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Determination of Ferric Cations by Potentiometric Sensors Modified with Different Metal Oxides and Oxyhydroxides Nanoparticles

Ion-selective electrodes represent electrochemical sensor that can determine ion activity in various samples, and often are modified with different kinds of metal nanomaterials. Solid-state ion- selective electrode represented here, are based on FePO4 : Ag2S : PTFE = 1:1:2 with addition of (0, 25-1)% microwave synthesized hematite, magnetite, boehmite or aluminium oxide nanoparticles, characterized with FTIR and SEM with EDS analysis, and investigated in order to establish ideal membrane composition for ferric cations determination. Membrane testing were performed in ferric cation solutions at pH values 1 and 5 and different effects occurred in dependence of percentage and type of nanoparticles in sensor composition. M1 with addition of 0, 25% aluminium oxide nanoparticles showed linear response towards ferric cations in the range from 6, 25·10-4 to 1·10-2 molL-1 with slope of -21, 725 mV per concentration decade and correlation factor R2=0, 9635. Increased share of aluminium oxide nanoparticles in membrane M2 (0, 5%) had a positive effect on the expansion of the linear dynamic range for almost a whole decade (3, 91·10-5-1·10-2 ; slope=-16, 77 ; R2=0, 9608). Iron oxide nanoparticles, magnetite, in 0, 25% share in membrane M3 at pH 1 showed very positive effect on linear dynamic range of ferric cations determination (2, 44·10-6-1·10-2 molL-1 ; slope=-22, 381 ; R2=0, 9853). Hematite in only 0, 25% addition (M4) had the most significant impact on ferric cation determination in range from 1, 2·10-6 to 10-2 with slope of -19, 753 mV per decade, almost identical with theoretical Nernstian slope for trivalent cations and R2=0, 9925. High arithmetic middle of recovery values (102, 8%) in ferric determination in standard solution confirmed wide applicability.

potentiometry, ion-selective electrodes, nanoparticles

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