Chinese name: chromatography mbth: Introduction to chromatography, classification, thin layer chromatography, gas chromatography, high performance liquid chromatography, supercritical fluid chromatography. This paper introduces that chromatography can solve the separation and analysis of complex multicomponent mixtures such as homologues and isomers with similar physical constants and chemical properties, and can not only identify compounds, but also quantitatively determine them. Moreover, the instruments and equipment of chromatography are not complicated and easy to operate. In addition, it also has the advantages of high separation efficiency, high sensitivity, fast analysis speed, accurate quantitative results and easy automation. It has become an analytical method for organic matter, petroleum products, environmental protection and other automotive materials and related fields. Classification chromatography can be divided into gas chromatography, liquid chromatography, thin layer chromatography, gel chromatography, supercritical fluid chromatography and so on according to the states of mobile phase and stationary phase. Chromatograms are divided into analytical chromatograms, preparative chromatograms and process chromatograms. Make different choices according to different application fields. According to the classification of two-phase state, see table. Thin-layer chromatography Thin-layer chromatography is a plane chromatography. The mixture to be separated is spotted on a thin sheet evenly coated with stationary phase, developed in a closed chromatographic tank with a suitable developing agent, and the separated compound is developed on the thin layer to form a chromatographic band. Characteristics of TLC: simple method, simple operation, no need for special equipment except densitometer, good separation effect and short time, and multiple samples can be separated on one plate at the same time. All kinds of organic and inorganic compounds can be separated except low-boiling substances. Used for separation and analysis of organic matter. The sample dosage is usually several to several hundred micrograms, which is a practical and effective micro-separation and analysis method. Gas chromatography is abbreviated as GC. It is a separation method founded by British biochemist A.T.P. Martin and others on the basis of studying liquid-liquid partition chromatography in 1952. It can analyze and separate complex multicomponent mixtures. Gas chromatography is a kind of chromatography with gas as mobile phase, which is used to determine substances or compounds that can be gasified or converted into gas. It can also be divided into gas-solid chromatography (GSC) and gas-liquid chromatography (GLC): the former mainly separates some permanent gases and low-boiling compounds; The analysis object of the latter is mainly organic matter that can be gasified. At present, gas chromatography has become an analytical method with fast analysis speed, high sensitivity and wide application range. Such as gas chromatography and mass spectrometry (GC-MS), gas chromatography and Fourier infrared spectroscopy (GC-FTIR), gas chromatography and atomic emission spectroscopy (GC-AES). It is mainly used for the separation and analysis of oil, paint, plastic and other related chemical components in the application of automotive materials. High performance liquid chromatography (HPLC), also known as high pressure liquid chromatography, is a new separation and analysis technology with liquid as mobile phase developed in the late 1960s and early 1970s. It uses the classical principle of liquid column chromatography, introduces the theory of gas chromatography, adopts high-pressure infusion pump, high-efficiency separation column, high-sensitivity detector and computer control system, and has the characteristics of high separation efficiency, fast analysis speed, high detection sensitivity (the lowest can reach 10g/mL), wide selection range of mobile phase, convenient preparation of pure products from the effluent components, and wide application. It has become a brand-new separation technology in today's chromatography. The main disadvantages of high performance liquid chromatography are expensive equipment and strict operation. High performance liquid chromatography (HPLC) has been applied to the analysis of organic matter in automotive materials. Supercritical fluid chromatography; It is a chromatographic method with supercritical fluid as mobile phase. The so-called supercritical fluid refers to some substances that are neither gas nor liquid, and their physical properties are between gas and liquid. Supercritical fluid chromatography is a brand-new chromatographic technology developed in 1980s. Because it has the advantages that gas phase and liquid phase do not have, it can separate and analyze some objects that gas phase and liquid phase can not solve, so it is widely used and develops very rapidly. It is estimated that up to now, about 25% of all separated substances involve refractory substances, and satisfactory results can be obtained by supercritical fluid chromatography. Supercritical fluid chromatography can be used to separate and analyze the chemical composition of oil in automobile materials.