Linear programming of inlet pressure or flow-rate in isothermal gas chromatography with near-vacuum outlet pressure

The equation of motion for a peak in a gas chromatography experiment is shown to be exact whenever the column outlet pressure is approximately zero. Based on steady-state assumptions, this equation is solved for an isothermal analysis with a single-ramp inlet-pressure or flow-rate program. Theoretical calculations of retention times are confirmed experimentally for two n-alkanes using a capillary column connected to a mass-selective detector. A slight but consistent discrepancy between theoretical and measured results is interpreted as a failure of the steady-state assumption when the magnitude of the rate of change of inlet pressure is large.