Application and elution conditions for the selective elution of analytes from molecular imprinted polymers after extraction from aqueous samples:: Application to β-blockers

Three propranolol-derived MIPs were investigated as selective sorbents for the solid phase extraction of beta -blockers. Initial evaluation of these MIPs with aqueous-based elution solvents revealed little or no selectivity for propranolol analogues compared to a blank polymer. Where a little selectivity was evident with one of the polymers ii was possible to relate this to the structure of the analogues relative to propranolol. Further studies with this minimally selective MIP with application and elution using toluene-based solvents revealed significant selective extraction compared to the blank polymer. However, under these conditions ail the analogues showed a similar level of selectivity with extraction appearing to be class-rather than structure-related. This effect was also seen for those MIPs showing no selectivity with aqueous solvents. Following on from these observations extraction conditions were then developed to provide selective extraction from aqueous samples.