Chromatography Column: Van Deemter Plate Theory

Two analytes are injected together at the top of a packed chromatography column and swept downward by a mobile-phase flow. Each molecule repeatedly partitions between the moving fluid and the stationary phase coating the packing, according to its own partition coefficient — the more it favours the stationary phase, the further it falls behind. As the bands travel they also broaden, following the Van Deemter equation for plate height, so the flow velocity that separates two analytes fastest is not necessarily the flow velocity that separates them best. Tune flow velocity, column length, particle size and the second analyte's polarity, and watch the resolution between the two elution peaks respond in the live chromatogram below the column.