Separation of polycyclic aromatic hydrocarbons with various C₆₀ fullerene bonded silica phases in microcolumn liquid chromatography

Various chemically bonded C₆₀ fullerene silica phases were synthesized as stationary phases for liquid chromatography (LC) and their retention behaviors were evaluated systematically with various polycyclic aromatic hydrocarbons (PAHs) using microcolumn LC. The results clearly indicate that the C₆₀ bonded phases have a unique molecular recognition capability. With the C₆₀ bonded phases, planar PAHs having a partial structure similar to that of the C₆₀ molecule were retained longer than analogous PAHs molecules without the partial structure of C₆₀. The results also show that the C₆₀ bonded phases with higher surface coverage (C-high type), i.e., 0.411 and 0.351 μmol m^-2, offered a selectivity different from that of the C₆₀ fullerene bonded phases with lower surface coverage (C-low type), i.e., 0.102 and 0.159 μmol m^-2 for the separation of isomeric PAHs. These retention behaviors can be explained by the fit of the molecular shape of the solute molecules to the stationary phase ligands. The separation of C₆₀ and C₇₀ fullerenes was also examined with various C₆₀ bonded phases and the results showed that the separation factors were comparable to those with commercially available octadecylsilica (ODS) phases.