GRAPHITIZED THERMAL CARBON-BLACK AS A SHAPE-SELECTIVE STATIONARY PHASE IN GC

The adsorption of molecules on the nonspecific and nonporous adsorbent graphitized thermal carbon black (GTCB) is mainly determined by their intermolecular dispersion interaction with the flat graphite surface. Since the retention values strongly depend on the geometrical configuration and shape of the investigated molecules and their arrangement on the graphite plane, it is possible to separate compounds with only small differences in their molecular shape on short columns packed with particles of pure or modified GTCB. The outstanding shape-selectivity of GTCB toward isomeric hydrocarbons is demonstrated by some examples. In most cases the elution sequences of isomeric compounds differ from that obtained in GLC using non-polar stationary liquids. Moreover, the well defined relationship between retention data and molecular structure by adsorption on a flat and homogeneous surface give useful information for the identification of separated compounds or for the investigation of the molecular structure.