Identification evaluation of retention mechanisms in gas-liquid chromatographic systems

Abstract

A procedure for identification of the retention mechanisms in gas-liquid chromatographic systems is proposed. It is based on the introduction of a sorption model for these systems, in which the presence of two layers of liquid stationary phase on the support is assumed. First a multimolecular layer of highly oriented molecules adjacent to the solid surface is formed, followed by a second bulk layer. The partition properties of both layers were expected to be different due to their structural peculiarities. An appropriate retention equation assuming all probable sorption retention mechanisms is derived. Problems attendant upon the application of this equation for identification purposes are discussed. The knowledge of some experimental parameters and the employment of a suitable computer program lead to unequivocal identification of solute retention mechanisms as well as to determination of partial partition coefficients. The reliability of the identification procedure was verified with published and new experimental data. Calculated partition coefficients allowed to the evaluation of the relative contributions of the identified mechanisms to the solute retention. The results obtained are in good agreement with the requirements of the introduced sorption model.