Thin layer chromatography: simple methods of complex analysis
Thin layer chromatography takes the leading placein questions 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 analysismulticomponent 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 office.
The main advantages of thin-layerchromatography based on the movement of the eluent (solvent analyte) in the layer of sorbent due to the so-called capillary forces, are the simplicity and ease of the chromatographic process, the high degree of accuracy of analysis and the relatively low cost of the necessary equipment.
Thin layer chromatography, having a highdegree 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 the most widely used.
The essence of thin layer chromatographyconsists in the movement of the solvent of the substance in the sorbent layer and in the spatial distribution of the various components, depending on their individual characteristics and properties. The fact is that molecules of different composition and structure are sorbed (precipitated) on the solid surface of the chromatographic plate in different ways. Therefore, complex multicomponent systems are gradually divided into separate component parts.
Moving at different speeds along the layersorbent, separate, already separated, components form a chromatogram. Each color spot corresponds to a specific chemical. Colorless substances are illuminated with ultraviolet, under the influence of which many compounds begin to fluoresce, or are treated with a special coloring reagent.
Among modern analytical methods, especiallygas-liquid chromatography is released. 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 of researchthe composition of complex substances is liquid chromatography. A principal feature of this method is the separation of individual components by using the differences in their distribution between the mobile (eluent) and the stationary (sorbent) phases. This method is most often used in the analysis of various organic compounds (food additives, pesticides, various toxins, etc.). Also this chromatographic method is used to control the quality of pharmacological preparations, to determine the content of steroids in biological fluids, amino acid analysis and other.