Evaluation of PGC Stationary Phases Under High-Temperature LC Conditions for the Analysis of Parabens in Food Samples

Abstract

Porous graphitic carbon (PGC) columns for liquid chromatography (LC) represent an alternative to octadecyl‑bonded silica columns for the separation of both polar and nonpolar molecules. This is accomplished by exploiting the polarizability of the stationary phase interacting with the functional groups of the analytes. However, the elution of nonpolar compounds requires a high percentage of organic solvent, losing the intrinsic advantage of reversed‑phase aqueous separations. In this article, we aimed to exploit an additional advantage of such columns, viz. the resistance at high temperatures. Superheated water was employed as the mobile phase, taking advantage of the decrease in water dielectric constant by increasing the temperature. In this context, our goal was to minimize the percentage of organic solvent utilizing high temperatures (up to 250 °C) to achieve fast and “green” separations. The new developed high-temperature LC instrument was applied to the analysis of parabens in food samples.