Device for quantitative analysis of components not isolated on chromatogram

FIELD: physics.

SUBSTANCE: proposed device comprises unit of carrier gas preparation, sample feed assembly, two chromatographic columns, DC source, detector and results processing system, all said units being connected in series. Note here that one of the columns is connected with sample feed assembly, while the other one is connected with detector. Note also that second column is mounted between two flat parallel electrodes connected to DC source.

EFFECT: higher efficiency and selectivity.

1 tbl, 1 dwg

 

The invention relates to gas chromatography and can be used for the quantitative analysis of complex mixtures of various substances of natural and anthropogenic origin in such industries as chemical, oil, gas, petrochemical, medicine, ecology and other

The known device for the quantitative analysis of unattributed on the chromatogram of the components using the reaction gas chromatography, contains a special reactor, periodically included between the separation column and the detector to remove the result of a specific chemical reaction of one or more undivided on the chromatogram of the components. Concentration unattributed components is determined by the ratio of the chromatographic peak area before and after the reaction (see Berezkin V.G. Analytical reaction gas chromatography. - M.: Nauka, 1966. 184 C.).

Also known device using a gas schemes chromatographs with switching columns filled with different sorbents. This chromatographic peak with unattributed components of one column is sent to another column, providing the separation of the studied components on separate chromatographic peaks (see Holbert K.A., Vigdergauz, MS Introduction in gas chromatography: Ed. 3rd revised and enlarged extra - M.: Chem which I 1990. 352 S.).

The disadvantage of these devices is the need for preliminary identification unattributed on the chromatogram of components to choose an effective reagent for chemical removal or appropriate sorbent for repeated chromatographic separation.

Closest to the invention, the set of essential features for a device for the quantitative analysis of unattributed on the chromatogram of components that contains one United block of training with the carrier gas inlet node samples, two chromatographic column, a constant current source, a detector and a processing system for analysis. In this device one of the speakers connected to the input node of the sample, is the basis of the separation of the sample components, and the second, coupled with the detector, is optional. Moreover, an additional column is made of quartz capillary (length 3 m, an inner diameter of 0.35 mm), on the inner wall of which is coated with liquid stationary phase 4,4'-p-aryloxyalkanoic under the influence of an electric field generated coaxial arrangement of the electrodes, one of which is in the form of a thin wire is located inside a quartz capillary, and the second in the form of a conductive film applied to its outer surface (see Watabe is., Hobo T, Suzuki S. // J.Chromatogr, 1982. V.249. p.209-220).

The disadvantages of the known devices are:

1. The violation of the homogeneity of the coating of the inner wall of the quartz capillary stationary phase and the intensity of the electric field due to the arbitrary location of the wire inside a quartz capillary, which leads to reduced efficiency and selectivity of the chromatographic separation of the investigated mixtures.

2. The design complexity is the need of a coaxial arrangement of the electrodes, which leads to the impossibility of effective separation on columns of greater length.

The objective of the invention is to simplify the design and the ability to perform quantitative analysis under the action of electric field on tokoprovodyaschym capillary columns.

This problem is solved due to the fact that the device for the quantitative analysis of unattributed on the chromatogram of components that contains one United block of training with the carrier gas inlet node samples, two chromatographic column, a constant current source, a detector and a processing system analysis, in which one of the columns is connected to the input node of the sample, and the second is connected with the detector and is made of non-conductive electrical shock, capillary, the inner wall of which is coated with p the polar liquid phase, under the influence of an electric field, according to the invention the second column is installed between two flat, parallel spaced electrodes, the distance between which is equal to the outside diameter quartz capillary.

When the task is created the technical result consists in increasing the efficiency and selectivity of the chromatographic separation by simplifying the design and replacement of the coaxial electrode on the plane.

The invention is illustrated in the drawing.

The figure schematically shows a device for the quantitative analysis of unattributed on the chromatogram of components, which contains gas treatment unit carrier 1, the input node of the sample 2, the first separation column 3, the second additional column 4, a detector 5, the processing system analysis 6, plane-parallel electrodes 7, the distance between which is equal to the outside diameter quartz capillary, the constant current source 8.

Device for the quantitative analysis of unattributed on the chromatogram of the components is as follows.

The analyzed mixture containing acetone, ethanol and propanol, dosed in the node input samples 2 and chromatographic on two serially connected columns 3 and 4 using a carrier gas from the preparation unit 1, and is Alonso 4 (L=3,0 m, dc=0.25 mm, stationary phase - p,p'-methoxyethoxyethoxy) are affected by the electric field from the constant current source 8 (500-1000) two plane-parallel electrode 7 with dimensions 200×200 mm, the distance between which is equal to the outer diameter of the capillary. The signal from the detector is fed into the processing system analysis 6 (software package Multichrom, version 1,5x with your computer).

Under the action of electric current is irreversible sorption of some part of the sorbate molecules. The degree of sorption depends on the electric field intensity, nature of the used liquid crystal, the nature and geometry of the sorbate molecules. At constant field strength, the degree of adsorption is constant and does not depend on the sample volume and the imposition of other compounds. Using the effect of sorption, in the famous prototype of the described algorithm quantitative analysis unattributed on the chromatogram of the components. For this study mixture was analyzed at least five times at different volumes of samples and built a plot of the square of the total peak unattributed components (Q) of the sample volume (V). Under the influence of the electric field and the effect of sorption dependence of Q=f(V) has the form of a polygonal curve. The number of fractures corresponds to the number of unattributed components. The undivided concentration on the chromatogram of the components (C i) was calculated by the equation of internal normalization excluding calibration factors for individual components.

where tgαi- the slope of the i-th plot the polyline curve;andthe chromatographic peak area corresponding to the beginning and end of the i-th plot the polyline curve.

The table shows the results of the quantitative analysis of model mixtures containing acetone, propanol and ethanol, which suiryudan on the chromatogram in the form of one lone peak.

The results of the quantitative analysis of the mixture model
ComponentsCi(East), % of the mass.Ci(ISM), % of the mass.δi, %
Acetone26,031,019,2
Propanol22,028,027,3
Ethanol52,041,0of 21.2

The true concentration for which mponents mixture model C i(East)was determined by gravimetric method by weighing the individual components of the brand "chemically pure" at the laboratory analytical balance of POWER - 200.

Measured on the proposed device the concentration of Ci(ISM)determined by the equation (1).

The accuracy δidefined by the equation

From the table it is seen that the accuracy of the concentration measurements unattributed on the chromatogram of the components does not exceed 30%, which is comparable with the accuracy of quantitative analysis without taking into account the sensitivity coefficients, when the accuracy can reach 40 percent or more (see Analytical chromatography / Cigacice, Van, Saurav and others - M.: Chemistry, 1993. S-426).

The use of the device for the quantitative analysis of unattributed on the chromatogram of the components will allow to determine the concentration of unknown components in the event of incomplete separation with other components that will enhance the efficiency and selectivity of the chromatographic separation in the analysis of complex mixtures of substances.

In addition, the use of the device for the quantitative analysis of unattributed on the chromatogram of the components will increase the number of defined components in the analyzed mixtures.

Give the TWT for the quantitative analysis of unattributed on the chromatogram of the components, contains one United block of training with the carrier gas inlet node samples, two chromatographic column, a constant current source, a detector and a processing system analysis, in which one column is connected to the input node of the sample, and the second is connected with the detector, and the second column is made of non-conductive electrical shock, capillary, the inner wall of which is coated with a polar stationary liquid phase, under the action of an electric field, wherein the second column is installed between two flat parallel spaced electrodes, the distance between which is equal to the outside diameter of the quartz capillary.



 

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1 tbl, 1 dwg

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