3.3.2 Actuator Gas

Pressurized gas is required to degas solvents and to drive many of the mechanical functions of modern HPLCs. Solvents used as the mobile phase contain trace concentrations (ppm) of atmospheric gases (N₂ and O₂) which create bubbles in the pump (during the low pressure intake of solvents) causing pumping problems. Dissolved gases can also evolve in the low pressure detectors in ultrahigh pressure LC, ion exchange, and supercritical fluid chromatography giving the appearance of a chromatographic peak depending on the specific detector being used. Pressurized gas is also needed to turn the six-port injection valve during automatic injection mode.

©Dunnivant & Ginsbach, 2008