Gas Chromatographic Techniques to Elucidate the Working Mechanism of Graphitized Carbon Black-Liquid Modifier-Eluate Interactions

The modification in adsorption properties caused by very small amounts of organic compounds when preadsorbed on the surface of graphitized carbon blacks are discussed in terms of the heats of adsorption of different compounds on the modified surface. The results obtained by deposition of large molecular weight molecules, such as those used as stationary phases in gas chromatography, are compared with those obtained when the preadsorbed molecules belong to the same compound. The heats of adsorption are measured at different surface coverages. As a consequence of the surface modifications, the graphite surface becomes highly homogeneous. This, in turn, leads to better performance of the graphitized carbon blacks as stationary phases for gas chromatography. The main advantage is that with this technique selective stationary phases can be obtained making fast analysis possible in terms of linear gas velocity while maintaining very low HETP when compared to gas-liquid systems.