What Is A Capillary Column And Types Of Capillary Columns?

A capillary column for GC is fundamentally a very slender tube with the fixed phase veneering the internal surface. In packed columns the static phase is glazed onto the packing elements. A capillary column comprises of a couple of sections – the tubing and stationary phase.

Fused silica and stainless steel are the chief tubing ingredients. Moreover there are plenty of stationary phases- such as high molecular weight, thermally balanced polymers that are liquids or gels. But the most commonly seen stationary phase are polyethylene glycols, polysiloxanes and some tiny permeable elements constituted of polymers or zeolites.


In gas chromatography, mainly three types of capillary columns are used.

  1. Wall Coated Open Tubular (WCOT)
  2. Surface Coated Open Tubular (SCOT)
  3. Fused Silica Open Tubular ( FSOT)

Wall Coated Open Tubular (WCOT)

Here in the interior wall of the capillary column is layered and veneered with a very fine layer of fluid stationary phase.

Surface Coated Open Tubular (SCOT)

The capillary tube wall is layered with a skinny strata of solid balance on to which fluid phase is immersed. The separation efficiency of SCOT columns is higher than WCOT columns due to the enhanced surface domain of the stationary phase layer.

Fused Silica Open Tubular (FSOT)

Walls of capillary fused silica tubes are reinforced by a polyimide coating. These are malleable and can be twisted into coils.

Uses of Capillary Column in GC

Gas Chromatography is a universally used analytic procedure in many scientific research and industrial laboratories for quality analysis as well as recognition and quantitation of composites in a blend. GC is also a regularly used technique in many ecological and forensic labs because it permits for the exposure of very tiny volumes and quantities.

A wide variety of tasters can be investigated as long as the compounds are appropriately thermally balanced and rationally unstable. In all gas chromatography analysis, the separation of various compounds happens because of their collaboration with the stationary and mobile stages. Such as in simple chromatography a solvent (water and alcohol.) drifts over the paper (stationary) flowing the sample with it.

Principle of Operations

The diverse compounds which constitute the sample will drift more or less sluggishly depending, in simple terms, on how much they cling to the paper. The stickier amalgams move more unhurriedly therefore move a smaller distance in a stipulated time subsequent result being separation.

In gas chromatography the gas is the mobile stage, the column veneer is the stationary stage and the boiled element is alienated by how long the essential compounds take to appear from the other terminal of the column and flow into the detector. This is known as the retention time.

One can acquire columns layered with various stationary phases banking on what type of compounds one wishes to examine as the type of stationary section will regulate which compounds pass over it faster or slower.