Imprinted polymers for chiral resolution of (±)-ephedrine, 4: packed column supercritical fluid chromatography using molecularly imprinted chiral stationary phases.

(-)-Ephedrine-molecularly imprinted polymers (MIPs) have been successfully used as stationary phases in supercritical fluid chromatography for the separation of (±)-ephedrine enantiomers. This approach combines the simple preparation and predictable elution order of MIP stationary phases with the superior mobile phase diffusivity and low viscosity of supercritical fluid mobile phases. The optimised mobile phase comprised supercritical carbon dioxide with a modifier consisting of MeOH/isopropylamine/H(2)O 93:5:2 (v/v/v).

Imprinted polymers for chiral resolution of +/--ephedrine. Part 2: Probing pre-polymerisation equilibria in different solvents by NMR.

A sophisticated analysis of the pre-polymerisation association of monomer and template for the molecular imprinting of (-)-ephedrine (template) using methacrylic acid (monomer) has been performed using NMR titrations and data analysis with the computer program HypNMR. The fitted model takes account of the dimerisation of monomer, and 1 : 1, 2 : 1 and 3 : 1 monomer-template complexes. Values for the association constants and chemical shifts of the different nuclei in the various species are generated quickly and simply.