out using other solutionsAs the name suggests, gas chromatography is simply the same technique of mobile and
stationary phases performed with a gaseous eluent (instead of liquid). The stationary phase is
usually a crushed metal or polymer.
Historically, HPLC was performed at high pressures, whereas column chromatography uses
gravity to pull the solution through the column. Now, HPLC is performed with sophisticated and
variable solvent and temperature gradients, allowing for much more specific separation of
compounds than column chromatography; high pressures are no longer required.