Chemistry
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Gas Chromatography

Gas Chromatography

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Gas chromatography is another type of chromatography. You might have heard of other techniques like thin-layer chromatography and column chromatography. Gas chromatography is used to separate samples in the gas phase. In this article, we'll explain what gas chromatography is, how it works, and its benefits. We'll also talk about how gas chromatography and mass spectrometry can be used together.

So, what is gas chromatography? It's a method of separating and analyzing compounds that are in a gas state. This works by passing the gas through a column that contains a stationary phase. The stationary phase separates the different components of the gas mixture, which can then be analyzed.

One of the benefits of gas chromatography is that it's very sensitive. This means it can detect very small quantities of compounds in a sample. Another advantage is that it's very precise, which is important when analyzing complex mixtures.

Gas chromatography can also be combined with mass spectrometry. Mass spectrometry is a technique that can be used to identify the individual components of a mixture. By combining gas chromatography with mass spectrometry, scientists can get even more detailed information about a sample.

In conclusion, gas chromatography is a useful technique for separating and analyzing compounds in the gas phase. Its sensitivity and precision make it a valuable tool in scientific research. When combined with mass spectrometry, it can provide even more detailed information about a sample.

What is gas chromatography?

Gas chromatography (GC) is a sensitive technique and is used for compounds that vaporise (turn from liquid to vapor) on heating without decomposing.

Gas chromatography, GC, is an analytical technique that analyses components of a sample in the gas phase.

Gas chromatography is also known as Gas-Liquid Partition Chromatography (GLPC).

This type of chromatography not only separates the chemicals in a sample but also gives a measure of how much of each is present. Therefore, it is useful in allowing chemists to analyse complex mixtures, both qualitatively and quantitatively.

How does gas chromatography work?

In gas chromatography, a column is packed with a solid or a solid coated with a viscous liquid. This is the stationary phase. The analyte solution is then vaporised and injected into the column. An unreactive gas such as helium acts as the mobile phase. It is passed through the column under pressure at a high temperature.

Vaporisation: the phenomenon of a liquid turning into vapour. Analyte solution: the solution that we want to analyse. Mobile phase: the fluid (liquid or gas) that flows through a chromatography system. It can also be called carrier gas.

The diagram is a visual representation of how gas chromatography works
The diagram is a visual representation of how gas chromatography works

To summarize the process of gas chromatography:

  1. The sample is injected into the carrier gas steam and passes through a coiled column coated with a viscous liquid.
  2. The chemicals in the sample turn into gases and mix with the carrier gas, passing through the column.
  3. The components in the mixture separate as they pass through the column and pass into a detector which sends a signal to a recorder as each component appears.
  4. A chromatogram is produced through a series of peaks, one for each component in the mixture.
  5. The chromatogram is then analyzed by chemists.

The sample injector is also known as the GC inlet, and some instruments use capillary columns made of materials such as stainless steel, borosilicate glass, or fused silica. Other columns are made of glass or steel tubes packed with powder coated with a thin film of a liquid with a high boiling temperature. These columns are generally used in gas

Gas Chromatography: Retention time

Retention time is an important factor in gas chromatography (GC) as it is used to identify the components of a sample. It is the amount of time it takes for a compound in a mixture to pass through the chromatography column and reach the detector. The separation of the components depends on the balance between solubility in the mobile phase and retention in the stationary phase. Each component in the sample absorbs into the stationary phase by a different amount, which means that each component takes a different amount of time from when it is injected to when it is recorded on the other end. A specific property, such as the thermal conductivity of gases leaving the column (in the case of the thermal conductivity detector, TCD) is measured by a detector on the other end of the column. A recorder then gives a peak on a plot showing the retention time. The area under each peak on the plot represents the relative quantities of each component.

Gas chromatography (GC) and mass spectrometry (MS)

If we combine gas chromatography with mass spectrometry, we produce a very powerful system that allows us to identify, separate, and measure complex mixtures of chemicals.

Gas chromatography is good at separating mixtures into their components. However, it is of no use when it comes to identifying these components. On the other hand, mass spectrometry is a technique used to identify substances according to their mass/charge ratio. Unknown compounds can easily be identified thanks to mass spectrometry. Therefore, the advantages of GC and MS are combined within GC-MS in order to make a very useful analysis tool.

The key features of a GC-MS system are as follows:

The sample is injected. The chemicals in the mixture separate at the GC column and exit it one by one. The separated components are sent into a mass spectrometer instead of a detector. A detailed mass spectrum is produced by the spectrometer for each component and this can be used to identify the components, as well as showing what the original sample consisted of.

Gas chromatography has several advantages that make it a popular analytical technique. Firstly, it has a high level of sensitivity, which means that it can detect a wide range of compounds. Secondly, it has a high resolution, which allows for different types of compounds to be separated. Thirdly, gas chromatography is an easy technique that gives accurate data and results. Fourthly, there are different types of injectors and detectors that can be used in many different applications. Finally, there are several types of detectors, including the flame ionisation detector (FID), electron capture detector (ECD), photoionisation detector (PID), and flame photometric detector (FPD), which can be used with gas chromatography.

In summary, gas chromatography (GC) is an analytical technique that analyses components of a sample in the gas phase. It has several advantages, including high sensitivity and resolution, ease of use, and versatility. Combining gas chromatography and mass spectrometry gives us a very powerful system that allows us to identify, separate, and measure complex mixtures of chemicals.

Gas Chromatography

What is gas chromatography?

Gas chromatography is an analytical technique that analyses components of a sample in the gas phase.

How does gas chromatography work?

In gas chromatography, a column is packed with a solid or a solid coated with a viscous liquid. This is the stationary phase. The analyte solution is then vaporised and injected into the column. An unreactive gas such as helium acts as the mobile phase. It is passed through the column under pressure at a high temperature. The components in the mixture separate as they pass through the column. They then pass into a detector which produces a chromatogram.

What is the basic principle of gas chromatography?

The basic principle of gas chromatography is that each component in the sample absorbs into the stationary phase by a different amount. This leads to different retention times for different components. The separation of the components depends on the balance between solubility in the mobile phase and retention in the stationary phase. 

How does temperature affect gas chromatography?

Temperature affects gas chromatography since it affects the retention time of the analyses, the pressure of the column, as well as the shape of the peaks which appear on the chromatogram.

What is the purpose of gas chromatography?

Gas chromatography separates components in a gaseous sample and gives us the quantities of each analyte present. Therefore, it is useful since it allows chemists to analyse complex mixtures, both qualitatively and quantitatively.

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