The way physico-chemical analysis of materials
(57) Abstract:Use: for the quantitative gas chromatographic separation of high-boiling components of crude oil. The essence: if you have a low residual pressure, ensuring compliance with proportion to the partial pressure of the analyzed component from its mole fraction in the separating liquid, under conditions of programmed temperature increase carry out the separation of high-boiling components of crude oil. The technical result of the invention consists in the expansion of the range separating liquids at high temperatures and reducing erosion of the chromatographic bands of the components of the analyzed material. The invention relates to research or analysis of materials, in particular to gas chromatography for the quantitative determination of high-boiling components of crude oil.There is a method for physical-chemical separation of the components of the mobile phase as it moves along the stationary phase. The method consists in the fact that through the column passed a steady stream virtually no adsorbiruyuschee (or not soluble in the stationary liquid) gas and the carrier gas at the entrance of the column enter naibolee adsorbiruya (or the least soluble component of this mixture, further pure carrier gas, then stronger adsorbiruya component, again the carrier gas, etc. of the Zone output (s) of the components in the chromatogram are separated carrier gas [1, 512 S., 2nd paragraph].The disadvantage of this method is that its application is limited to separation of high-boiling components, which are strongly adsorbed on the surface of the carrier.Closest to the proposed invention, where partially eliminated the above-mentioned disadvantage of the method is gas chromatography with programmable temperature. The known method of physico-chemical analysis of the materials, including the separation of components of the mobile phase as it moves along the stationary phase with programmable temperature used for the analysis of high-boiling petroleum products [2, S. 6, paragraph 2].The known method also has its drawbacks associated mainly with volatility separating liquids at high temperatures [1, C. 513, last paragraph].The task of the invention is the expansion of the range separating the liquid (stationary phase) at high temperatures and reducing erosion of the chromatographic bands of the analyzed mixture.The main parameter of the chromatographic strip - characteristic retention is associated with values of thermodynamic functions of dissolution (or adsorption) of the analyzed component. Thermodynamic function of dissolution (adsorption), in turn, connected c pressure. It is known that in the area of low pressure (shares or more mm Hg) the shape of the curve isotherm dissolution approaching linear, that is observed is proportional to the dependence of the partial pressure of the analyzed component from its mole fraction in the separating fluid and the dissolution rate (evaporation) is constant for a given component [1, C. 418, last paragraph]. At a constant flow rate of gas in the column flow chromatographic bands is also constant. This speed is greater, the worse adsorbed (or dissolve) the analyzed component, and the less, the better it is adsorbed (or dissolves). Therefore, chromatographies the awns, that provides a clear separation. This is a significant advantage of the present invention from the known method in which the separation of components is carried out in the condensed state at a pressure slightly above atmospheric (800-850 mm Hg). At low residual pressures (three orders of magnitude below atmospheric share or more mm Hg) in the column of the chromatograph partial pressure of the dissolved component is determined only by the chemical nature of the analyzed component and does not depend on the nature of the separated liquid (stationary phase), which can significantly extend the range of these liquids. In this second essential difference of the present invention. Since each band in the gas phase moves along the column at a constant speed, the distribution of the partial pressure created at the entrance of the column at the inlet samples, will move to the exit from the column without changing the (overlapping strips of the other components) and the chromatographic strip the analyzed component will be recorded by the detector without dilution.An example of the method. The implementation of the method is to pre-determine the equilibrium pressure at which PR is forest pressure, when observed proportional dependence of the partial pressure of the analyzed component from its mole fraction, use the curves of adsorption isotherms of the analyzed components. The corresponding isotherms are found in the literature or determined by the statistical method and the difference between the entered number of the analyzed component and remaining in the equilibrium gas phase (method of evaporation of liquids from the vacuum microburette, gas volumetric method). Statistical methods used in the study of adsorption of individual gases or vapors in vacuum installations in which the adsorbent pre-pumped by heating to remove the previously adsorbed components. The presence of extraneous components reduces the amount of adsorption and slows down the balance.Installation to determine the equilibrium pressure with vacuum microburette from which the vapor of the liquid component is applied to the ampoule with the separating liquid. The amount of dissolved component is measured by the loss of this component in microburette minus the number of the component remaining in the gas space above the separating liquid. The volume of this space is pre-nomerami. In volumetric gas method uses the same principle, but the gas source is a gas burette [1, S. 432, last paragraph]. For example, low equilibrium pressure at which the observed proportional dependence of the partial pressure of the analyzed component from its mole fraction for benzene is 0.2 mm Hg), and carbon tetrachloride - 0.45 mm [1, C. 418, Fig. XVI.l].Known design chromatograph [1, S. 514, Fig.1], in which the carrier gas from the cylinder through the valve enters the column, after exiting the column, the gas passes the detector. A detector that registers the change of thermal conductivity of the gas on the heated metal threads, is more sensitive and therefore more preferable [ibid, S. 514]. The volumetric rate of gas is measured after the output of the detector by the rheometer. For the quantitative determination of benzene and its homologues chromatographic column through the exit of the rheometer is connected to a vacuum pump that creates and supports the analysis vacuum (residual pressure) in the column equal to 0.2 mm Hg. The approximate conditions of the analysis (except pressure) different components of crude oil are shown in table [2, C. 134, PL.1]. In the rest of the course of the analysis area is the development of a chromatographic column to a residual pressure (fraction mm Hg) allows you to extend the range of the separating liquid (stationary phase) at high temperature and provides a more distinct separation of components by reducing erosion (overlay) of the chromatographic bands of the analyzed mixture.Literature
1. J. I. Gerasimov, V. P. Drawing, E. N. Eremin, etc. a Course in physical chemistry. Volume 1. Edition 2. M.: Chemistry, 1969, 592 S.2. M. S. Vigdergauz. Gas chromatography as a method of research oil. M.: Nauka, 1973, 256 S. The way physico-chemical analysis of materials, including separation in the chromatographic column components of the mobile phase as it moves along the stationary phase with a programmable temperature, characterized in that the separation of the components produced at low residual pressure, ensuring compliance with proportion to the partial pressure of the analyzed component from its mole fraction in the separating liquid.
FIELD: chemical engineering; medical engineering.
SUBSTANCE: method involves plotting two chromatograms one of which is based on radioactivity (No 1) and the other one on ultraviolet absorption (No 2) or on radioactivity (No 1) and on fluorescence (No 2) and chromatogram specific relative to ultraviolet absorption (No 3) or relative to fluorescence (No 3). Material quality is estimated to be the more high the more close studied labeled compound peak shape is to trapezoid shape on the third chromatogram.
EFFECT: high accuracy of the method.
FIELD: analytical chemistry, ecology, in particular controlling of environmental air.
SUBSTANCE: claimed method includes aspiration if air sample through chemosorbtive medium, elution of formed dimethylamine salt, eluate closure with alkali, and gas chromatography analysis of gas phase with flame-ionization detection. Dimethylamine salt elution from adsorbent is carried out with 1 cm3 of distillated water; closured with alkali eluate is held in thermostat for 5 min; and as filling in separating chromatography column chromosorb 103, containing 5 % of PEG-20000 and treated with 20 % hexamethyldisilazane solution is used.
EFFECT: method for dimethylamine detection with improved sensibility and accuracy.
FIELD: chemical industry.
SUBSTANCE: during process of taking sample from technological pipe-line, absorption of water vapors and nitrogen oxides (II) and (IV) are conducted simultaneously. For the purpose the chemical agents are used which don't absorb nitrogen oxide and don't react with it. Chromatographic measurement of volume fraction of nitrogen oxide (I) is carried out by means of industrial chromatograph having heat-conductance detector by using column of thickness of 5 m and diameter of 3 mm. The column is filled with polysorbent; temperature of column's thermostat is 20-30 C and temperature of evaporator is 100C. Hydrogen is used as a gas-carrier. Concentrations of nitrogen oxide, measured by the method, belong to range of 0, 05-0, 50% of volume fraction. Method excludes aggressive affect of corrosion-active components on sensitive parts of chromatograph. Method can be used under industrial conditions for revealing factors influencing process of forming of nitrogen oxide at the stage of catalytic oxidation of ammonia and searching for optimal conditions for minimizing effluent of ammonia into atmosphere.
EFFECT: high reproduction; simplification; improved efficiency of operation.
FIELD: oil and gas production.
SUBSTANCE: aim of invention is estimating expectations for oil and gas of oil-source rock areas. For that aim, sampled rock is treated to isolate organic substance soluble in organic solvents, after which organic substance is chromatographed to detect 4-methyldibenzothiophene and 1-methyldibenzothiophene. When ratio of 4- to 1-isomer exceeds 0.9 rock is regarded as ripened.
EFFECT: increased determination reliability and rapidity.
SUBSTANCE: in the method, hard carrier with system of narrow pores and channels is kept under temperature below height of potential barriers for movement of at least one type of separated molecules.
EFFECT: higher efficiency.
FIELD: investigating or analyzing materials.
SUBSTANCE: gas analyzer comprises chromatographic columns, detectors, unit for preparing air mounted inside the thermostat, unit for control and processing signals, member for sampling, switches of gas flows, pump for pumping gas mixture, and separating passages connected in parallel and provided with the check valve interposed between them. Each of the separating passages is made of absorbing and separating chromatographic columns connected in series, and the pump is connected to the input of the gas line through the electric valve. The gas analyzer can be made of two separating passages and low pressure chromatographic columns.
EFFECT: enhanced quality of analyzing.
2 cl, 1 dwg, 1 ex
FIELD: analytical methods.
SUBSTANCE: to determine methyl alcohol in water, sample to be assayed is preliminarily subjected to distillation with sulfuric acid added in amount required to provide its concentration in mixture to be distilled c(1/2 H2SO4) = 0.002 M, while strippings constitute 6-7% of the volume of sample. Stripped liquid is thrice rinsed with hexane or Nefras at 1:1 hexane (Nefras)-to-strippings ratio. Rinsed material is then introduced into packed column filled with diatomite modified with 1,2,3-tris(β-cyanoethoxy)propane having deposited fixed phase thereon, which phase is prepared by way of consecutively keeping glycerol each time for 4 h at ambient temperature, 100°C, 130°C, 160°C, and 200°C, and then for 8 h at 230°C and for 40 h at 200°C under nitrogen bubbling conditions. Calculation of methanol content is performed taking into consideration calibrating coefficient.
EFFECT: enabled determination of small concentrations of methyl alcohol in water with sufficient selectivity and reliability.
2 cl, 2 tbl, 6 ex
FIELD: analytical chemistry.
SUBSTANCE: invention relates to method for quantitative determination of thiotriazoline and pyracetam in complex drugs by high performance chromatography, wherein silicagel with grafted 3-(chlorodimethyl)-propyl-N-dodecylcarbamate having particle size of 5 mum is used as sorbent; and degassed 0.05 M aqueous solution of potassium dihydrophosphate is used as mobile phase. Mobile phase velocity is 1 ml/min, and column temperature is 30°C. Method of present invention makes it possible to determine content of two abovementioned active ingredients simultaneously.
EFFECT: simplified process of sample preparation.
3 ex, 3 tbl
FIELD: biotechnology, in particular content determination of polymer chitosan molecules, chitosan-chitine polymer molecules and molecules of chitosan-protein complex in finished form of chitosan.
SUBSTANCE: claimed method includes application of high performance chromatography column filled with polyvinylbenzene sorbent with refractometer detector. As eluent and for dissolving of chitosan preparation samples acetic acid aqueous solution is used. Chain-length distribution is determined on the base of first chromatography peak, and polymer molecular content is calculated on the base of area of first, second and third chromatography peaks, divided up to zero line and belonging to polymer chitosan molecules, chitosan-chitine polymer molecules and molecules of chitosan-protein complex, respectively. To calculate chain-length distribution of polymer chitosan molecules separately calibration curve is plotted using dextran polymer standards.
EFFECT: new effective method for determination of polymer chitosan molecules in chitosan preparations.
4 cl, 3 dwg
FIELD: the invention refers to laboratory chromatographic devices for conducting high-speed chromatographic analysis.
SUBSTANCE: the express-chromatron has an injector, a chromatographic column located in a thermostat, a detector, an amplifier of the signal of the detector, an analog-digital converter, a control system, a pneumatic system. The column is fulfilled either in the shape of a short capillary column or either in the shape of a polycapillary column. The injector is fulfilled with possibility of introduction of the test for the time of 5-50 ms. The detector and the amplifier of its signal are fulfilled with possibility of ensuring constant time of no worse then 10-3 sec. The analog-digital converter is fulfilled with possibility of ensuring speed of no less then 200 measurements in a second.
EFFECT: ensures conducting high-speed chromatographic analysis.
11 cl, 2 dwg