Achieving a Peak Capacity of 1800 Using an 8 m Long Pillar Array Column.

In the present study, the peak capacity potential of ultralong porous cylindrical pillar array columns is investigated. Coupling 4 columns of 2 m long allows for working near the minimal separation impedance of small molecules under retained conditions at a maximal pressure load of 250 bar. Minimal plate heights of = 5.0 μm, = 6.3 μm, and = 7.7 μm were obtained for uracil (unretained), butyrophenone ( = 0.85), and valerophenone ( = 1.94), respectively, corresponding to a number of theoretical plates of = 1.6 × 10, = 1.2 × 10, and = 1.0 × 10. The optimal linear velocities were 0.60 mm/s for a retained compound and 0.74 mm/s for an unretained compound. Based on a mixture of 9 compounds, the peak capacity was determined as a function of gradient time (). Peak capacities (-based) of 1103 and 1815 were obtained when applying 650 min and 2050 min gradients ( = 4.5 and 14, respectively, with as the gradient time and as the void time). These values are much higher than earlier reported peak capacity values for small molecules.