Potential advantage of constant pressure versus constant flow gradient chromatography for the analysis of small molecules

► Separations of complex mixtures by gradient elution run at constant flow rate and at constant pressure were modeled earlier. ► The maximum pressure reached in constant flow rate is the pressure in constant pressure mode. ► Experiments made at pressures of 250 bar and lower, with two columns confirm theoretical results. ► Analysis times are 20% shorter in constant pressure than in constant flow rate gradient mode. ► Peak capacities achieved at constant elution time of the most retained compound are nearly the same.