Optimisation of procedures for the extraction of structural analogues of propranolol with molecular imprinted polymers for sample preparation

A propranolol-derived molecular imprinted polymer (MIP) was prepared using methacrylic acid as monomer and ethylene glycol dimethacrylate as cross-lin ker. The extraction properties of five compounds structurally related to pr opranolol were assessed on the MIP and on a blank polymer made under the sa me conditions but in the absence of an imprint molecule. Using application from aqueous solution with methanol-water-triethylamine (TEA)-based solvent s for elution (i.e. reversed-phase conditions) the MIP showed only marginal selectivity for the compounds on the MIP compared to the blank. Despite th e limited selectivity there did appear to be a relationship between structu re of the compound (relative to propranolol) and the extent of selective re tention. Application of the compounds in toluene with elution using toluene -TEA or toluene-trifluoroacetic acid resulted in the MIP showing dramatical ly enhanced retention and selectivity of the compounds on the MIP compared to the blank. The enhanced selectivity for extraction on to the MIP relativ e to the blank, for all compounds using normal-phase solvents seem to be a class effect as there was no apparent relationship between compound structu re and retention. (C) 2000 Elsevier Science B.V. All rights reserved.