Organic Solvent Modifier and Temperature Effects in Non-Aqueous Size-Exclusion Chromatography on Reversed-Phase Columns
Andre M. Striegel, Anna Caltabiano, Joe Foley
The effect of THF solvent and the mixtures of THF with a variety of common HPLC solvents (chloroform, acetone, 2-propanol, DMF, ethanol, acetonitrile and methanol) on reversed-phase stationary phase (C18, C4, phenyl and cyano) characteristics relevant to size exclusion were studied. Solvent effect on elution of polystyrene and poly(methyl methacrylate) and the effect of column temperature (within a relatively narrow range corresponding to typical chromatographic conditions, i.e., 10ºC - 60ºC) on partition coefficient of PS and PMMA polymers, KSEC, were also investigated. Common reversed-phase columns (C18, C4, phenyl and cyano) offer an inert surface suitable for the analysis of polymers by SEC. The bonded phases show remarkable differences in size separations when binary mixtures of THF with other solvents are used as the mobile phase. The solvent impact can be three fold: (i) change of the polymeric coil size, and possible shape, (ii) change of the stationary phase pore volume and (iii) change in the solvated stationary phase properties as it may become good or poor solvent for the solutes. If the effect of this impact is properly moderated, then the greatest benefit of optimized solute resolution can be achieved. Temperature effect is only realized in decreased elution volumes of polymers with the temperature increase. SEC partition coefficients are temperature independent in the range of 10ºC - 60ºC and therefore, elution of PS and PMMA polymers is by a near-ideal SEC on reversed-phase columns. Non-ideal SEC is possible for high molar mass PMMA polymers on a cyano column when alcohols are used as mobile phase modifiers.
, Caltabiano, A.
and Foley, J.
Organic Solvent Modifier and Temperature Effects in Non-Aqueous Size-Exclusion Chromatography on Reversed-Phase Columns, Journal of Chromatography A, [online], https://doi.org/10.1016/j.chroma.2017.11.027
(Accessed December 11, 2023)