The use of molecularly imprinted sol-gels in pharmaceutical separations.

This paper illustrates the potential of the sol-gel process to imprint the pharmaceutical active--N-[N-[(1S)-1-carboxssy-3-phenylpropyl]-l-lysyl]-L-proline, (lisinopril dihydrate). This template exhibits unique difficulties such as limited solubility in non-polar and most polar porogens with multiple functionality evident in its 4 pKa values. Selectivity for this template was achieved using a 3-monomer sol-gel system utilising solid phase extraction (SPE). Analysis of the template and its related substances was achieved using HPLC. The effect of solvent polarity on the rebinding of the template was studied. Through optimisation of porogen and extraction solvent, the imprinted material (MIP) demonstrated enhanced selectivity, for the template, over a non-imprinted material (NIP). Selectivity was also illustrated for the original template over two of its related substances. The effect of starting monomer ratio on selectivity was studied to determine the interactions, which could best be exploited to further enhance selectivity.