(1) Proposed problem The vaporization chamber is the chamber in the inlet, which functions to instantaneously vaporize the liquid sample and then feed it into the column. When analyzing by gas chromatography, the requirements for the vaporization chamber are very high. First, the carrier gas should be sufficiently preheated before entering the vaporization chamber in contact with the sample. The temperature should be close to the vaporization chamber temperature. Therefore, the carrier gas line is generally wound into a coil along the heated vaporizer metal block, or a sufficiently long carrier gas passage is drilled in the metal block to allow the carrier gas to be sufficiently warmed up. Secondly, in order to reduce the diffusion of the sample and reduce the dead volume, it should be ensured that the sample can directly inject the sample into the heating zone, so the inner diameter and the total volume of the vaporization chamber should be as small as possible. Finally, after the carrier gas enters the vaporization chamber, the vaporized sample should be quickly loaded into the column to prevent the sample from reversing into the vaporization chamber and causing the peak to expand. Therefore, choose the appropriate carrier gas pressure and flow rate. So, what are the index parameters of the vaporization chamber? How do these indicators affect the separation measurement? How to set it? (2) Analysis reason The vaporization chamber is a heater chamber that ensures the instantaneous vaporization of the liquid sample, and the cavity is made of stainless steel. As a heater, the vaporization chamber must involve the vaporization temperature. As a "room", there must be a volume and a dead volume. Of course, there are auxiliary devices such as inlets and liners and gaskets. There are also corresponding indicator parameters. General index parameters of the vaporization chamber: 1 selection of vaporization chamber temperature; 2 volume of vaporization chamber; 3 inertness of vaporization chamber; 4 initial temperature of the column; 5 septum purge function. (3) Set the temperature parameter of the solution vaporization chamber. 1 After the volume sample of the vaporization chamber is injected into the vaporization chamber, it must be thoroughly mixed with the carrier gas, otherwise the sample analysis result may be distorted. Therefore, the volume of the vaporization chamber should be small enough to ensure that the peak width of each component of the sample after entering the column is as narrow as possible, thereby reducing the extra-column effect. However, if the volume is too small, the pressure will fluctuate drastically due to the expansion of the sample after vaporization. In severe cases, the sample will be "backflowed", which will increase the extra-column effect. The volume of a common vaporization chamber is 0.2 to 1 mL. 2 The interior of the inertial vaporization chamber of the vaporization chamber should be sufficiently inert, not adsorbing the sample, not catalyzing the decomposition of the sample, and not chemically reacting with the sample. In order to avoid adsorption or catalytic decomposition of the sample in contact with the inner wall of the vaporization chamber metal, a liner is inserted into the stainless steel casing of the vaporization chamber. 3 The initial temperature split injection of the column should eliminate shunt discrimination, and the initial temperature of the column should be as high as possible. To reduce the difference between vaporization temperature and column temperature, the sample undergoes a smaller temperature gradient in the vaporization chamber to avoid partial condensation of the vaporized sample. However, when the column temperature is too high, the partition coefficient becomes small, which is not conducive to separation. Generally, the optimum column temperature is selected through experiments. 4 septum purging function septum purging, mainly used to eliminate the impact of the decomposition of the injection pad or the damage of the mat on the analysis, such as ghost peaks. (4) Case analysis Gas chromatography was used to determine the content of n-hexane and toluene in the mixture. Benzene was used as the internal standard. The effects of the initial temperature of the column and the size of the septum purge gas on retention time, resolution and quantitative results were investigated. Chromatographic conditions: column temperature, initial temperature maintained for 5 min, 15 ° C / min rise to 170 ° C for 1 min; inlet temperature, 220 ° C; hydrogen flame ionization detector temperature, 260 ° C; split ratio 113:1; injection volume It is 0.4 μL. The other chromatographic conditions were unchanged, changing the initial column temperature and the septum purge gas flow. Considering the effects of quantitative results and separation effects, the initial temperature is 40 °C. The size of the septum purge gas has little effect on the separation of the mixture. Usually set to 2 ~ 3mL / min, set high point generally has little effect on the high concentration of components, such as the mixture used in this experiment; however, the septum purge gas is too large, the detection sensitivity is low, not easy A component with a very low concentration is detected. Black Garlic,Cooking Ingredient,Fair Price Wanhe Food Co., Ltd. , http://www.hbblackgarlic.com