What are the gases needed for gas chromatography?

First, the pure gas, the inert gas:

Gas chromatography (GC) usually uses a pure gas as the mobile phase.

Gas chromatography is a technique that achieves separation based on the difference in partition coefficients of different components in stationary and mobile phases. Gas chromatography has been widely used in the field of chemical analysis because of its advantages of high sensitivity, high selectivity, high efficiency, fast speed, wide application range, and small sample size.

The choice of which gas to use as the mobile phase usually depends on the specific conditions of the desired analysis, the budget, as well as the safety requirements of the experiment.

Common ones are as follows:

1. Nitrogen (N2): is one of the most commonly used mobile phase gases for gas chromatography, as it is an inert gas that does not react chemically with samples, and is inexpensive and easy to obtain.

2. Helium (He): Due to its small molecular weight and fast diffusion speed, it is often used for rapid analysis, but the cost is relatively high.

3. Argon (Ar): It may be used in some special analyses, but is less commonly used than nitrogen and helium due to its cost and performance considerations.

4. Hydrogen (H2): Although hydrogen has a very fast diffusion rate, which can improve the efficiency of analysis, special attention should be paid to safety when using it due to its flammability.

The second is mixed gas:

1. Improve separation efficiency: In some complex analyses, a mixture of two or more inert gases may be used as the mobile phase in order to achieve better separation results.

2. Special test requirements: When determining the concentration of specific compounds, such as methane, nitrous oxide and carbon dioxide in gases, specific gas mixtures may be used according to the test requirements and standards.

3. Improve peak shape: In the analysis process, in order to improve the shape and resolution of the chromatographic peak, sometimes mixed gas is used as the mobile phase.

Again, the standard gas:

Standard gases commonly used in gas chromatography mainly include CH4(methane), N2O(nitrous oxide) and CO2(carbon dioxide).

In gas chromatography, the role of standard gases is very important. They are used to calibrate instruments and ensure the accuracy and reliability of analytical results. The details are as follows:

1. Methane (CH4): As a common gas standard, methane is commonly used in environmental monitoring, natural gas analysis and other fields.

2. Nitrous oxide (N2O): This gas is often used as a standard gas in agriculture, environmental protection and other fields of analysis.

3. Carbon dioxide (CO2): Because its concentration in the atmosphere has an important impact on the environment, carbon dioxide is often used as a standard gas for environmental monitoring.

What should we pay attention to the gas used in gas chromatography?

When using mixed gas, it is necessary to ensure that the proportion and purity of the gas meet the experimental requirements to ensure the accuracy of the analysis results.

At the same time, the operator should be familiar with the use and maintenance of the gas chromatograph to ensure the smooth progress of the experiment.

When using these standard gases, attention needs to be paid to the purity and proportion of the gases to ensure that they can meet the requirements of the analysis.

In addition, certain precautions, such as the use of a gas filter or purification device, may be necessary to prevent dust from the gas sample from entering the gas path of the instrument.