Molecular shape recognition of polycyclic aromatic hydrocarbons with various alkyl diphenyl bonded phases in microcolumn liquid chromatography

Abstract

The basic retention behaviors of polycyclic aromatic hydrocarbons (PAHs) with various novel alkyl diphenyl bonded phases have been examined using microcolumn liquid chromatography The retention behaviors of PAHs with these phases have been compared to those with n-alkyl bonded phases which have the same carbon numbers but methyl side groups instead of phenyl groups. Three different alkyl chain lengths for bothn-alkyl dimenthyl andn-alkyl diphenyl bonded phases such as C4, C8 and C 18 were used in this study. It was found that thesen-alkyl diphenyl phases have a non-planarity recognition capability for small and medium PAHs. It appears that this capability increases as the alkyl chain length of the bonded phases decreases. The short or medium alkyl chain length diphenyl bonded phases retained non-planar solutes better than the planar solutes. This trend is completely opposite to that with dimethyl analogs. This unique retention behavior is believed to be caused by strong molecular-molecular interaction between non-planar solutes and the two phenyl groups in those diphenyl stationary phases.