What is chromatography? Chromatography is a technique used to separate the different components of a mixture by passing it through a medium in which various components move at different rates.
It is a very simple yet sophisticated technology that has its uses in multiple scenarios. It is mainly used for two different applications, for analytical purposes alone and purification and extraction of specific components from a given mixture.
Although it was initially used to separate the pigments in a plant leaf and other naturally occurring colorants, chromatography is a field that has inspired a lot of academicians. A Nobel prize in Chemistry was awarded in 1952 for making significant developments in the field of chromatography, including paper chromatography and gas chromatography.
It requires an adequate understanding of the concept of chromatography to understand what makes gas chromatography stand out from other chromatography techniques. Any chromatography techniques essentially have two components in it: the stationary phase and the mobile phase.
As the name suggests, the stationary phase is made to rest, and a solvent containing the mixture to be separated moves through the stationary phase. This solvent can be a liquid, or even a gas, as in gas chromatography.
The mixture to be separated or purified is fed into the chromatography chamber through the inlet. This inlet is connected to the analytical column, which is made up of fused silica or metal.
This analytical column would be coated with the fixed stationary phase on the inside, and the gaseous mixture passing through it is heated in the oven. The less volatile substances and the more volatile substances get separated at this same step.
These gases are passed through a detector where their characteristic spectrum is obtained and then sent to a computer. The acquisition software in the computer then analyzes the signals from the detector to form the chromatogram. This chromatogram, if studied, gives an exact idea regarding the components in it.
Factors affecting gas chromatography
Gas chromatography is a relatively new field of study whose applications are still being probed by various industries like the petrochemical industry. This technique can prove to be very beneficial in finding different components present in it.
Often, the presence of certain pollutants, even if they are present only in trace quantities, can be found. However, gas chromatography is a specialized technique that can only be used when certain conditions are met with. To know why these conditions need to be met, one needs to ask, ‘how does gas chromatography work?’.
Gas chromatography is mainly used to identify and separate components of highly volatile mixtures. This is because the gas used as the mobile phase should transport the components of the mixture alongside the stationary phase.
This transportation is often aided by the oven’s heat, but that would only work if the mixture is volatile. Furthermore, the molecular weight of the components of the mixture should be less.
This is because the higher the molecular weight, the higher the probability not to be transported. Thermal stability is of paramount importance while handling gas chromatography.
The components with lower thermal stability can get disintegrated in the chamber, causing the detector to identify the spectrum of the components originally not part of the mixture. Proper caution needs to be taken to ensure that all the necessary conditions have been met before relying on the gas chromatogram.
Gas chromatography systems need to be maintained regularly to keep them intact. The gas chromatography system’s inlet is where the materials are heated and then fed to the tube. Therefore this inlet needs to be cleaned regularly and is prone to leaks.
The column, which is coated with a stationary phase on the inside, provides a perfect space for the dirt to accumulate. Over time, it can also act as a catalytic converter, and therefore has the potential to disintegrate the mixtures chemically.
Uses of gas chromatography
Gas chromatography is one method that is found to have the potential to separate more than a thousand components from a given mixture. However, the theoretical backup needed to understand all the chromatogram peaks containing a very high number of components still needs to be developed.
While cutting-edge research is still happening in this regard, one can say that the ability to operate gas chromatography equipment is quintessential to building a promising career, whether one aspires for industrial applications or academic qualifications.
While solid and liquid solutes can be separated and studied using simpler and more common methods, gas chromatography is the one-stop solution for volatile, thermally stable gaseous mixtures with many real-world applications.