What is chromatography?

What is chromatography?

Chromatography

The word "chromatography" means "colored letter", but it is wrong because it often does not include paper, ink, color or letter.

The method was proposed in 1903 by Michael Semenovich Color.

M.C. Color used chromatographic methods to separate plant pigments. For the separation of chlorophylls, Color filled the glass tube, while in the surface layers of the ion column there was an intense green ring that quickly formed a yellow stone on the lower edge.

The result of the separation, namely, the sequence of different colour areas, Color called the chromatograph. To separate the pigments, Color used more than 100 different adsorbents, worked in detail on the separation technique and proposed different options for its method.

A few decades later, scientists came up with new types of chromatography, various sorbents and chromatographic techniques, and it is well known that one of the discoveries of a new type of chromatography is linked to our country. In 1938, an article by N.A. Izmaylov and M. S. Schreiber, "Coil-chromatographic analysis and its application in pharmation",3 was published in the journal "Pharmacy", which gave rise to a new direction in chromatography, a thin layer chromatography.

Recently, there have been a number of reports from respected Russian chemists that, almost in parallel with Western scientists, the first work in the field of analytical gas chromatography was carried out in 1940 by Soviet researchers M. M. Senyavin, N. M. Tulkertaub, A.A. Zhuhovitzki and D.A. Vakhirev. These were work on gas adsorption, carried out well before the well-known publication of A. James and A. Martin in 1952, from which the history of gas chromatography 4 was officially calculated.

According to expert estimates, chromatography is among the 20 outstanding discoveries of the past century that have most transformed science and, through it, determined the state of technology and industry, civilizations in general. Although in education and occupation, Color was a botanist, its results are so significant to all natural sciences that the Federation of European Chemical Societies, for example, gives the name Color along with four other Russian names.

The chromatography method is based on the dynamic distribution of substances between two phases, fixed . Depending on the nature of the interaction between components of the mixture with fixed and mobile phases and individual properties, the components are moving at different speeds, thus separating them from each other. The basic terms and concepts relating to chromatography, as well as their areas of application, have been systematized and harmonized by the IUPAC Special Commission. According to IUPAC recommendations, the term "chromatography" has three meanings and is used to refer to a special section of chemical science, process and method 6.

There are different ways to classify chromatographic methods: the physical state of the mobile phase et al. Modern chromatography has many varieties, the most popular of them, which will help you get a better idea of the process. We have tried to explain them in very simple language.

Basic chromatography

In essence, chromatography involves the interaction of two different phases, a chemical compound in the same state of the substance.

The moving connection is known as the mobile phase, while the stable substance is called the stationary phase. The components of the mobile phase are separated when it moves through the stationary phase. The chemicals can then analyse the individual components one after another.

4 different types of chromatography

There are several types of chromatography, each of which has its own type of mobile and fixed phase. Although the basic principle remains the same, the way the different components interact with the mobile phase and the stationary phase may vary according to the chromatographic method used.

Here is a list of the main types of chromatography that will help you get a better idea of the process. We tried to explain them in very simple language.

1. Paper chromatography

Paper chromatography is the most common and simple analytical method for separating and detecting colour components, such as pigments; although modern laboratories use thin chromatography more frequently, it is still a powerful educational tool.

In this method, the drop of the sample mixture is suspended in such a way that the ink stain does not affect the solvent and remains slightly above it.

After a while, the solvent by capillary force, because the solvent moves up, it attracts ink dyes with it.

When it rises, we see different colors on filter paper. These colors represent different dyes present in ink. Since different dyes have different levels of solubility and move at different speeds when the solvent rises, we see different colour bands at different heights.

This is how paper chromatography is used to separate different components of ink. In some cases, mixtures do not contain colour components, so chemicals add other substances for identification.

2. Toncosloi chromatography

Toncosloy chromatography is very similar to paper chromatography. The main difference is that instead of a piece of paper, we have a piece of glass covered with a layer of silicagel. In this method, drops of the solution of the measured mixture are applied to the lower edge of the subject glass with the silicagel, parallel to the lower edge and distance from it so that the drops do not sink into the eluent.

When they dry, the subject glass at the lower edge is sunk into the solvent layer to the upper edge of the glass; the various compounds in the mixture move up the layer of the silicagel at different speeds in the form of spots; these separated stains are then visualized in ultraviolet light.

In some cases, chemical processes are used to visualize stains: for example, sulphuric acid is tanning most organic components, leaving a dark stain on the subject glass; this is a simple and fast technique for separating mixtures of organic compounds; it is often used to identify pigments, analyse dye compositions in fibres and identify insecticides or pesticides in food products.

Compared to paper chromatography, thin layer chromatography results in better separation.

3. Gas chromatography

Gas chromatography is used to separate mixtures of volatile organic compounds.

Usually the amount of gas sample is small, in order of microliters. A moving phase in gas chromatography is called a carrier gas. Because we don't want a gas carrier to contain a fixed phase of a thin layer of liquid or polymer on an inert solid substrate.

The separation of the components in the mixture comes from the difference in their boiling temperatures – the compounds with a low boiling point are moving faster than the components with a higher boiling point, as well as the polarity and other specific interactions with the mobile phase.

This results in each component elucidating at different times, also called the retention time of the component. By comparing the retention times of the separated components with the retention times of known compounds, chemists can analyse the compounds in the mixture.

4. Liquid chromatography

Liquid chromatography

The column usually consists of a metal or plastic tube filled with tiny sorbent particles with a defined surface chemistry. Since each compound in the mixture reacts differently with the sorbent, it moves in a column with different speeds, thus separating them from each other. The selection of the rolling phase composition depends on the properties of the stationary phase and the substances being analysed.

The chemicals run a series of tests and work out a separation method to find the best liquid chromatography method for a mixture that can provide an ideal spade separation.

Here's a quick comparison of the four main types of chromatography:

Modular phase Description Paper chromatography Water or organic solvent Paperdistinguishing through distribution processes Toncosloic chromatography Organic solvent Aluminium oxide or silicagel
Modular phase Description Paper chromatography Water or organic solvent Paperdistinguishing through distribution processes Toncosloic chromatography Organic solvent Aluminium oxide or silicagel

Application

Several Nobel Prizes were awarded for chromatography research or chromatographic research.

More than 60 per cent of chemical research around the world is done using different types of chromatography. Modern chromatographs can separate and identify several hundred compounds per analysis. Some chromatographic detectors can determine the amount of substance at ppb scale.

As a result of these advantages, chromatography is now widely used in

  • Forensics: Analysis of samples obtained from crime scenes Monitoring of pollution: to detect small concentrations of hazardous pollutants in air and water. Medical field: in the process of production and quality control of biological and pharmaceutical products. Food industry: detection of deterioration in food products, determination of food quality and monitoring of food additives. Legal action: to determine the availability of alcohol in blood and cocaine in urine. Radiochemistry: for the characterization of radioactive swords and determination of radiochemical purity.

Chromatography is also used for DNA and bioinformatics, clinical diagnosis of diseases and disorders, and for various research purposes.

1E.M. Senchenkov, Michael Semenovich Color, Moscow: Publication of Science, 19732M.S. Color of Chromatographic Adsorption Analysis, Selected Works, under Rev. A.A. Richter and T.A. Krasnoselski. First edition of the USSR. 19463 Izmail N.A., Schrayber M. S. S. S. S. Cromatographic Method of Analysis and its Application in Pharmation. Pharmation. 1938, No. 3, c.1-74 R. Hamizov, V.F. Celemenev. Who opened the gas chromatography? //Sorbial and chromatographic processes. 2018. T. No. 2. C 128-1305 "Stay years of chromatography" V. A. Davankov, Y. I. Yashin ////Vestnik of R. R., 2003, vol. 73, No. 7, 637-64Nomenclature for Chrommato.

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