MOLECULAR SHAPE-RECOGNITION OF POLYCYCLIC AROMATIC-HYDROCARBONS WITH VARIOUS ALKYL DIPHENYL BONDED PHASES IN MICROCOLUMN LIQUID-CHROMATOGRAPHY

The basic retention behaviors of polycyclic aromatic hydrocarbons (PAH s) with various novel alkyl diphenyl bonded phases have been examined using microcolumn liquid chromatography The retention behaviors of PAH s with these phases have been compared to those with n-alkyl bonded ph ases which have the same carbon numbers but methyl side groups instead of phenyl groups. Three different alkyl chain lengths for both n-alky l dimethyl and n-alkyl diphenyl bonded phases such as C4, C8 and C18 w ere used in this study. It was found that these n-alkyl diphenyl phase s have a non-planarity recognition capability for small and medium PAH s, It appears that this capability increases as the alkyl chain length of the bonded phases decreases. The short or medium alkyl chain lengt h diphenyl bonded phases retained non-planar solutes better than the p lanar solutes. This trend is completely opposite to that with dimethyl analogs. This unique retention behavior is believed to be caused by s trong molecular-molecular interaction between non-planar solutes and t he two phenyl groups in those diphenyl stationary phases.