The dependence of reduced plate height on reduced velocity in carbon dioxide supercritical fluid chromatography with packed columns

Summary

The relation$h = B/\nu + A + C \cdot \nu + D \cdot \nu ^2$ is proposed for the dependence of reduced plate height, h, on reduced velocity in carbon dioxide, supercritical fluid chromatography with packed columns. The classical Knox model does not take into account the density drop in the column which produces a peak-broadening. A supplementary coefficient with a parabolic dependence on velocity must be added and then a good fit between experimental results and theory is observed. Finally, the influence of other parameters such as pressure, capacity factor and solute molecular area is discussed.