Investigation of surface-molecule interactions on the silica gel surface by the gas phase titration method

The distribution of adsorption sites on the silica gel surface was investigated by applying the chromatographic gas phase titration method. Ethylmethylketone was the blocking agent, and n-octane, benzene, and chloroform were the testing agents. These substances were chosen because of their various types of intermolecular interactions, i.e., nonspecific, electron-donor, and electron-acceptor, respectively. The retention data for all testing agents were directly compared, apart from the differences in volatility of these adsorbates. Three kinds of adsorption sites, differing in their interaction energy, were found on the silica gel surface for each testing agent. The results obtained were discussed in terms of various types of surface-molecule interactions. Then, the changes in free enthalpy of adsorption were calculated for all testing agents. Based on these data, the influence of ethylmethylketone on the interactions of the silica gel surface was estimated. (C) 1997 Academic Press.