title: Behaviour of the isothermal retention indices of n-alkylbenzenes on stationary phases of different polarity.
abstract: Isothermal retention indices (I) of benzene, toluene, ethylbenzene, n-propylbenzene and n-butylbenzene were determined at 323-423 K on twelve WCOT capillary columns covering a broad stationary phase polarity spectrum. These I values have been tested carrying out a comparison with the NIST database values. The effect of the stationary phase polarity on I values was studied. But for the poly(3,3,3-trifluoropropylmethyl siloxane) column, a good linear correlation was found. At each temperature, the dependence on I of the alkyl chain length (z) attached to the ring of the n-alkylbenzenes was linear and of similar magnitude for the stationary phases of low to middle polarity, but lower for the more polar ones. Moreover, an important influence of the column temperature on the slope of the I vs. z plots was observed for the only non polysiloxane-type stationary phase studied, i.e., poly(ethylene glycol), due to its higher chain stiffness. Finally, different expressions describing the effect of the temperature on the retention index have been compared. I values of the n-alkylbenzenes in the 323-423 K range increase with increasing column temperature according to the Antoine-type (I=α+β(γ+T)(-1)) and the extended (I=a+bT(-1)+clnT) models. No significant differences were observed between them, except for the poly[70% bis(3-cyanopropyl) 30% dimethyl silphenylene-siloxane] column, for which the Antoine-type model was slightly better.
authors.affiliation: Instituto de Química-Física Rocasolano (CSIC), Serrano 119, 28006 Madrid, Spain. santius@iqfr.csic.es
authors.forename: José María
authors.initials: JM
authors.lastname: Santiuste
authors.forename: Jesús Eduardo
authors.initials: JE
authors.lastname: Quintanilla-López
authors.forename: Jószef M
authors.initials: JM
authors.lastname: Takács
authors.forename: Rosa
authors.initials: R
authors.lastname: Lebrón-Aguilar
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry*; D002849:Chromatography, Gas / Q000295:instrumentation* / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D011092:Polyethylene Glycols / Q000737:chemistry; D012044:Regression Analysis; D012833:Siloxanes / Q000737:chemistry
chemical_list: D001555:Benzene Derivatives; D012833:Siloxanes; D011092:Polyethylene Glycols