Retention behavior of large polycyclic aromatic hydrocarbons on metalloprotoporphyrin-silica stationary phases

The retention behavior of large polycyclic aromatic hydrocarbons (LPAHs) (g reater than or equal to 7 rings) on newly developed metalloprotoporphyrin ( MProP)-silica stationary phases is examined and the results are compared to previously reported data for retention of the same solutes on commercially available phases. HPLC columns packed with FeProP-silica are shown to exhi bit unique shape selectivity for LPAH retention, with the planar LPAHs alwa ys retained much longer than corresponding non-planar solutes. Solute plana rity, length to breadth ratio (L/B value), and number of carbon atoms withi n the LPAHs are all demonstrated to contribute to the retention sequence ob served. Further, the retention of LPAH solutes on FeProP-silica phases is s hown to be more predictable than on other reversed-phase columns, with the elution sequence constant regardless of the mobile phase composition. Due t o the extremely high planar selectivity of FeProP-silicas with respect to L PAH retention, it is envisioned that columns packed with these phases could be used in conjunction with existing commercial columns to devise methods for more efficient separation of complex mixtures of LPAHs in environmental and other samples.