Retention Behavior of Various Aromatic Compounds on Poly(butylene terephthalate) Stationary Phase in Liquid Chromatography

Poly(butylene terephthalate)-coated silica (PBT) have been introduced as a stationary phase in liquid chromatography (LC) and the retention behavior of polycyclic aromatic compounds (PACs) was evaluated in reversed-phase LC. The trend for the retention was compared with that obtained on two types of commercially-available octadecylsilica (ODS) phases and phenylbutylsilica (PBS) phase. A good liner relationship between molecular size of planar PACs and the corresponding logarithmic retention factor was confirmed on the PBT stationary phase, and the trend is quite similar to that obtained on a conventional polymeric ODS stationary phase. In addition, a good molecular shape recognition capability of the PBT stationary phase was confirmed for several solute pairs consisted of planar and non-planar PACs with a similar two-dimensional molecular size. The selectivities to some planar/non-planar solute pairs on the PBT stationary phase were significantly better than conventional ODS phases, even when compared with that of typical polymeric ODS stationary phases operated in a similar experimental condition. In the case of structural isomers of dichlorobenzene and dibromobenzene, the elution order on the PBT stationary phase was o-, m- and p-, however the corresponding elution order in typical ODS phases, and PBS phase was different, o-, p- and m-. The results can be explained on the basis of the molecular-molecular interaction between the stationary phase ligand and the analyte molecule, because the PBT stationary phase has a similar partial chemical structure to these p-isomers on the silica support.