Selectivity in a liquid chromatography (LC) separation is the ability to separate a molecule from other similarly structured compounds, such as conformational, positional, and optical isomers. Columns do this in a variety of ways that depend on the structural differences between the key target molecules. This is most commonly done by tailoring the column’s stationary phase so that the different target molecules interact either in different ways or in different strengths. The mobile-phase composition also can influence selectivity and retention mechanisms. For example, methanol and acetonitrile often have similar elution strengths in reversed-phase LC. But methanol can hydrogen bond but is a weak dipole, while acetonitrile cannot and id a strong dipole. Analogous differences for other possible solvent pairs are key to certain separations.

Areas Covered    

Course Level - Advanced

Who Should Attend   

Those who develop, maintain and operate LC methodologies

Why Should You Attend

LC separations are critical and difficult. Understand how separation works, ways to monitor performance, and symptoms of potential problems all help to maintain top-level performance. A separation is a competition between the analytes’ specific properties and those of the stationary and mobile phases. Changing either or both phases can increase or decrease separation and selectivity.There are numerous variables for each. A systematic examination of the difference between analyte structures can create possible good choices of stationary and mobile phases that result in acceptable chromatograms.