A set of polymers has been imprinted with (−)-ephedrine at six different temperatures,
ranging from −30 to +80 °C. Polymer affinity and specificity were observed to be strongly dependent on
the polymerization temperature. The experimental results suggest that the polymer is able to “memorize”
the temperature used in the polymerization process in a manner similar to previously documented MIP
“memory” effects for the template and polymerization solvent. In a study of the effect of temperature on
retention and selectivity in HPLC (using the MIP as a column packing), a clear gradient change in the
Van't Hoff plots was observed at 20−30 °C. This indicates a transition in binding mechanism from
exothermic at higher temperatures to endothermic at lower temperatures. These results, supported by
the evidence of template-induced MIP swelling, are interpreted in terms of desolvation and conformational
changes in the polymers induced by the interaction with the template.
Pharmaceutical companies have a continuous need to resolve new racemates. Analysis may be required in aqueous and nonaqueous media, or in the presence of several different sets of potentially interfering compounds. There is often a preparative requirement. For these reasons analysts may require a number of different separation systems capable of resolving a given pair of enantiomers. We wished to improve upon existing approaches that address this situation and undertook a program of work to screen over 100 racemates, selected for their chemical diversity, on over 100 different chiral HPLC, SFC, and CE systems. Here we report results of this comparison and illustrate the use of rapid gradient screening as a valuable tool for chiral method development.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.