In gas chromatography (GC), a sample is introduced
into a heated injection port where the sample vaporizes to produce
gaseous constituents. These constituents are then carried into
the capillary column (stationary phase) with a continuous flow
of He or H2 gas (mobile phase).
Each constituent establishes a unique equilibrium with the stationary
phase, and is eluted through the column based on its affinity.
Volatile substances move through the column and are separated
in a relatively short retention time, whereas compounds with
low volatility require elevated temperature and longer retention
time. In general, using GC to analyze volatile organic compounds
is superior to other methods with regard to precision and accuracy.
The analysis time is usually short, and all steps can be easily