A component of a gas chromatography analyser that functions as a narrow flow-through tube through which different chemical constituents of a sample pass in a gas stream at different rates, depending on their various chemical and physical properties and their interaction with a specific column filling. The tubing is typically: 1) Packed: usually stainless steel or glass and containing a packing of finely divided, inert, solid support material (e.g., diatomaceous earth) that is coated with a liquid or solid; or 2) Capillary: usually fused silica with synthetic polymer coating and with very small internal diameter (few tenths of a mm) coated with active materials and sometimes micropores.