Precipitation

Precipitation (also precipitation, from the Latin praecipitem - to fall rapidly) is a method of separating and concentrating the components of a mixture by precipitating them from a solution by adding a second solution, called a precipitant.

Precipitation is widely used in analytical chemistry, especially in cases where it is necessary to separate substances with similar properties. The principle of the method is based on the ability of particles of colloidal systems to precipitate when conditions change, for example, when the concentration of a solution changes or when a special reagent is added - a precipitant. A precipitant is a substance capable of forming precipitation with the components of the mixture being analyzed. Typically, salts, acids or bases, as well as other substances capable of forming poorly soluble compounds with the ions of the analyzed components, are used as precipitants.

In immunology, precipitation is used to determine antibodies in blood serum, to identify antigens, and to determine the specificity of antibodies. In these cases, the precipitant represents the antigen with which the antibody must be identified.

Precipitation is one of the methods for diagnosing infectious diseases, often used to identify and isolate pathogens from biological fluids of the body. The method was proposed at the beginning of the 20th century by the German physician G. Schimpfren, but was first used in blood analysis in 1920 by the American physician L. Landrichit. The essence of the method is that, under the influence of electrophoresis or centrifugation, specific antibodies (immunoglobulins) are deposited on the surface of a group of bacterial cells that were previously either stained or seeded. This allows you to determine the type of microorganisms based on their reaction with antibodies. A more complex variant of precipitation is called polyvalent precipitation, and it consists of combining pathogens with the simultaneous manifestation of at least two properties, such as the presence of a capsid, biochemical and biophysical properties, hemolysis, the ability to phagocytose, etc. In modern medicine, precipitation is used not only to diagnose infectious diseases, but also to determine the activity of allergic reactions. Material for analysis can be obtained by drawing blood