Gas chromatography is a process to separate gas molecules of different size due to their different adsorption at macroporous surfaces, e.g. at activated charcoal. The separation is managed by the use of starting gas or heating up.

A molecule is a structure formed of atoms of various elements. It is the smallest concentration of same or different atoms that all chemical characteristics retain.

See also Free Radicals, Osmole, Enzyme Linked lmmuno Sorbent Assay, Gas Chromatography and Gel Chromatography.