Gas chromatograph uses gas as mobile phase (carrier gas). When the sample is "injected" into the sampler with a micro syringe, it is carried into the packed column or capillary column by the carrier gas.
Because the distribution or adsorption coefficients of the mobile phase (gas phase) and the stationary phase (liquid phase or solid phase) in the chromatographic column are different, under the washing of the carrier gas, the components are repeatedly distributed between the two phases to separate them in the column, and then the components are sequentially detected by a detector connected behind the column according to their physical and chemical characteristics.
Commonly used detectors include: thermal conductivity detector, flame ionization detector, helium ionization detector, ultrasonic detector, photoionization detector, electron capture detector, flame photometric detector, electrochemical detector, mass spectrometry detector, etc. In order to ensure the normal operation of the gas chromatograph and the accuracy and timeliness of the analysis data, it is necessary to maintain the gas chromatograph regularly.
Use steps of gas chromatograph:
1, turn on the regulated power supply.
2, open the nitrogen valve, open the carrier gas switch valve on the purifier, and then check whether there is air leakage, to ensure good air tightness.
3. Adjust the total flow to an appropriate value (measured by a calibrated flowmeter).
4. Adjust the diverter valve so that the diverter flow is the flow required by the experiment (actually measured on the gas path system panel with soap film flowmeter), and the chromatographic column flow is the total flow minus the diverter flow.
5, open the air and hydrogen switch valve, adjust the air and hydrogen flow to the right value.
6. Set the column temperature, inlet temperature and FID detector temperature according to the experimental requirements.
7. Turn on the computer and workstation.
8. When the temperature of FID detector reaches above 150oC, press the FIRE key to ignite the flame of FID detector.
9. Set FID detector sensitivity and output signal attenuation.
10. When the set parameters reach the set values, samples can be injected for analysis.
1 1. After the experiment, turn off the hydrogen and air, blow the chromatographic column clean with nitrogen, and then turn it off.