Mimicking a Receptor for Cyanide Ion Based on Ion Imprinting and Its Applications in Potential Transduction

Using the strategy of template polymerization, a presynthesized specific metal-complexing polymer (poly(methacryloylhistidine-Ni(II)-CN-), Ni-CN/IP) has been specifically used to recognize cyanide ion. As described previously, nickel(II)-methacryloylhistidine dihydrate complex monomer was synthesized and reacted with KCN to produce the monomer-template complex. This monomer-template complex phase was polymerized in a dispersion medium. After polymerization, the template (CN-) was removed from the Ni-CN/IP, producing CN- ion imprinted metal-chelate polymer. The synthesized ion imprinted polymer is examined as a novel potential cyanide selective ionophore in polymeric membrane type ion selective electrodes. Membranes formulated with Ni-CN/IP are shown to exhibit enhanced potentiometric selectivity for cyanide over more lipophilic anions including perchlorate, iodide, and thiocyanate. Addition of lipophilic cationic sites into the organic membranes enhanced the response and selectivity towards CN- ion, while addition of lipophilic anionic sites deteriorated the response but enhanced the selectivity, indicating that the Ni-CN/IP particles behaves via the so-called mixed-mode response mechanism. The fabricated sensors possessed good performance characteristics, in terms of life span, selectivity for CN- ion over a wide range of other interfering anions, fast response, stability and high reproducibility. Applications for direct determination of cyanide ion in hazardous wastes using the proposed sensors showed good correlation with data obtained using commercial solid state cyanide electrode, with no significant difference in the t-test values with 95?% confidence level. An F-test revealed that the standard deviations of the replicate sample measurements obtained by the two methods were not significantly different.