Stationary phase support:

The reasons of the solid phase are to support a thin uniform film of liquid phase. An optimum support should have certain features:

• A huge specific surface area - from 1 to 20 sq. metres per gram
• A pore structure along with uniform pore diameter in the range of l0 µ or less
• Inertness - a minimum of adsorptive and chemical interaction with the solutes
• Regularly shaped particles and uniform within size for efficient packing.
• Mechanical strength - it should not crush on handling.

No material has yet been elaborates that fulfills all these requirements; therefore, various suitable supports are commercially available. Commonly one must select among inertness and efficiency (high surface area). The raw material for most gas chromatographic support is diatomite also known as diatomaceous silica, diatomaceous earth, and kieselguhr. Diatomite is composed of skeletons of diatoms, microscopic unicellular algae that are primarily micro- amorphous hydrous silica, while a few micro impurities majorly metallic oxides are present.