Metal ion selective sensors based on molecularly imprinted polymers

The requirement for a chemical sensor to be highly selective for its target analyte in a matrix of other chemicals is an ongoing challenge. As a consequence of their stability and selectivity advantages, the applications of molecularly imprinted materials as artificial recognition elements in sensing devices is currently an area of intense interest; The dissertation presented here is directed toward the use of metal ion imprinted polymers as sensing elements in ion selective sensors. Lead(II) and Uranyl ions are chosen as target ions due to their well-known toxicity and environmental hazard. The technique of molecular imprinting allows the creation of selective binding sites in synthetic polymers by the use of an imprinting molecule to organize polymerizable monomers prior to their polymerization. Subsequent removal of the imprinting molecule leaves sites of cavities in the polymer that match the original imprinting molecule. Ion selective membrane electrodes based on these polymers can then be prepared. The enhanced selectivity of the sensors toward imprinting ion is achieved.; In this research, Metal ion selective sensors based on synthesized imprinted polymers have been constructed and evaluated. The lead(II) ion selective electrode exhibits a linear response towards lead(II) ion within the concentration range of 1 x 10-6--1 x 10-1 M of Pb(II) ion with a slope of 33 mV per decade. The detection limit of the electrode is found to be 1.5 x 10-6 M of Pb(II) ion. The uranyl ion selective electrode has a linear response to uranyl ion ranging from 1 x 10-7 to 1 x 10-2 M with a slope of 28 mV. A remarkable feature for uranyl ion electrode is that the electrode shows almost no response to Ca(II), Cu(II), Pb(II), Zn(II), Ni(II), Cd(II) Na(I) and La(III) ions. Selectivity coefficients of both electrodes were determined by various methods. The effects of pH and the composition of the membrane, and the longevity of the electrodes were also studied.