DETERMINATON AND SPECIATION OF COPPER IN NATURAL WATERS BY SQUARE WAVE ANODIC STRIPPING VOLTAMMETRY

Ali Bazzi*, Donna Hollandsworth, and Nicholas Irish, Department of Natural Sciences, University of Michigan - Dearborn, Dearborn, MI 48128-1491, U.S.A.

e-mail: abazzi@sb-f1.umd.umich.edu, phone: (313) 593-5367, fax: (313) 593-4937

Jerome Nriagu, Department of Environmental and Industrial Health, School of Public Health, University of Michigan, Ann Arbor, MI 48109-2029, U.S.A.

Although square wave voltammetry (SWV) has been reported to be more sensitive than differential pulse techniques by a factor of 2 to 4, most of the speciation and analysis studies of natural waters for heavy metals by electrochemical methods have been done using differential pulse anodic stripping voltammetry (DPASV). In this presentation, we report on the determination of total dissolved copper in samples taken from Saginaw Bay, Michigan, USA, by square wave anodic stripping voltammetry (SWASV) using a hanging mercury drop electrode (HMDE). Samples were analyzed for total dissolved copper after filtration and proper digestion with ultra pure nitric acid using standard addition technique. Analyses were carried out with a deposition time of 15 min at a deposition potential, E_d , of -0.75 V vs. Ag/AgC1. Values ranging from 5.11 to 19.73 nM of copper were obtained from different stations and at various depths. Voltammetric titrations using SWASV with HMDE to evaluate complexation capacity, conditional stability constant, and copper speciation are currently being carried out in our laboratory. A mechanism to explain extra peak phenomenon observed during voltammetric titrations and when investigating incubated natural water samples by SWASV will also be proposed.