A brief discussion on the operating skills of gas chromatograph

　　Gas chromatograph is the main tool for completing gas chromatography analysis. In order to reflect the characteristics of simple operation and achieve the purpose of fast and accurate analysis, the operator must have good operating skills.

　　1. Heating

　　Due to the differences in the manufacturers and quality of gas chromatographs, the methods of setting temperature are also different. For setting temperature by computer setting method or dial selection method, it is generally to directly set the number or select the appropriate given temperature value to increase the temperature. If the knob positioning method is used, there is a skill involved.

　　1.1 Overtemperature positioning method

　　Adjust the temperature control knob to about 30°C below the operating temperature to heat up the gas chromatograph. When the temperature reaches about the operating temperature, adjust the temperature control knob to the appropriate position gradually in conjunction with the temperature indicator and heating indicator.

　　1.2 Step-by-step positioning method

　　Turn the temperature control knob in the direction of heating by an angle, the heating starts and the indicator light comes on; when the temperature is basically stable, turn the temperature control knob in the same direction again to continue heating; make progressive adjustments in this way until the constant temperature is at the working temperature.

　　2. Pool balance

　　Adjusting the cell balance is actually adjusting the balance of the thermal bridge to achieve a more appropriate output. Talking about adjustment techniques is actually for gas chromatographs with adjustment functions such as cell balance, zero adjustment and record zero adjustment.

　　The first step is to use the pool balance or zero knob to adjust the recorder pointer to the appropriate position;

　　The second step is to attenuate to about 16 times and observe the movement of the recorder pointer;

　　The third step is to use the record zero adjustment knob to adjust the recorder pointer back to its original position;

　　The fourth step is to return to attenuation and observe the movement of the recorder pointer;

　　Step 5. Use the zero adjustment or pool balance knob to return the recorder pointer to its original position.