REORDERING/RESOLVATION STUDIES OF ALKYLAMIDE PHASES

A series of chemically bonded liquid chromatographic packings containing a specific interaction site localized in the interior region of the attached ligands has been prepared by a two-step synthetic route. In the first-step an amino phase is formed and then it is converted to an alkylamide group via reaction with an acid chloride. Using this procedure materials have been prepared with immobilized terminal alkyl groups with chain lengths ranging from C-5 to C-8. Subsequently, the conformation of these modified surfaces have been investigated as a function of temperature under totally aqueous mobile phase conditions. Plots of In k' vs. 1/T curves have been found to be similar to those reported for alkyl phases. However, the onset of reordering/resolvation of the attached ligands is shifted to lower temperatures and the incremental change per methylene group is smaller.