Four electrodes with liquid membrane, Cu2+-selective and Ni2+-selective, not previously described in the literature, were prepared and characterized. Electrodes 1 and 2 are based on mixed complexes of Cu(II) and Ni(II) with isonicotinoylhydrazone-2-aldehydepyrrole (INH2AP = HL1) as ligand and electrodes 3 and 4 are based on the mixed complexes with isonicotinoyl-hydrazone-2-hydroxy-1-naphthaldehyde (INH2HNA = H2L2). Cu2+- selective and Ni2+- selective electrodes have been used to determine the copper and nickel ions in aqueous solutions, by both direct potentiometric and potentiometric titration with EDTA. They have also been used for determining the Cu2+and Ni2+ ions in industrial waters by direct potentiometry. The analytical results obtained have been checked by the standard addition method and by comparison with determinations through atomic absorption spectrometry.

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