16.1 Gas chromatographic instruments Pneumatic system, sampling system, column separation system, temperature control system, various detectors
16.2 Gas chromatography stationary phase Gas-solid chromatography stationary phase (adsorbent), gas-liquid chromatography stationary phase (carrier + stationary solution)
16.3 Gas chromatography separation analysis conditions Column length, carrier gas and its flow rate, packed particles, column temperature, injection volume and injection method
16.4 Qualitative analysis Retention time, empirical law, retention index, dual column qualitative, instrument qualitative
16.5 Quantitative analysis Correction factor, normalization method, external standard method, internal standard method
16.6 Introduction to Capillary Chromatography Capillary classification and characteristics
Gas chromatography process: the sample of the analyte is evaporated into gas and injected into the top of the column of the chromatographic separation column. The sample steam is brought into the column for separation. The separation principle is based on the adsorption-desorption (gas-solid chromatography) and distribution (gas-liquid chromatography) of the analyte between the gas phase and the stationary phase. Therefore, gas chromatography can be divided into gas-solid chromatography and gas-liquid chromatography.
Gas-solid chromatography: the use of different substances on the solid adsorbent for different physical adsorption-desorption capabilities to achieve the separation of substances. Due to the semi-permanent retention of active (or polar) molecules on these adsorbents (the adsorption-desorption process is non-linear), the chromatographic peaks are severely tailed, so gas-solid chromatography applications are limited. Only suitable for the separation and analysis of lower molecular weight and low boiling gas components.
Gas-liquid chromatography: usually directly called gas chromatography. It uses the principle of distribution of the analyte between the gas mobile phase and the liquid stationary phase fixed on the surface of an inert solid to achieve separation. In 1941, Martin and Synge (which also made great contributions to liquid-liquid distribution chromatography) proposed the concept of gas-liquid distribution chromatography. Eleven years later, in 1952, Jones and Martin demonstrated the method through experiments; three years later, in 1955, the first gas chromatograph came out. In 1985, an estimated 100,000 instruments were put into use! Now? Can't tell.
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