Types of capillary columns in gas chromatography

Types of capillary columns in gas chromatography Gas Chromatography is a type of column chromatography that uses no mobile phase.

The stationary phase can be solid or liquid.

Similarly, it can be called as Gas solid chromatography or gas-liquid Chromatography respectively.

The gas-liquid chromatography can also be referred to as the Portable gas chromatograph technique since the gas-solid chromatography technique is more limited due to the semipermanent retention of compounds on the inners lining of the capillary column.

Here in this article, I will be discussing the types of columns used in gas chromatography. So consider the points on the pros and cons of using the columns in gas chromatography.

There are two types of columns used in gas chromatography: Capillary Columns and Packed Columns.

Capillary GC Columns These are the most popular capillary column used worldwide. It is installed in more than 80% of the applications. The reason behind their worldwide popularity is because they are fast and efficient. It is more affordable as compared to the packed columns.

It is also known as the open tubular columns because their tubes are open at both ends and add no resistance to the flow of the sample. The stationary phase is coated inside the inner wall of the capillary tubes.

The open tubular GC columns can be divided into three types as discussed below: Porous Layer Open Tubular Columns: These columns are containing an inner layer of porous adsorbent which can be molecular sieves or Alumina. It is widely used and commercialized for the detection of volatile compounds and light-fixed gases. It was developed in the late 1950s.

Wall Coated Open Tubular Columns: Here the tube wall is made up of Fused Silica. The inner wall is coated with the stationary phase with a thickness of 0.05-3 micrometers. It is 100 times better in efficiency as compared to the packed columns.

Support Coated Open Tubular Columns: The solid support adsorbed on the outer layer can be Celite. The inner lining is lined with the Liquid Phase which is thicker than the earlier columns i.e. WCOT. This indicates the higher capacity to hold the sample. However, the WCOT columns have been improved to include a thicker liquid phase due to cross-linking.

Fused Silica Open Tubular Column: Fused silica is better than glass as it is not fragile and less reactive with other chemical compounds. This in turn increases its efficiency. They have been used and appreciated for a long duration of time.

The walls are thinner and a polyamide coating is done on the outside which provides it the strength to bear the rush. They are highly flexible and a coating of stationary phase is done on the inner wall.

Packed Columns They are the first commercial columns developed for use in both GSC and GLC methods. In this, the stationary phase is directly coated onto the columns. The liquid phase is adsorbed on the inert solid coating or the beads of the capillary.

Usually, they are made up of stainless steel but can be prepared from alternative inert materials like steel with glass or Teflon coating, nickel, and many more. The length ranges from 0.61-3.05 m and the outer diameter can be 0.64 or 0.32 cm.

SOURCE https://www.articleted.com/article/423042/45135/Types-of-capillarycolumns-in-gas-chromatography