the analysis of gas mixtures to determine their qualitative and quantitative composition.

There are chemical, physicochemical, and physical methods of gas analysis. The chemical methods are based on the principle of the absorption of components of a gas mixture by various reagents. For example, carbon dioxide is absorbed by an alkaline solution; oxygen, by an alkaline solution of pyrogallol; unsaturated hydrocarbons, by bromide water. The quantity of a given gas is determined by the reduction in the volume of the mixture to be analyzed. The advantages of chemical methods of gas analysis are the simple design of the analytic instruments (gas analyzers) and the simple procedures for carrying out the analysis. In physicochemical methods of gas analysis, the components of a gas mixture are absorbed by a solution of a suitable reagent. The electrical conductivity, optical density, or other physicochemical properties of the solution are then measured. In order to determine the composition of hydrocarbon mixtures, the method of chromatographic adsorption is widely used. Physical methods of gas analysis are based on the changes in the physical properties of a gas mixture that vary with its composition: density, viscosity, boiling point, thermoconductivity, the emission or absorption of light (spectral analysis), and mass spectra (mass spectroscopy).

The essential advantages of physicochemical and physical methods of gas analysis over chemical methods—faster analysis and the possibility of automatic analysis—make possible their wide application in industry. Gas analysis is used to determine the composition of natural and industrial gases; to control technological processes in the metallurgical, chemical, oil, and gas industries; and to detect toxic, highly inflammable, or explosive gases in the atmosphere at production facilities.