Intermolecular Interactions in Gas Chromatography on Carbon Black Coated with Monolayers of Hydrocarbons with Different Electronic Structures

Abstract

The adsorption and chromatographic properties of surfaces obtained by the adsorptive modification of thermally graphitized carbon black (TGCB) with hydrocarbons differing in composition and electronic structure (n-dotriacontane and coronene) were studied by gas chromatography (GC). The contributions towards the retention of methylene groups in homologous series of n-alkanes, alkylbenzenes, ethers, esters and n-alcohols were estimated for TGCB coated with monolayers of the above-mentioned hydrocarbons. The thermodynamic characteristics of the adsorption process were also measured for molecules of the various classes of organic compounds described. In addition, differences in the mechanism of chromatographic retention on n-alkane monolayers, when the latter may exist as solid-like, transitional or liquid-like states, and on coronene monolayers were studied. The influence of the electronic configuration of the carbon atoms in the modifier molecules on the adsorption energy of the various organic compounds studied has been demonstrated. The possibility of employing GC methods for demonstrating phase transitions in long-chain alkane monolayers adsorbed on carbon black is discussed. Furthermore, the possibility of controlling the retention selectivity during GC by TGCB modification with adsorbed monolayers of hydrocarbons is presented.