Question

In preparing a hexane acetone gradient on a normal phase HPLC column, is it desirable to increase or decrease the proportion of hexane as the column is eluted?

Answer 1

In the normal phase HPLC chromatography, the stationary phase is polar and it is an example of liquid-solid chromatography. So for preparation of a hexane-acetone gradient on normal phase HPLC column, the mobile phase should start less polar solvent (i.e. less acetone and more hexane) and increase the percentage of more polar solvent (i.e. increasing acetone and decreasing hexane) with time in order to force the late eluting solutes which are strongly adsorbed to the column surface.

In preparing a hexane acetone gradient on a normal phase HPLC column, it is desirable to decrease the proportion of hexane as the column is eluted.