How gas chromatography works
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The working principle of gas chromatography is that the partition coefficients of the components in the sample are different between the gas phase and the liquid phase of the fixed liquid. When the vaporized sample is carried into the column by the carrier gas, the components are in two of them. Repeated multiple distributions between phases, because the adsorption or dissolving ability of the components is different, the running speed of each component in the column is different. After a certain column length, they are separated from each other and leave the column in sequence. After entering the detector, the generated ion current signal is amplified, and the peaks of each component are drawn on the recorder.
1. Brief introduction of gas chromatography
Gas chromatography is a major scientific and technological achievement in the 1950s. This is a new separation and analysis technology that has been widely used in industry, agriculture, national defense, construction, and scientific research. Gas chromatography can be divided into gas-solid chromatography and gas-liquid chromatography. The word "gas" in gas-solid chromatography means that the mobile phase is a gas, and the word "solid" means that the stationary phase is a solid substance. For example, activated carbon, silica gel, etc. The word "gas" in gas-liquid chromatography means that the mobile phase is a gas, and the word "liquid" means that the stationary phase is a liquid. For example, a layer of squalane is coated on an inert material diatomaceous earth to separate and measure trace amounts of methane, acetylene, propylene, propane and other impurities in pure ethylene.
Second, the characteristics of gas chromatography
Gas chromatography refers to chromatography using a gas as a mobile phase. Since the sample is transported in the gas phase at a high rate, the sample components can be instantaneously balanced between the mobile phase and the stationary phase. In addition, there are many substances that can be selected as the stationary phase, so gas chromatography is a separation analysis method with high analysis speed and high separation efficiency. In recent years, the use of highly sensitive selective detectors has the advantages of high analytical sensitivity and wide application range.
Third, the application of gas chromatography
Most of the raw materials and products in the petrochemical industry can be analyzed by gas chromatography; in the power sector, it can be used to check the latent faults of transformers; in environmental protection work, it can be used to monitor the quality of urban atmosphere and water; It can be used to monitor pesticide residues in crops; it can be used in the commercial sector to test and identify the quality of food; it can be used to study human metabolism and physiology in medicine; it can be used clinically to identify drug poisoning or disease types; The universe can be used to automatically monitor the gas in the sealed chamber of the spacecraft.
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