How Chemistry Determines Separations: Influence of Selectivity on Resolution

Resolution in chromatography is influenced by retention, engineering, and selectivity. Retention relates to how long analytes are in the column; generally, longer retention leads to increased resolution. Engineering relates to the design and operation of the chromatographic system, as expressed by the number of theoretical plates. Generally, more theoretical plates lead to greater resolution. Finally, selectivity is generated by the chemistry of the intermolecular interactions between the stationary phase and the analytes. Larger differences in the strength of these interactions leads to greater selectivity. In this installment, we examine the relationship between selectivity and resolution.