Modeling approaches for temperature-programmed gas chromatographic retention times under vacuum outlet conditions

This contribution evaluates the performance of two predictive approaches in calculating temperature-programmed gas chromatographic retention times under vacuum outlet conditions. In the first approach, the predictions are performed according to a thermodynamic-based model, while in the second approach the predictions are conducted by using the temperature-programmed retention time equation. These modeling approaches were evaluated on 47 test compounds belonging to different chemical classes, un-der different experimental conditions, namely, two modes of gas flow regulation (i.e., constant inlet pres -sure and constant flow rate), and different temperature programs (i.e., 7 degrees C/min, 5 degrees C/min, and 3 degrees C/min). Both modeling approaches gave satisfactory results and were able to accurately predict the elution pro-files of the studied test compounds. The thermodynamic-based model provided more satisfying results under constant flow rate mode, with average modeling errors of 0.43%, 0.33%, and 0.15% across all the studied temperature programs. Nevertheless, under constant inlet pressure mode, lower modeling errors were achieved when using the temperature-programmed retention time equation, with average modeling errors of 0.18%, 0.18%, and 0.31% across the used temperature programs. (c) 2021 Elsevier B.V. All rights reserved.