37.2.1—And understand the terms

In gas chromatography the stationary phase is a high-boiling, non-polar liquid held on a solid support. The mobile phase is an unreactive carrier gas. Retention time is the time from injection to the detector signal.

Compounds repeatedly partition between the gas and stationary liquid. The instrument records when each compound emerges, not its Rf.

A compound with weak attraction to the stationary liquid spends more time in the carrier gas and reaches the detector sooner.

The carrier gas is not the sample and retention time is not a boiling point, although volatility can influence how long a compound remains in the column.