title: Determination of the accessible volume and the interaction parameter in the adsorption mode of liquid chromatography.
abstract: The main physical parameters in liquid chromatography of oligomers-the accessible volume and the adsorption interaction parameter-are discussed. It is shown, that in liquid adsorption chromatography (LAC) there is a linear relation between elution volume and the distance of two subsequent peaks of a homologous series. From the intercept of the regression lines in such a plot the accessible volume can be easily determined at any mobile phase in LAC (corresponding to conditions of weak or strong adsorption) without any information about the molar mass of the peaks. From the slope of this dependence the adsorption interaction parameter of a given repeat unit can be obtained. The accurate determination of the accessible volume and the adsorption interaction parameter in the LAC regime is presented for PEG, PPG and fatty alcohols on various reversed phase columns with different pore size in methanol-water or acetone-water mobile phases. The difference between the void volume, the dead volume or hold-up volume (from the solvent peak position) and the accessible volume (obtained by this procedure) is discussed.
authors.affiliation: Institute of Chemistry, Karl-Franzens-Universiy, A-8010 Graz, Austria. bernd.trathnigg@uni-graz.at
authors.forename: Bernd
authors.initials: B
authors.lastname: Trathnigg
authors.forename: Alexander
authors.initials: A
authors.lastname: Skvortsov
mesh_terms: D000327:Adsorption; D002853:Chromatography, Liquid / Q000295:instrumentation / Q000379:methods*; D008962:Models, Theoretical; D011092:Polyethylene Glycols / Q000302:isolation & purification; D011108:Polymers / Q000302:isolation & purification; D011409:Propylene Glycols / Q000302:isolation & purification
chemical_list: D011108:Polymers; D011409:Propylene Glycols; C012504:polypropylene glycol; D011092:Polyethylene Glycols