Highly selective and sensitive copper membrane electrode based on a new synthesized Schiff base

Bis(2-hydroxyacetophenone)butane-2,3-dihydrazone (BHAB) was used as new N-N Schiffs base which plays the role of an excellent ion carrier in the construction of a Cu(II) membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 55% o-nitrophenyloctyl ether (NPOE), 7% BHAB and 8% oleic acid (OA). This sensor shows very good selectivity and sensitivity towards copper ion over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The effect of membrane composition and pH and influence of additive anionic on the response properties of electrode were investigated. The electrode exhibits a Nernstian behavior (with slope of 29.6 mV per decade) over a very wide concentration range (5.0 × 10⁻⁸ to 1.0 × 10⁻² mol L⁻¹) with a detection limit of 3.0 × 10⁻⁸ mol L⁻¹ (2.56 ng mL⁻¹). It shows relatively fast response time, in whole concentration range (<15 s), and can be used for at least 12 weeks in the pH range of 2.8-5.8. The proposed sensor was successfully used to determination of copper in different water samples and as indicator electrode in potentiometric titration of copper ion with EDTA.