Electronic Thesis and Dissertation Repository


Doctor of Philosophy


Chemical and Biochemical Engineering


Dr. Hugo de Lasa


This study focuses on a mathematical description of aromatic species elution peaks from a gas chromatographic BPX5 capillary column. Using the chromatographic peaks, statistical moments are calculated for toluene, naphthalene, phenol and 2-naphthol. This thesis reports two modelling approaches involving laminar gas flow, distribution coefficients (Ks) and diffusion coefficients in the stationary phase (Ds).

Firstly, a model with equilibrium adsorption is considered to describe symmetric peaks for toluene and naphthalene. Moreover, a model with non-equilibrium adsorption is proposed to describe asymmetric peaks of phenol and 2-napthol. In addition to the Ks and Ds parameters, this model involves adsorption kinetic constants (kads).

Validation of both mathematical models is developed by performing experiments at different carrier gas velocities and column temperatures (Tc). The model equilibrium adsorption, reports that the distribution coefficients, Ks, and the diffusion coefficients (Ds), solely depend on the solute and stationary phase properties. Furthermore, the model under non-equilibrium adsorption provides kads parameters for phenol and 2-naphthol. However, to fit the second moment, M2,exp, a revised model for the BPX5 column involving two classes of sites for solute adsorption is considered: one site with adsorption at equilibrium and the other site with adsorption at non-equilibrium.

Thus, this PhD thesis establishes two chromatographic models for aromatic hydrocarbon species peaks eluted from a BPX5 capillary column. Both mathematical models represent an important contribution to the knowledge of solute interactions in capillary columns for GC. These models may potentially have a significant impact on the future of GC analysis of complex mixtures.