Does High Polarity Mean High Retention on Stationary Phases in Gas Chromatography?

Abstract

Stationary phase chemistry, polarity, and selectivity have been of ongoing interest since the inception of gas chromatography (GC) in the 1950s. In the early days when most analyses were performed on packed columns, there were hundreds of stationary phase materials available. Today, with modern capillary columns, most GC analyses are performed with a few stationary phases, with a wide array of choices for specialty applications. Stationary phases are often classified using the broad term polarity, with polar stationary phases recommended for separating polar analytes and nonpolar stationary phases recommended for nonpolar analytes. In this installment, we examine the idea of stationary phase polarity. We examine the assumptions inherent in the most popular stationary phase polarity evaluating systems—McReynolds constants and the polarity scale. We see that high polarity does not always mean greater retention or higher selectivity.