Kinetic performance of narrow-bore columns on a micro-system for high performance liquid chromatography

The kinetic performance of 0.5 mm × 50 mm columns packed with 2.7 μm Halo-C18 core–shell particles and 3 μm EP-120-C18 fully porous particles fitted on an Eksigent LC-Express Ultra μHPLC system were measured. The instrument contribution to band broadening was obtained by directly connecting the injection valve and the detector cell with a short, narrow PEEKSIL tube. The connections between the column and the connecting tubes, the column endfittings and its frits contribute to band spreading and are responsible for a significant rear peak tailing, even for retained compounds, resulting in a significant loss of efficiency. Our results show that the μHPLC system could outperform the current VHPLC systems using 2.1 mm I.D. columns packed with 1.7 μm particles if it were using 0.5 mm I.D. columns packed with 1 μm particles, if it could operate at a few kbar pressure drop, and if the sum of the contributions of the instrument, column endfittings and the column frits to band dispersion were three times smaller than it is at present.