title: Pi-selective stationary phases: (I) Influence of the spacer chain length of phenyl type phases on the aromatic and methylene selectivity of aromatic compounds in reversed phase high performance liquid chromatography.
abstract: Phenyl type stationary phases of increasing spacer chain length (phenyl, methyl phenyl, ethyl phenyl, propyl phenyl and butyl phenyl, with 0-4 carbon atoms in the spacer chain, respectively) were synthesised and packed in house to determine the impact that the spacer chain length has on the retention process. Two trends in the aromatic selectivity, q(aromatic), were observed, depending on whether the number of carbon atoms in the spacer chain is even or odd. Linear log k' vs phi plots were obtained for each stationary phase and the S coefficient was determined from the gradient of these plots. For the phenyl type phases, the S vs n(c) plots of the retention factors of linear polycyclic aromatic hydrocarbons vs the number of rings exhibit a distinct discontinuity that between 3 and 4 rings, which increases with increasing spacer chain length for even phases but decreases for odd phases. Accordingly, we suggest that the retention factors depend differently on the number of carbon atoms in the spacer chain depending on whether this number is even or odd and that this effect is caused by different orientations of the aromatic ring relative to the silica surface.
authors.affiliation: Australian Centre for Research on Separation Science, School of Natural Sciences, University of Western Sydney Node, Parramatta, NSW, Australia.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Stevenson
authors.forename: Kirsty J
authors.initials: KJ
authors.lastname: Mayfield
authors.forename: Arianne
authors.initials: A
authors.lastname: Soliven
authors.forename: Gary R
authors.initials: GR
authors.lastname: Dennis
authors.forename: Fabrice
authors.initials: F
authors.lastname: Gritti
authors.forename: Georges
authors.initials: G
authors.lastname: Guiochon
authors.forename: R Andrew
authors.initials: RA
authors.lastname: Shalliker
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D008968:Molecular Conformation; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry
chemical_list: D001555:Benzene Derivatives; D006841:Hydrocarbons, Aromatic; D011084:Polycyclic Aromatic Hydrocarbons