Molecularly imprinted polymers (MIP) are a new generation of selective adsorbents. In practical applications of MIPs
Keywords molecularly imprinted polymer, adsorption isotherm, competitive adsorption isotherm, propranolol, beta blocker
IntroductionMolecularly imprinted polymers (MIP) are a new generation of selective adsorbents. They are the subject of vigorous research which produces hundreds of papers annually. After years of fundamental research the time appears to be ripe now for their practical applications. This is attested by the increasing number of patent applications (62 in MIPs are typically made by polymerization of suitable monomers in the presence of a so-called template compound. After polymerization the template is removed from the polymer. This procedure leaves empty binding sites in the polymer, which are chemical and geometrical imprints of the template molecule. Due to these sites the MIP can rebind from solutions the template or other molecules which are chemically related to the template. The rebinding on a good MIP occurs selectively against compounds which are not very closely related to the template. The target compound of a practical application can be either the template or a closely related compound (e.g. if the template is expensive or toxic or its bleeding would disturb). Eventually a group of closely related compounds to the template may be targeted.For successful practical applications one needs to know if the MIP will show sufficient selectivity. Quantification of selectivity is a difficult problem in chemistry, and particularly in analytical chemistry [20][21][22][23][24][25]. In the case of MIPs one may rely on a large body of experience in relation to chromatographic adsorbents. The selectivity of liquid chromatographic stationary phases is easily characterized (in a given eluent) if the adsorption isotherms of all adsorbed solutes are linear. In this case selectivity between two adsorbable compounds can be given by the ratio of the respective isotherm slopes, i.e., by the ratio of the respective,