Molecular Shape Selectivity for Polycyclic Aromatic Compounds on a Core–Shell Octadecylsilica Stationary Phase at Subambient Column Temperatures

Molecular shape selectivity for polycyclic aromatic compounds on a core–shell-type octadecylsilica (ODS) phase at subambient column temperatures was studied in reversed-phase liquid chromatography. The plate height on the core–shell ODS column was relatively stable at subambient column temperatures when compared with that of a conventional ODS column. In order to compare the sample diffusivities in the conventional and core–shell ODS columns, van Deemter plots were prepared. The plate height of the core–shell column was significantly lower than that of conventional column, suggesting an advantageous feature of the core–shell-type stationary phase especially at a high flowrate of the mobile phase. An enhanced molecular shape recognition capability of the core–shell ODS phase was also confirmed at subambient column temperature. The result could be consistent with an improved shape selectivity as normally observed on conventional ODS phases at low temperatures, however, the enhanced molecular shape recognition capability of the core–shell phase enables a good separation between benz[a]anthracene and chrysene at subambient column temperatures. Similar improved shape selectivities for terphenyl isomers were also confirmed on the core–shell phase.