Critical comparison of performances of superficially porous particles and sub-2 microm particles under optimized ultra-high pressure conditions.

The performance of 2.7 microm superficially porous particles at 600 bar and sub-2 microm fully porous particles at 1000 bar were compared by the Poppe plot method. Theoretical Poppe plots were first constructed for each stationary phase to compare their kinetic performance at different analysis times. The theory was then verified by experiments under the optimized conditions identified from the Poppe plot calculation. We found that the 2.7 microm superficially porous particles at 600 bar can provide similar performance compared to the sub-2 microm fully porous particles at ultra-high pressure (1000 bar) when analysis times are very short (e.g. sub-minute). As analysis time increases, the superficially porous particles start to outperform the sub-2 microm particles and can give much higher efficiencies (e.g. > 2 times higher plate count) at very long analysis times (>3h). The comparison was extended to gradient elution of a mixture of pharmaceutical interest by constructing gradient peak capacity Poppe plots and similar behavior was observed.