1-Phenyl-2-(2-hydroxyphenylhydrazo)butane-1,3-dione (H2L) was used as an effective ionophore for copper-selective poly(vinyl) chloride (PVC) membrane electrodes. Optimization of the composition of the membrane and of the conditions of the analysis was performed, and under the optimized conditions the electrode has a detection limit of 6.30 x 10(-7) M Cu(II) at pH 4.0 with response time 10 s and displays a linear EMF versus log[Cu2+] response over the concentration range 2.0 x 10(-6) to 5.0 x 10(-3) M Cu(II) with a Nernstian slope of 28.80 +/- 0.11 mV/decade over the pH range of 3.0-8.0. The sensor is stable for 9 weeks and exhibits good selectivity with respect to alkali, alkali earth and transition metal ions (e.g. Na+, K+, Ba2+, Ca2+, Zn2+, Cd2+, Co2+, Mn2+, Ni2+, Fe2+, Al3+) in the 3.0-8.0 pH range. It was successfully applied for the direct determination of copper(II) in zinc, aluminum and nickel based alloys, in soils polluted by oil, and as an indicator electrode for potentiometric titration of copper ions with EDTA. (C) 2010 Elsevier B.V. All rights reserved.