Gas Chromatography: Types of Columns and Stationary Phases

In gas-liquid chromatography, nonpolar liquid stationary phases, such as dialkyl siloxanes, are used for less polar solutes, while polar liquids are chosen for polar solutes.

The stationary phase is usually stabilized on open tubular or capillary columns, which enable a high gas flow rate due to the open flow path.

In wall-coated open tubular columns, the liquid stationary phase is coated on the inside wall of the column.

In support-coated open tubular columns, the liquid stationary phase is coated on a layer of solid support that is bonded to the inner column wall.

Porous-layer open tubular columns with solid stationary phase particles coated onto the inner wall are used in gas-solid chromatography.

While capillary columns provide high resolution, high sensitivity, and short analysis times, they have low sample holding capacity.

For increased capacity, packed columns, which are usually coiled tubes filled with particulate solid support that holds the liquid phase, are preferred.

Although packed columns provide low resolution, decreasing the particle diameter can improve column efficiency.