A Comparison of the Retention of Homologous Series and Other Test Solutes on an Ods Column and a Hypercarb Carbon Column

Abstract

When compared with an ODS column having good surface coverage and operated with pure methanole eluent, the Hypercarb column exhibits similarities in some respects and dissimilarities in others. Methylene homologues separations look similar on ODS and on Hypercarb. Their In k' increase linearly with carbon number, although much steeper on Hypercarb. The free sorption enthalpy of methylene groups is about three times higher on the carbon column. The apparent phase ratio is lower with Hypercarb by a factor of about 100. Consequently, the retention of smaller size solutes is lower than on ODS, and the sample load capacity is smaller, too. n-Alkanes and other long chain alkyl compounds exhibit an unusual behavior on Hypercarb. With increasing sample size, their peaks show a strongly fronting profile, possibly indicating a change in ret-