Gas chromatography operating procedures and precautions:

　　

　　1.Gas chromatograph manufactureroperating procedure

　　

1.1 Open the valve of the carrier gas cylinder counterclockwise, and the high-pressure gauge on the pressure reducing valve indicates the pressure of the stored gas in the high-pressure cylinder.

　　

1.2. Rotate the pressure reducing adjusting screw clockwise to indicate the required pressure on the low-pressure gauge.

　　

1.3 Turn on the main power switch of the host, the touch sensitive fluorescent screen display instrument of the host is self checking, and the blower motor in the column room is running.

　　

1.4 Open the computer connected to the gas chromatograph and run the gas chromatograph software. After the software is successfully connected to the instrument, the experiment can be conducted.

　　

1.5 Set the carrier gas flow rate, detector temperature, injection port temperature, initial temperature of the column box, and heating program in the working software of the gas chromatograph manufacturer. After setting, the temperature in each area starts to rise towards the set value. When the temperature reaches the set value, the READY light will turn on.

　　

1.6 Check if the instrument baseline is stable, and after the baseline is flat, the sample can be injected for testing.

　　

After the experiment is completed, turn off the detector power first, then stop heating. When the temperature of the chromatographic column and injection port drops below 80 ℃, turn off the power switch of the chromatograph and the computer power in sequence. Finally, turn off the carrier gas pressure reducing valve and the main valve.

　　

1.8 Register the use of instruments, organize and clean the laboratory, and ensure safety before leaving

　　

2. Setting of testing conditions for gas chromatograph manufacturers:

　　

The setting of chromatographic conditions should be based on the different properties of different compounds, and generally polar compounds should choose polar columns. Choose non-polar columns for non-polar compounds. The determination of chromatographic column temperature is mainly determined by the complexity of the sample. For mixtures, the programmed heating method is generally used. The setting of column temperature should take into account both high and low boiling or melting point compounds It can be modified according to different compounds, with the aim of separating the components of each compound in the shortest possible time.

　　

3 Precautions for gas chromatograph manufacturers:

　　

During the operation, it is necessary to first supply the carrier gas and then heat it up to prevent damage to the detector.

　　

3.2 When using a micro injector for sampling, be careful not to pull out the needle core of the injector to prevent damage to the injector.

　　

3.3 The detector temperature cannot be lower than the injection port temperature, otherwise it will contaminate the detector. The injection port temperature should be higher than the highest value of the column temperature, and the compound should not decompose at this temperature

　　

3.4 Compounds containing acids, bases, salts, water, and metal ions cannot be analyzed and must be treated before proceeding.

　　

3.5 The sample taken by the sampler should avoid bubbles to ensure reproducibility of the injection.

　　

3.6 Wash the needle repeatedly with solvent before sampling, and then wash the sample to be analyzed at least 2-5 times