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Gas chromatography (GC) is a type of chromatography technique that is applied in analytical chemistry to separate and analyze various compounds that have the ability to vaporize without decomposing. One main application of gas chromatography is in the testing of purity of a given compound or in the separation of different components in a given compound. Its functions are not only limited to these two functions, but the technique has also proved to be very effective in the identification of specific compounds under investigation.
Gas chromatography equipment operates through the use of mobile and stationary phases. The mobile phase is made up of a carrier gas which in most cases is an inert gas such as helium or nitrogen which is not reactive. The stationary phase on the other hand is comprised of a microscopic layer of a liquid or polymer which is derived from an inert solid support which is located inside a piece of glass or a metal column. During the process of analyzing a compound, the gaseous state of the compound under investigation is allowed to come into contact with the walls of the column which is coated using a number of different stationary phases. This interaction in turn causes the compounds present to get extracted at different times during the process of separation. The time at which a certain compound is eluted is referred to as the retention time of that compound. After the separation process is through, the person carrying out the experiment is able to compare the different retention times that are obtained which makes gas chromatographs very useful analytical instrument.
Gas chromatography has some notable differences which makes it unique from column chromatography. The most significant difference is the use of liquid stationary phase and a gas mobile to separate the compounds where as column chromatography uses a solid stationary phase and a liquid mobile phase.
Carrier gas which must be an inert gas for it to function effectively and examples include nitrogen, helium, argon and carbon dioxide.
The type of detector that is been used influences the type of carrier gas to be used.
Sample injection port provides an opening where the sample can be introduced into the system for analysis. It is recommended that the sample being analyzed be of the right size as large compounds can lead to broadening of the injection port. The compound been introduced into the system should be in vapor form.
Columns are the other key components of the instrument and they occur in two types which are the packed and capillary forms. Packed columns are comprised of finely divided, inert, solid support material which is coated with a liquid stationary phase while the other types of columns are made up of capillaries which have walls coated with liquid stationary phase.Column temperature within which the instrument operates is the other vital component. The recommended temperature should be slightly above the boiling point of the sample under investigation.
Several detectors are used in gas chromatography but the most common ones are flame ionization detector and thermal conductivity detector which are sensitive to wide range of components and can work over a wide range of concentrations.
The use of gas chromatography technique is highly applicable in many fields of science where it is used to study and analyze different compounds. Areas of study include forensic science, microbiology, analytical chemistry, biochemistry, biomedical sciences, medicine, molecular biology, pharmacy and many other science related fields.
A number of companies have been ranked as top manufactures of gas chromatographs.
Gas chromatographs are readily available from different specialist suppliers which deal with the sale of the genuine products which are obtained from registered manufactures. Oxford Labs is a leading marketplace in Europe for the sale of new and used laboratory equipment including GC systems.