Kinetic plot equations for evaluating the real performance of the combined use of high temperature and ultra-high pressure in liquid chromatography: Application to commercial instruments and 2.1 and 1 mm I.D. columns

The use of ultra-high pressure liquid chromatography (UHPLC) with pressures up to 1000 bar and columns packed with sub-2-μm particles combined with high-temperature mobile phase conditions (up to 90 °C) is assessed according to the current available instrumentation via constrained kinetic plot equations. It is shown that the gain in separation speed, theoretically expected from high-temperature UHPLC (HT-UHPLC), is significantly reduced when taking into account the existing instrumental constraints (extra-column band broadening, flow-rate and column length limitations). This study also shows that significant improvements could be expected on the current commercial instruments by increasing the flow-rate limit and/or using packing columns with particle size in the range 2.5–3.5 μm instead of the current sub-2 μm. These particles should obviously withstand very high pressure.