Gas Chromatograph Operation Procedures Tips

Gas chromatograph is the main tool for the completion of gas chromatographic analysis, and to embody the characteristics of the operating cylinder, to achieve the purpose of rapid and accurate analysis, the operator must have good operating skills.

1 heating

Because of the different manufacturers and quality of gas chromatograph, the method of setting the temperature is different. For setting the temperature with the microcomputer setting method or the dial selection method, it is generally to directly set the number or select a suitable given temperature value to increase the temperature. , And if you use the knob positioning method, there are tips:

11 over-temperature positioning method will be adjusted to lower than the operating temperature temperature control knob about 30 °C, to the gas chromatograph temperature, when the temperature is about the operating temperature, with the temperature indicator and heating indicator, and then gradually temperature control Adjust the knob to the table position.

1.2 Step-by-step incremental positioning method Turn the temperature control knob at an angle in the direction of temperature increase. The temperature rise begins. The indicator light is on. When the temperature is basically stable, turn the temperature control knob in the same direction and start to continue to heat up, so that the adjustment is continued until Constant temperature at working temperature.

2 adjust the pool balance

Adjusting the pool balance is actually the balance of the heat-transferring conductive bridge, so that it has a more suitable output, and the adjustment skill is actually the same for the gas chromatographs with pool balance, zero adjustment, and recording zero adjustment:

The first step, use the pool balance or zero adjustment knob to adjust the recorder pointer to the second position of the platform, self-attenuation to l6 times. Observe the movement of the pointer of the recorder. Step 3: Use the record zero-knob to move the recorder pointer back to the original fourth step, return the attenuation, and observe the pointer movement of the recorder. Step 5. Use the zero adjustment knob or the pool balance knob to set the recorder. Pointer back to the original 3 ignition

Hydrogen flame gas chromatograph requires ignition at start-up, and sometimes requires flameout due to various reasons. However, we often encounter ignition conditions. Here are two ignition techniques:

3.1 Increase the hydrogen flow rate method First increase the hydrogen flow rate in the country, point to fire, and then slowly back to work, this method is common.

3.2 Reducing the flow rate of makeup gas First, reduce the flow of makeup gas. After the ignition, re-adjust the working conditions. This method is applicable to the use of hydrogen carrier gas, using air as the auxiliary gas and tail gas.

4 gas ratio adjustment

Hydrogen flame gas chromatograph three gas flow ratio, the relevant information are recommended as: nitrogen: hydrogen: air: l: l: 10, but due to the rotor flow meter indicates the inaccuracy of the flow, in fact who will go to demand this ratio What I think is that the airbags are well-matched with the aim of having both a high detector sensitivity and a good separation effect, but also not easy to turn off. In accordance with the above principles, the ratio of gas should be adjusted according to the following:

(1) Adjustment of nitrogen flow rate After the column conditions are determined, the effect of the separation of the sample components is good or bad, and the flow rate of nitrogen is the decisive factor, when the nitrogen flow rate is adjusted. The separation of the components should be observed by injection until the nitrogen flow rate is as large as possible and the sample components are well separated.

(2) Adjustment of hydrogen and air flow rate The adjustment effect of hydrogen gas and air flow rate can be checked by the size of the base flow, and the flow of hydrogen gas is first adjusted to be approximately equal to the flow rate of nitrogen gas. Then adjust the air flow. When adjusting the air flow, observe the change of the base flow. As long as the base flow is increasing, it should be adjusted to the opposite side until the base flow no longer increases. Finally, the hydrogen flow is increased slightly.