Thin layer chromatography: simple methods of complex analysis

Thin layer chromatography takes a leading place in the issues of quantitative and semi-quantitative analysis of complex pharmaceutical, natural, medical-biological, technological, chemical and many other substances. Thin layer chromatography is also the most accessible method of mass analysis of virtually any class of substances.

This method of separation and analysis of multicomponent systems is widely used in laboratories of the most diverse specificity and orientation: sanitary-epidemiological, veterinary, agrochemical, research, forensic, as well as plant protection stations, standardization centers and forensic medical examination bureau .

The main advantages of thin-layer chromatography based on the movement of the eluent (solvent of the analyte) in the sorbent layer due to the so-called capillary forces are the simplicity and ease of the chromatographic process, the high degree of accuracy of the analysis and the relatively low cost of the necessary equipment.

Thin layer chromatography, having a high degree of sensitivity (low detection threshold) and selectivity, allows to determine 10-20 μg of substances with an accuracy of 7%, which is a very high index. Thin layer chromatography can be of an adsorption and distribution type. The first option is most widely used.

The essence of thin-layer chromatography is the movement of the solvent in the sorbent layer and the spatial distribution of various components, depending on their individual characteristics and properties. The fact is that molecules of different composition and structure are sorbed (deposited) on the solid surface of the chromatographic plate in different ways. Therefore, complex multi-component systems are gradually divided into separate component parts.

Moving at different speeds along the sorbent layer, separate, already separated, components form a chromatogram. Each color spot corresponds to a certain chemical substance. Colorless substances are illuminated with ultraviolet light, under the influence of which many compounds begin to fluoresce, or subjected to treatment with a special coloring reagent.

Among modern analytical methods , gas-liquid chromatography is particularly distinguished. This method of separation and analysis is characterized by using a special non-volatile liquid as a sorbent material, which is wetted with a powdered ceramic material. And as a driving medium, various inert gases are used here . This method is most effective for the study of complex mixtures, which contain hundreds of different components.

Another modern method for studying the composition of complex substances is liquid chromatography. The principal feature of this method is the separation of individual components by using the differences in their distribution between the mobile (eluent) and the immobile (sorbent) phases. This method is most often used in the analysis of a variety of organic compounds (food additives, pesticides, various toxins, etc.). Also this method of chromatographic research is used to control the quality of pharmacological preparations, to determine the content of steroids in biological fluids, amino acid analysis and other.