Differential pulse anodic stripping voltammetric determination of copper(II) with N-phenylcinnamohydroxamic acid modified carbon paste electrodes

Copper(II) was selectively accumulated, at open circuit, on a carbon paste electrode incorporating N-phenylcinnamohydroxamic acid. The ensuing measurements were carried out by differential pulse anodic stripping voltammetry. Factors affecting the accumulation, reduction, and stripping steps were investigated and a procedure was developed. Two linear ranges were obtained in the concentration ranges 1.00 x 10(-8) -1.00 x 10(-6) M Cu(II) with 3 min preconcentration time and 1 min reduction time and 1.00 x 10(-9) -1.00 x 10(-8) M Cu(II) with 10 min preconcentration time and 2 min reduction time. The detection limit was found to be 5.00 x 10(-10) M with 10 min accumulation and 2 min reduction time. For six successive determinations of 1.00 x 10(-8) and 5.00 x 10(-7) M Cu(II), relative standard deviations of 9.4 and 8.7%, respectively, were obtained. The modified electrode preferentially accumulates copper from the solution, while most of the metal ions do not interfere with the determination. The developed method was applied to copper determination in potable water and in commercial lithium chloride. (C) 1998 Elsevier Science B.V. All rights reserved.