Potentiometric determination of potassium cations using a nickel(II) hexacyanoferrate-modified electrode

Electroactive nickel(II) hexacyanoferrate (NiHCF) thin him modified electro des are effective potentiometric sensors for the determination of potassium ions. The NiHCF films are deposited onto glassy carbon electrodes by repet itive potential cycling in K3Fe(CN)(6)/NaNO3/Ni(NO3)(2) solution. The modif ied electrodes exhibit a linear response to potassium ions in the concentra tion range 1 x 10(-3) to 2.0 mol dm(-3), with a near-Nernstian slope (45-49 mV per decade) at 25 degrees C. In the determination of potassium ion in s yrups used for treatment of potassium deficiency, the NiHCF-modified electr ode gave comparable results to those obtained using flame emission spectrop hotometry. (C) 1999 Elsevier Science B.V. All rights reserved.