Principle of Gas Chromatograph:

Gas chromatography is a chromatographic separation analysis method that uses gas as a mobile phase. The vaporized sample is carried by the carrier gas (mobile phase) into the chromatographic column. The stationary phase in the column has different molecular forces from each part of the sample, and the time for each part to flow out of the chromatographic column is different, and the parts are separated from each other. Using an appropriate identification and recording system, make a chromatogram that marks the time and concentration of each part flowing out of the chromatographic column. According to the peak time and sequence indicated in the figure, the compound can be qualitatively analyzed; according to the height and area of ​​the peak, the compound can be quantitatively analyzed. It has the characteristics of high efficiency, high sensitivity, strong selectivity, fast analysis speed, wide application, simple operation and so on. It is suitable for qualitative and quantitative analysis of volatile organic compounds. For non-volatile liquid and solid substances, it can be analyzed through high temperature cracking and gasification. It can be used in conjunction with red light and collection spectroscopy or mass spectrometry. Chromatography is used as a means to separate complex samples to achieve high accuracy. It is an important analytical method for the detection of organic compounds in judicial appraisal.

Principle of liquid chromatograph:

Liquid chromatography is chromatography that uses liquid as the mobile phase. In 1906, the Russian botanist MSTswett added the plant pigment extract to the upper part of the glass column containing calcium carbonate particles, and then eluted the column with petroleum ether. As a result, different pigments were separated in the column to form different Color bands, each color band represents a different pigment. Since then, this type of method is called chromatography. With the development of chromatography technology, chromatography can not only be used to separate colored substances, but also widely used to separate colorless substances, especially organic compounds.