Determination of Ni۲+ in aqueous solution by ion selective electrode at screen printed electrode modified by ion imprinted polymer

For many decades, nickel was regarded as a potentially toxic element, since its concentrationin various foods was higher than that needed for living organisms. More recently, it is now considered apossible essential element for plants, although deficiencies can occur under certain circumstances.However, nickel can be toxic at high concentrations and can be a problem in some soils. Hence the needfor nickel ion determination in clinical and food analysis and environmental monitoring has led to anumber of methods for the measurement of this analyte [۱].The Nickle ion-imprinted polymerparticles(IIP) were synthesized via single pot method by dissolving of ternary complex of Nickle with ۵,۷-Dichloroquinoline-۸-ol (DCQ) and ۴-vinyl pyridine (VP) in acetonitrile (porogen) and copolymerizedthermally after addition of methyl methacrylate (monomer) and ethylene glycoldimethacrylate(crosslinking monomer) in the presence of ۲,۲-azobisisobutyronitrile (initiator). The bare screen printedelectrode were prepared and constructed according to the procedure described elsewhere [۲].Thechemically modified screen printed electrode electrodes were prepared by thoroughly mixing of PVC,NPOE, NaTPB and nickle IIP particles (۶۰–۸۵μm size ) in proportions of ۲۷, ۵۳, ۵ and ۱۵% (w/w),respectively and dispersed in ۲.۵ ml of tetrahydrofuran (THF). The mixture was homogenized in asonicator and then poured into a watch glass. The THF solvent was allowed to evaporate at roomtemperature to obtain a viscose mixture, to cover the screen printed electrode surface. The solvent wasallowed to evaporate to thin PVC film formed on the screen printed electrode surface. The plot obtainedfor the sensor with Nickle IIP particles showed a slope of ۲۹.۲ mV per decade over a concentration rangeof ۵.۰×۱۰−۶ to ۱.۰×۱۰−۴M of Nickle is the expected Nernstian slope for the divalent cations. The limit ofdetection was ۱×۱۰−۷M Nickle calculated based on the IUPAC definition. However, the electrode with theblank membrane showed no response for Ni ion in the concentration range ۵.۰×۱۰−۶ to ۱.۰×۱۰−۴M. Theelectrode was used in the direct determination of Ni۲+ in aqueous solution. Selectivity parameter data forvarious ions are presented in table .۱.