Chromatographic Selectivity

Chromatographic resolution is a function of column efficiency (N), retention (k) and selectivity (α). It is usually written in the form of the resolution equation:

When resolution is plotted vs. these three parameters in Figure 1, it becomes apparent that selectivity has the greatest affect on resolution.

Affect of Selectivity on Improving Resolution

Figure 1. Affect of Selectivity on Improving Resolution

(Figure 1 courtesy of Mao, Y. Selectivity Optimization in Liquid Chromatography Using the Thermally Tuned Tandem Column (T3C) Concept. Ph.D. Thesis, The University of Minnesota, 2001.)

Watch our instructional web seminar on HPLC Column Fundamentals to get a detailed explanation of the efficiency, retention, and selectivity terms used in the Resolution Equation. 

Additional Topics:

Developing HPLC Methods on Ascentis

Functionalized Stationary Phases for Alternate Selectivity