration of methionine is controlled using a spectrophotometric method, while glycine concentration is controlled based on concentration difference: between total concentration and methionine concentration. The degree of separation of the initial solution is equal to 60%. At the second step, glycine is eluted with hydrochloric acid solution at pH 1.2 from the sorbent while feeding glycine-containing eluate from the top, and sorbed in the receiver. Concentration of glycine is equal to 70%. After desorption of glycine, the mixture of amino acids undergoes complete desorption. Polyampholyte takes the initial shape and is ready for operation. Samples are collected at defined time intervals and each sample is analysed using iodometric and spectrophotometric methods. For complete separation of glycine from methionine, the two-step process of separating the mixture of amino acids obtained at the output of the column is repeated.

EFFECT: method enables efficient separation of methionine and glycine by combining sorption and desorption processes while excluding the sorbent regeneration step, and reduce the volume of wash water without using considerable amount of auxiliary reactants.

2 dwg, 2 tbl, 1 ex

 

The invention relates to methods of division and separation of individual aliphatic amino acids from mixtures thereof and can be used in biochemical, pharmaceutical and food industries.

The closest in technical essence and the achieved effect is the way the classical ion-exchange chromatography [A.S. USSR N 979991, G01N 31/08, 1981], which is based on sorption of molecules of a substance stationary phase, due to their electrostatic binding with the surface of the porous granules of the solid hydrophilic sorbent in contact with the solution.

The disadvantages are the use for regeneration of the sorbent large number of auxiliary reagents, availability of preliminary preparation of amino acid solutions before passing them through the ion exchanger and the flow in the system of the ion exchanger - sorbent various non-interactions, which complicates the process of separating amino acids and leads to large amounts of wash water and low separation efficiency.

The technical problem of the invention is to develop a method of ion-exchange separation of methionine and glycine, which can increase the efficiency of the separation of a mixture of amino acids, to exclude from the process a large number of auxiliary reagents, to reduce the amount and extent the ü sewage contamination.

To solve the technical problem of the invention, a method of ion-exchange separation of methionine and glycine, characterized in that the separation of aliphatic amino acids methionine and glycine is carried out in two stages, the first stage is conducted sorption of amino acids enriched phase sorbent glycine, and the solution on output - methionine, to do this, prepare polyampholyte Purolite S950 in the H+form, spend the sorption of a mixture of two aliphatic amino acids in countercurrent column with a fixed bed of sorbent, for this bottom-miss solution containing a mixture of glycine and methionine, while glycine adsorbed on polyampholyte Purolite S950, the output appears methionine, an aqueous solution which is collected in the receiver at the outlet of the column, after some time - a mixture of amino acids, sorption stop during sorption make sampling after a certain period of time, control the total concentration of amino acids by iodometric method, methionine - spectrophotometric method, glycine is the difference of concentrations: total and methionine, the degree of source separation the solution is 60%, in the second stage is conducted elution glycine-hydrochloric acid pH of 1.2 from the sorbent feed above, the eluate containing glycine, collected in the receiver, the degree of concentration of glycine extending t is 70%, after desorption of glycine conduct a complete desorption of a mixture of amino acids, polyampholyte takes the original shape and ready to go, also take samples after a certain period of time and analyze each sample iodometric and spectrophotometric methods for complete removal of glycine from methionine repeat two-stage process for the separation of mixtures of amino acids, obtained at the outlet of the column.

The technical result consists in increasing the efficiency of separation of mixtures of amino acids, the exclusion from the process of auxiliary reagents, the increase in the yield of amino acids and the decrease in the volume of wash water.

Figure 1 shows the dependence relationship of the concentration of amino acids in solution at the outlet of the column to the initial concentration (c/c0from the time of sorption (t, min) methionine (curve 1) and glycine (curve 2) on Purolite S950 (H+) at 298 K and the speed of transmission 7 cm3/min

Figure 2 presents the dependence of the relationship of the concentration of amino acids in the eluate concentration in the resin (c/c0from time desorption (t, min) glycine (curve 1) and methionine (curve 2) from Purolite S950 solution of hydrochloric acid with a pH of 1.2 and a bandwidth of 8 cm3/min

The method of ion-exchange separation of aliphatic amino acids glycine and methionine from aqueous solutions implement is as follows.

Separation of amino acids is carried out in two stages: the first stage - sorption of a mixture of amino acids enriched liquid phase methionine and solid phase glycine, the second stage - elution with an enriched solution of glycine.

In the column load polyampholyte Purolite S950; the preparation of the resin is as follows: pass through the layer of ion exchanger sequentially a solution of KOH with a concentration of 0.5 mol/DM3, distilled water, hydrochloric acid solution with a concentration of 0.5 mol/DM3water to remove hydrochloric acid from migrenoznogo space, polyampholyte transferred to the N+-shape and ready for use; conduct sorption, for this bottom-miss solution containing a mixture of glycine and methionine, the output from the column first appears methionine, after some time - a mixture of amino acids, separation of the initial solution is 60%, the sorption stop. During the sorption after a certain period of time take samples of the solution at the outlet of the column. The total concentration of amino acids in solution determined by iodometric method. The concentration of methionine in the samples determined by a spectrophotometric method. The concentration of glycine is calculated based on the difference between the total concentration of amino acids and methionine.

In the second stage is carried out by the des is rblu glycine from polyampholyte solution of hydrochloric acid with a pH of 1.2 with the flow of eluent from the top. The degree of concentration of glycine is 70%. During desorption analyze selected after a certain period of time solutions iodometric and spectrophotometric methods. After elution of glycine and mixtures of amino acids polyampholyte takes the original shape and ready to work.

For a better separation of amino acids ion-exchange cycle, consisting of two steps, repeat.

The use of sorbent polyampholytes nature allows to achieve a high degree of separation of aliphatic amino acids (glycine and methionine)that have similar physico-chemical characteristics and differ in the length of the hydrocarbon radical. The volume of the partial solutions and initial concentration of amino acids can be different, therefore, the required capacity of ion exchangers varies, in this regard, characteristics of ion-exchange columns (height, diameter, flow rate of solution, the volume of the sorbent and so on) are selected for each case separately.

The method of ion-exchange separation of methionine and glycine is illustrated by the following example.

Example. Separation of amino acids carried out from an aqueous solution containing glycine 0,025 mol/DM3and methionine 0,0026 mol/DM3prepared by dissolving amino acids brand "Reanal" in distilled water. Sorption and desorption of glycine Khujand who are on the ampholyte Purolite S950 in the H +form in the colon with an inner diameter of 56 mm and a height of 158 mm column load polyampholyte Purolite S950 is passed through the layer of ion exchanger solution of KOH with a concentration of 0.5 mol/DM3then distilled water, followed by a solution of hydrochloric acid with a concentration of 0.5 mol/DM3and again with water to remove hydrochloric acid from migrenoznogo space. At the first stage of separation are sorption, feeding to the column a solution of amino acids upwards with a speed of 7 cm3/min. sampling at the outlet of the column carried out after 10 minutes with a precisely fixed time for further development of the output curves. Data on the sorption of a mixture of glycine-methionine in aqueous solution are presented in table 1.

Determination of total concentration of amino acids in the eluate carried out by iodometric titration. To do this in a volumetric flask of 50 cm3the pipette to add 5 cm3the investigated alkaline solution containing amino acid. From the cylinder poured 30 cm3freshly prepared phosphate of copper, the contents of the flask was adjusted to the mark with water, mixed and filtered through a filter with a blue ribbon. The filtrate should be transparent. Then 10 cm3the filtrate pipette contribute in a conical flask, add 0.5 cm3glacial acetic acid and 7 cm310% solution of potassium iodide. After moving the air traffic management the liberated iodine is titrated from microburette the sodium thiosulfate solution with a concentration of 0.01 mol/DM 3by adding at the end of the titration 1-2 drops of freshly prepared starch solution, the equivalence point is determined by the disappearance of the blue color.

The presence of methionine in the samples determined by a spectrophotometric method. To do this in a volumetric flask and make the volume of solution of methionine, such that its concentration was in the range of the calibration curve from 0.0005 to 0.001 mol/DM3then add a solution of nitric acid to pH 1 and bring the volume of the solution up to the mark with distilled water. Before starting measurements on a portable spectrophotometer UVMini-1240 carry out calibration with distilled water. Then poured into a cuvette solutions containing methionine (met), and measure the optical density (A) in the range of wavelengths from 190 to 250 nm. To check compliance with the maximum building differential absorption spectrum, determine the optical density of the solution at λ=211 nm. On the calibration function constructed in the coordinates A=f(cmet)set the concentration of methionine and recalculate the concentration in the original solution.

The concentration of glycine in aqueous solution is determined by the difference between the total concentration of amino acids and methionine. The results are shown in figure 1 and figure 2.

As can be seen in figure 1, the allocation of methionine from a solution with glycine occurs in the interval is the time from 110 to 175 min from the beginning of the sorption. The optimal time of separation of glycine and methionine when sorption is 150 min from the beginning of the process, the degree of separation is 60%.

The desorption process of glycine from the solution with methionine is solution of hydrochloric acid with a concentration of 0.1 mol/DM3that is fed into the column from top to bottom, with a bandwidth of 8 cm3/min

Control is carried out by sampling at the outlet of the column after every 10 min and further analysis. Determination of the concentration of amino acids carry out the above method. Data on the desorption of a mixture of glycine-methionine is presented in table 2.

As can be seen from figure 2, the output curves of desorption of glycine and methionine are almost parallel. The concentration of glycine is 70% in the time interval of elution from 40-110 minutes

If necessary, through the column again pass the mixture of amino acids obtained earlier at the outlet of the column (containing glycine and the remaining methionine). As a result, get a solution of methionine, glycine adsorbed on the resin. After this, the process of glycine elution with hydrochloric acid and washing the sorbent with water again.

As can be seen from the examples, tables and figures, the allocation of methionine occurs at the stage of sorption of a mixture of amino acids, and the selection of glycine - elution, while the ion exchanger power is it in original working condition.

The proposed method is ion-exchange separation of methionine and glycine allows effective sharing of the aliphatic amino acids glycine and methionine from hydrolysates of different Genesis and biochemical wastewater by a combination of processes of sorption and desorption, to avoid a stage of regeneration of the sorbent, the use of a substantial amount of auxiliary reagents and the stage of preliminary preparation of amino acid solutions before passing through the ion exchanger, to reduce the amount of wash water.

Table 1
The method of ion-exchange separation of methionine and glycine
No. sample1234567891011
Time selection, min95112132162215250265 270275285300
Total concentration, mol/DM300,000010,00070,00170,01180,0220,02360,02480,02560,02640,027
The concentration of methionine, mol/DM300,000010,00070,00170,001720,002190,002230,002180,002240,002050,00196
The concentration of glycine, mol/DM300000,010,020,0210,02260,0230,0240,025
CCH/c0 CH00000,3950,7770,8380,8870,9160,9550,982
Cmeth/c0 m00,0040,280,680,840,880,890,870,890,820,79

Table 2
The method of ion-exchange separation of methionine and glycine
The sample number123456789
Time selection, min40 7893108123142147160200
Total concentration, mol/DM30,030,020,01240,00760----
The concentration of glycine, mol/DM30,0250,0170,010,00530,00120---
The concentration of methionine, mol/DM30,00260,00260,00260,00250,00140,00080,00070,000020
Camounts/c0 totals1 0,670,410,250----
CCH/c0 CH10,680,40,2120,0480---
Cmeth/c0 m1110,950,550,320,26ml0

The method of ion-exchange separation of methionine and glycine, characterized in that the separation of aliphatic amino acids methionine and glycine is carried out in two stages, the first stage is conducted sorption of amino acids enriched phase sorbent glycine, and the solution on output - methionine, to do this, prepare polyampholyte Purolite S950 in the N+form, spend the sorption of a mixture of two aliphatic amino acids in countercurrent column with a fixed bed of the sorbent, this bottom will roboscout solution containing a mixture of glycine and methionine, while glycine adsorbed on polyampholyte Purolite S950, the output appears methionine, an aqueous solution which is collected in the receiver at the outlet of the column, after some time - a mixture of amino acids, sorption stop during sorption make sampling after a certain period of time, control the total concentration of amino acids in the iodometric method, methionine - spectrophotometric method, glycine is the difference of concentrations: total and methionine, the degree of separation of the initial solution is 60%, in the second stage is conducted glycine elution solution of hydrochloric acid with a pH of 1.2 from the sorbent feed from the top, the eluate containing glycine, collected in the receiver, the degree of concentration of glycine is 70%, after desorption of glycine conduct a complete desorption of a mixture of amino acids, polyampholyte takes the original shape and ready to go, also take samples after a certain period of time and analyze each sample iodometric and spectrophotometric methods for complete removal of glycine from methionine repeat two-stage process for the separation of mixtures of amino acids, obtained at the outlet of the column.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: air containing volatile and semi-volatile organic compounds with the said elements is passed through a cartridge with a composite sorbent which facilitates concentration of trace amounts of volatile and semi-volatile organic compounds from air and their thermal desorption in an oxygen current, with subsequent absorption of the conversion products with deionised water, obtaining a concentrate and its ion chromatographic analysis in isocratic conditions.

EFFECT: method enables to achieve complete conversion for different analyses of F-, Cl-, Br-, I-, S- and P-organic compounds in proposed conditions.

4 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention describes a novel method for simultaneous determination of content of fluorine, chlorine, bromine, iodine, sulphur and phosphorus in organic compounds by putting a sample of the analysed substance into a stream of oxygen in a reactor at high temperature. The high temperature oxidation products are absorbed with water or eluent which is used for separating anions. Carbon dioxide obtained during the process is blown off from the absorber using a stream of oxygen or an extra stream of inert gas. A small portion of the absorbate is taken to the separation column through a protective column and anions which correspond to the determined elements in the compound in the standard substance via ion chromatography. If necessary, a sample of deionised water which is free from the elements under analysis is fed into the reactor after absorption of the conversion products. Oxidation products are washed from the walls of the reactor into the absorber and the obtained absorbate is analysed. In order to simplify the process, the preferred absorber is a single-use syringe. In case of simultaneous micro-determination of fluorine, chlorine, bromine, iodine, sulphur in organic compounds, a sub-sample is prepared first in form of a solution of given concentration of the analysed substance and the standard substance which does not contain the elements to be determined but contains an element which is not among elements of the analysed substance, in a solvent which does not contain the detected elements.

EFFECT: provision for complete conversion of anions which correspond to the determined elements.

4 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention discloses a method for simultaneous determination of total content of F-, Cl-, Br-, I-, S- and P-organic compounds in oil and oil refining products. The method involves putting a sample into a reactor and high-temperature oxidative conversion using oxygen, absorption of the conversion products with deionised water which is free from the elements under analysis and analysis of the obtained solution through ion chromatography.

EFFECT: improved method.

5 cl, 5 tbl, 4 ex

FIELD: chemistry.

SUBSTANCE: disclosed method of determining total content of F-, Cl-, Br-, I-, S- and P-organic compounds in water or aqueous solutions involves extraction of the compounds from water, high-temperature conversion of the concentrate in an oxygen atmosphere, absorption of the conversion products with water and analysis of the obtained solution with an absorbate through ion chromatography. According to the proposed method, the degree of conversion for all analysed compounds (content of 10-8-10-6 g/mcl) is 100%.

EFFECT: higher accuracy.

5 cl, 2 tbl, 2 ex

FIELD: blasting.

SUBSTANCE: invention is based on principle of ionic mobility detection for detection of explosive substances vapors of explosive substances in the field of instrument inspection. Detection is carried out by means of air sampling from surface or from internal volume of investigated objects of samples analysis for content of specific components of explosive substances vapors. Principle of instrument operation is based on registration of ionograms (spectra of ionic mobility) of trace contaminants of substances in air. Instrument makes it possible to detect "clean", "industrial" and "primitive" ES (explosive substances) by means of registration of vapors of nitroorganic compounds.

EFFECT: invention provides for fast and operative detection and identification of explosive substances.

3 cl, 2 dwg

The invention relates to analytical chemistry

The invention relates to the field of analytical chemistry and can be used in metallurgy, chemical industry, environment, medicine, food industry

The invention relates to the field of rare earth elements and, more specifically, to the separation of isotopes of elements riskseeking

The invention relates to analytical chemistry and can be used in inframetrics separation and analysis of mixtures of anions in aqueous solutions, for example, in the wastewater chemical industries

FIELD: chemistry.

SUBSTANCE: analysed sample is infused with an organic insulating agent. The obtained extract is purified through chromatography on a column of silica gel L 40/100 µ, while performing elution with a mixture of organic solvents. The analysed substance is determined using a chromatographic technique using a mobile phase which contains hexane, dioxane and propanol-2. The organic insulating agent is toluene. The toluene extract is dehydrated with anhydrous sodium sulphate. During the purification process, hexane is first passed through the column and elution is then carried out with a hexane-dioxane-propanol-2 solvent mixture (8:3:0.6 by volume). Eluate fractions containing the analysed substance are merged. The eluent is evaporated. The residue is dissolved in the hexane-dioxane-propanol-2 solvent mixture (15:5:1 by volume) and detection is carried out using high-performance liquid chromatography (HPLC) in a 64×2 mm column filled with Silasorb-600 sorbent using a hexane-dioxane-propanol-2 mobile phase (15:5:1 by volume) and a UV detector.

EFFECT: high accuracy and sensitivity of analysis.

3 ex, 4 tbl

FIELD: medicine.

SUBSTANCE: there is described a method of quantitative cyclosporine A evaluation in patients' blood involving blood protein precipitation by adding an aqueous solution of zinc sulphate and methanol, mixing, centrifuging and sampling a centrifugate; separating the centrifugate ingredients by reverse phase high-yield liquid chromatography, mass-spectrometre detecting cyclosporine A and evaluating the cyclosporine A concentration with plotting a calibration curve; blood protein are precipitated with using whole blood; blood protein precipitation is followed by additional salt impurity precipitation by adding methanol to the centrifugate to the general concentration not less than 90 vol. %, mixing again, centrifuging and sampling the centrifugate; separating the centrifugate ingredients, detecting and evaluating the cyclosporine A concentration.

EFFECT: method allows facilitating analysis simplicity and universality with providing adequate sensitivity and selectivity ensured by the absence of necessity for the internal standard and online extraction and lower requirements to specification of the used mass spectrometre by conducting preliminary impurity precipitation.

1 ex

FIELD: physics.

SUBSTANCE: proposed method comprises forcing analysed product into chromatograph first circuit to define carbon sulphide at its concentration exceeding 0.1 wt % and, at a time, into second circuit at carbon sulphide concentration lower than 0.1 wt %. First circuit comprises piston-type metering valve and packed columns arranged in heated temperature-controlled cabinet and filled with polymer adsorbent, 0.1-1.5 m-long precolumn and 0.5-5 m-long main column, and heat conductivity detector. Second circuit comprises piston-type metering valve, packed capillary columns arranged in heated temperature-controlled cabinet and filled with polymer adsorbent, 0.1-1.5 m-long precolumn and 15-50 m-long main column with their ID making 0.23-0.32 mm, and sulfur-selective detector. Metering valves are arranged sequentially in both circuits along sample feed direction.

EFFECT: shorter easier process.

5 cl, 1 dwg, 2 tbl, 1 ex

FIELD: medicine.

SUBSTANCE: urine is sampled, centrifuged that is followed by solid-phase extraction with Oasis HLB sorbent with using 100% acetonitrile as an extraction fluid for dimethyl terephthalate extraction. Said solid-phase extraction is conducted by consequent passing 100% acetonitrile, distilled water, the urine sample after centrifugation, distilled water, 20% aqueous acetonitrile and 100% acetonitrile as the extraction fluid through the sorbent; then the prepared extract is analysed by liquid chromatography with using as a mobile phase mixed acetonitrile and water in the at the varying ratio 25:75 vol. % to 90:10 vol. % respectively in a gradient mode which is enabled with combining chromatography by supplying at first the mobile phase containing mixed acetonitrile and water in the ratio 25:75 vol. % for 10 minutes. Then increasing the acetonitrile concentration in the mobile phase to 90 vol. % for 5 minutes and passing such mobile phase for another 5 minutes is followed by decreasing a volume amount of acetonitrile to 25 vol. % for 5 minutes and passing such mobile phase through a column for 10 minutes, while an amount of dimethyl terephthalate is determined by a calibration chart.

EFFECT: high sensitivity of the method combined with selectivity and availability for routine analyses.

5 cl, 6 tbl

FIELD: medicine.

SUBSTANCE: invention describes a method of quantitative evaluation of blood acetic, propionic, isobutyric, butyric, valeric, isocapronic and capronic acids by gas chromatography analysis wherein a blood sample is acidified with 1 % sulphuric acid to pH 2-3, evaluated acids are extracted with isobutyl alcohol volume of which is related to the blood sample volume as 1:1. The protein separation is enabled by centrifugation. 2-3 drops of 0.4 % alkali is added, and the extract is evaporated dry, further the solid residue is added consistently with 1 % sulphuric acid and isobutyl alcohol that is followed with gas chromatography separation of the mixed acids in a capillary column with a flame ionisation detector, and the amount of each acid is evaluated by a calibration diagram.

EFFECT: higher sensitivity and accuracy of the method of quantitative evaluation of acetic, propionic, isobutyric, butyric, valeric, isocapronic and capronic acids if found in blood together.

5 cl, 1 ex, 4 tbl

FIELD: chemistry.

SUBSTANCE: disclosed is a method of detecting unknown substances in body fluids of patients taking narcotic or psychoactive substances. The method involves preparation of three body fluid samples - the first through extraction with re-solution, the second through acid hydrolysis and the third through enzymatic hydrolysis. The first sample undergoes GC/MS analysis at temperature gradient of 15°C/min and data are analysed by comparing with a data base from which features of the unknown substance are detected, specifically spectra with m/z values which coincide with basic ions of the narcotic or psychoactive substance or metabolites and content of the unknown substance in the sample. The second sample undergoes GC/MS analysis at temperature gradient of 25°C/min and the third sample undergoes GC/MS analysis also at temperature gradient of 15°C/min and, if content of the unknown substances in the last two samples is higher than the in the first, the narcotic or psychoactive substance undergoes GC/MS analysis for presence of the unknown substance also at temperature gradient of 15°C/min, and if also not present in the basic substance. Presence of the unknown substance in intact body fluid is also checked, for which a sample of the intact body fluid is prepared via acid hydrolysis and undergoes GC/MS analysis at temperature gradient of 15°C/min and 25°C/min, and if the unknown substance is detected in the intact body fluid, the substance is classified as endogenous, and in the absence of features, an aliquot of the first sample is mixed with the sample of intact body fluid. The sample is prepared via acid hydrolysis of the mixture. The sample undergoes GC/MS analysis at temperature gradient of 15°C/min and 25°C/min. Further, content of the unknown substance is determined from results of both analysis modes and then compared with content of the known substance in the first sample. If content values of the unknown substance in the said three samples coincide, the unknown substance is classified as a new, previously unknown product of metabolism of the basic narcotic or psychoactive substance.

EFFECT: possibility of unique identification of chemical compounds and their fragments in arbitrary combinations while increasing accuracy and rapidness of detection.

4 tbl

FIELD: chemistry.

SUBSTANCE: sodium fluoride is added to an analysed sample in amount of 10% of the mass of the biological object and infused twice in 45 minutes with portions of ethyl acetate, the mass of each of which is twice higher than the mass of the biological material. Separate extractions are combined, filtered through anhydrous sodium sulphate. The solvent from the filtrate is evaporated at temperature 50-60°C. The residue is dissolved in a mixture of hexane-dioxane-propanol-2 solvents. Chromatography is performed in a column with silica gel L 40/100 µ using a hexane-dioxane-propanol-2 mobile phase. The eluate fractions which contain the analysed substance are merged. The eluate is evaporated. The residue is dissolved in a mixture of hexane-dioxane-propanol-2 solvents and the analysed substance is determined via high performance liquid chromatography (HPLC) in a 64x2 mm column filled with Silasorb 600 sorbent using a hexane-dioxane-propanol-2 mobile phase and a UV detector.

EFFECT: invention shortens the duration of detecting tetraethyl thiuram disulphide in blood and increases its sensitivity.

3 tbl, 2 ex

FIELD: medicine.

SUBSTANCE: biological tissue is crushed, processed twice for 30 minutes with portions of ethyl acetate, weight of each twice exceeding weight of a biological object; prepared extractions are combined, filtered through anhydrous sodium sulphate; a solvent is evaporated from the filtrate; the residue is dissolved in acetonitrile; the prepared solution is watered down in the volume ratio 1:4, extracted twice in portions of chloroform, volume of each being equal to volume of a hydrophilic layer; the chloroform extracts are combined, steamed to a dry residue; the residue is dissolved in mixed solvents hexane-dioxane-propanol-2, cleaned in a silica gel column L 40/100µ with using a mobile phase hexane-dioxane-propanol-2; eluate fractions containing an analysed substance are combined; the eluent is evaporated; the residue is dissolved in mixed solvents hexane-dioxane-propanol-2 and analysed by a HELC method in a column of dimensions 64×2 mm filled with the sorbent Silasorb 600 with using a mobile phase hexane-dioxane-propanol-2 and a UV detector.

EFFECT: invention allows higher selectivity, sensitivity and accuracy of biological material analysis for tetramethylthiuramdisulfide.

4 ex, 5 tbl

FIELD: chemistry.

SUBSTANCE: in the method of detecting phenol in aqueous solution via reverse-phase micro-column high-performance liquid chromatography with a preliminary sample preparation step through liquid-liquid extraction with acetonitrile, extraction is carried out at temperature 263±2 K for 30 minutes with ratio of equilibrium volume of water to the organic phase equal to 1:1.

EFFECT: simple and cheap method, high degree of extracting phenol, low detection limit.

1 ex, 3 tbl

FIELD: medicine.

SUBSTANCE: for an assay, 5-7 cm3 of blood is taken, and before extraction the sample is pre-treated with 2 cm3 of 60% sulphuric acid; the extraction process is executed with 30 cm3 of n-hexane once, and gas chromatography is preceded with single treatment of n-hexane extract with 10 cm3 of concentrated sulphuric acid.

EFFECT: invention provides higher reliability of α-HCCH, γ-HCCH test results and twofold reduced time of sample preparation.

1 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: method involves the following steps: a) addition of at least one component selected from potassium carbonate, potassium bicarbonate or potassium hydroxide, to a solution containing 5-(β-methylmercaptoethyl)hydantoin for hydrolysis of 5-(β-methylmercaptoethyl)hydantoin to obtain a solution containing methionine; b) saturation of the solution containing methionine, carbon dioxide with precipitation methionine and separation of precipitated methionine together with separation of a first filtrate; c) division of the first filtrate into a first portion and a second portion, returning the first portion to step (a) and taking the second portion to step (d), where the first portion of the first filtrate may not be present; d) heating the second portion of the first filtrate to temperature above 200°C and pressure of water vapour formed during dwell time sufficient to obtain a filtrate heated to the required temperature, where the filtrate subjected to the said thermal treatment is directly saturated with carbon dioxide with precipitation of methionine and potassium bicarbonate, and the precipitated methionine and potassium bicarbonate are separated while also separating a second filtrate; and e) removal of the second filtrate or returning it to step a).

EFFECT: method increases ultimate yield of the desired methionine product enables attainment of high values of space-time output.

9 cl, 1 tbl, 1 dwg, 1 ex

Up!