Reagents and Solutions
All chemicals obtained from commercial sources were
of super pure grade unless otherwise stated. Freshly prepared
doubled distilled water, from a quartz still, was used in all experiments. The copper stock solution, 1000 mg/l was prepared fromcopper(II) nitrate (Sigma Chem. Co., St. Louis) in
10-3
MHNO3. Portions were diluted daily for obtaining reference and working solutions. Borate buffer solutions: 0.1 M
HCl solution was added dropwise to 0.05 M sodium tetra borate solution (Merck-Darmstadt) to the required pH.