Читать книгу Process Gas Chromatographs - Tony Waters - Страница 42

Inside the column, sample molecules that are traveling in the carrier gas touch the stationary phase. What happens next depends on what kind of stationary phase is present, a solid or a liquid.

Most PGC columns employ a liquid stationary phase, which works by selectively dissolving the component molecules. Since they are so common, it is reasonable to use liquid‐phase columns as our example for explaining how the chromatographic process works. Therefore, the rest of this chapter will discuss only gas‐liquid interaction.

Columns employing a solid stationary phase are used to separate simple gases like hydrogen, oxygen, nitrogen, or methane. Gas‐solid columns work by selectively adsorbing the sample molecules. This is a different mechanism, but it has the same effect; the column retains one kind of molecule longer than it retains another kind of molecule.