SU95037A1 - Method for chromatographic analysis of a multicomponent mixture of organic substances - Google Patents

Description

METHOD OF CHROMATOGRAPHIC ANALYSIS OF A MULTICOMPONENT MIXTURE OF ORGANIC SUBSTANCES

It was announced on November 17, 1950, under No. MNP-244/438250 in the USSR State Technical Committee. Published in Bulletin of Inventions No. 2, 1953.

This invention relates to methods for chromatographic analysis of a multicomponent mixture of organic substances.

Methods are known for chromatographic analysis using solvent washing, in which a mixture of substances separated in an adsorption column into zones is accelerated by passing a solvent through the column, and the separated components, alternately exiting the column from the solvent, are collected in vessels under the column.

The main disadvantage of these methods is the difficulty of directly separating colorless substances.

Optical methods are used to separate the colorless substances at the outlet of the column. The most widely used for this purpose is a flow-through refractometer, sometimes performed as a recorder.

Refractometers of this type do not have sufficient resolving power and their application does not always give satisfactory results.

Interference refractometer can give more reliable results, but its use requires tedious visual observation of the change of interference fringes for a long time (several hours).

The phenomenon of ultraviolet absorption by organic substances is also used to separate colorless substances.

However, the field of application of this method is not great, since the use of ultraviolet rays is possible only for certain substances that have a characteristic adsorption in the ultraviolet.

In the following method, these disadvantages are eliminated. This is achieved by the fact that the qualitative change in the fraction of the test substance is established by using the difference in the integral absorption of the infrared radiation of the spectrum of products that are sequentially selected from the adsorption column into cells that are transparent in the infrared region.

The use of infrared rays can significantly expand

the field of application of this method, since almost all vibrations of complex organic molecules characteristic of their structure lie in the spectral region from 3 to 15 + -4-20 microns.

In the case of using infrared rays for this purpose, it is not necessary to use spectral decomposition.

Organic compounds; various structures provide a J) az personal integral absorption. Thus, by comparing the latter in two cuvettes, it is possible to establish a national, concentration and concentration identity of the substances that fill them, as well as to detect the violation of this identity.

In some cases, it may be useful to use filters in certain parts of the infrared region of the spectrum.

To establish the change of components entering from the washed adsorption column, two flat cells from a material that is transparent in the infrared region are used. One of the cuvettes is filled with a component of the initial washing stage, the second is a flow cell.

Through both cuvettes, identical beams of infrared radiation are directed, which, as they exit the cuvette, act on two heat receivers connected in opposite directions.

With the identity of the substances in both cells, the emf the heat receivers are compensated and the indicating device included in the receiver cost is at zero.

When substances with a modified chemical structure pass through the flow cell, the integral absorption of infrared radiation changes. The balance is broken and the indicating device gives a deviation. For further production. Analysis and collection of the new component of the cuvette are interchanged.

The flow cell is closed and the sample of the initial stage of the new component is retained in it, and the component leaving the adsorption column is directed to the first cell. In this case, the same liquids will appear in both cuvettes and the balance will be restored, the device will show zero until the new component appears in the flow cell, after which the cuvettes should be swapped again, etc.

Instead of these two heat sinks, it is possible to use one in a differential circuit using discontinuous radiation. In this case, the radiation is directed alternately through one or the other cuvette to the thermal receiver. The identity of the cuvette gives a constant emf. receiver to which the indicating device does not respond.

With an impaired identity, a variable emf appears on the receiver. frequency of radiation interruption, which (if necessary, amplified) and affects the indicating device.

The proposed scheme, in addition to using to indicate the change in the components leaving the adsorption column, makes it possible to automate the chromatographic fractionation by automating the change in the designation of the cuvette and the change in the receiving vessels. For this purpose, instead of the indicating device, a relay should be used, which will turn on the motor turning the two-way crane, which guides the liquid from one column into one or another cuvette, and will also include the drive of the receiving vessel conveyor.

Subject invention

Claims (2)

1. A method of chromatographic analysis of a multicomponent mixture of organic substances, characterized in that the qualitative change in the fraction of the test substance is determined by the difference in the integral absorption of the infrared radiation of the spectrum of products sequentially selected from the adsorption column into cells that are transparent in the infrared region. 2. Acceptance of the method according to claim 1, characterized in that.