Kinetic evaluation of new generation of column packed with 1.3 μm core–shell particles

The goal of this study was to critically evaluate a new generation of columns packed with 1.3 μm core–shell particles. The practical possibilities and limitations of this column technology were assessed and performance was compared with other reference columns packed with 1.7, 2.6 and 5 μm core–shell particles. The column efficiency achieved with 1.3 μm core–shell particles was indeed impressive, Hmin value of only 1.95 μm was achieved, this would correspond to an efficiency of more than 500,000 plates/m. The separation impedance of this column was particularly low, Emin = 2000, mostly due to a reduced plate height, h of 1.50. Comparing the kinetic performance of 1.3 μm core–shell particles to that of other particle dimensions tested in this study revealed that the 1.3 μm material could provide systematically the shortest analysis time in a range of below 30,000 theoretical plates (N < 30,000).Despite its excellent chromatographic performance, it was evident that this column suffers from the limitations of current instrumentation in terms of upper pressure limit and extra-column band broadening: (1) even at 1200 bar, it was not possible to reach an optimal linear velocity showing minimal plate height value, due to the low permeability of this column (Kv = 1.7 × 10−11 cm2), and (2) for these short narrow bore columns packed with 1.3 μm core shell particles, which is mandatory for performing fast-analysis and preventing the influence of frictional heat on column performance in UHPLC, it was observed that the extra-column band broadening could have a major impact on the apparent kinetic performance. In the present work, significant plate count loss was noticed for retention factors of less than 5, even with the best system on the market (σ2ec = 2 μL2)