The Malaysian Journal of Analytical Sciences Vol 12 No 2 (2008): 384 – 396
DETERMINATION OF SUB – PARTS PER BILLION LEVELS OF COPPER IN COMPLEX MATRICES BY ADSORPTIVE STRING VOLTAMMERY ON A MERCURY ELECTRODE
H. R. Shahbaazi1, 2, A. Safavi2, and N. Maleki2
1Department of Chemistry, Islamic Azad University of Varamin Branch,
Varamin, Iran.
2Department of Chemistry, College of Sciences, Shiraz University,
Shiraz, 71454, Iran.
Abstract
The voltammetric characteristics of Cu(II)-SSA complex at the mercury electrode were investigated. An analytical method that based on the adsorptive accumulation of Cu(II)-SSA complex followed by the reduction of the complexed copper was developed for copper determination in complex matrices in presence of the large amount of foreign ions. Adsorptive voltammetry determinations showed that the Cu(II)-SSA complex behaves irreversibly exchanging two electrons on the hanging mercury drop electrode (HMDE). Factor affecting on the complextion, accumulation, and stripping steps were studied and a procedure was developed. The instrumental parameters in the measurement step were also tested. The optimum conditions of pH, SSA concentration, accumulation potential and accumulation time were studied. Under optimal conditions (pH= 12.9 glycin Buffer, 7×10-3 M SSA and accumulation potential -100 mV vs. Ag/AgCl), a linear calibration graph in the range 1.25 mg L-1 to 42.5 mg L-1 and a detection limit of 0.8 mg L-1 were obtained. The average relative standard deviation (RSD) for seven determinations was calculated as 7%, 5.5% and 3% for the concentrations between 3, 15 and 23 mg L-1. The effect of foreign ions and surfactants on the peak height of Cu(II)-SSA complex was evaluated. The method was applied for the determination of the copper in different real samples such as crude oil, crude oil tank button sludge, wastewater and tap water samples. The accuracy of the results was checked by ICP.
Keywords: Copper, sulfosalicylic acid (SSA), adsorptive stripping voltammetry, sludge
1. D.G. Barceloux, Copper, Clin. Toxicol. 37 (1999) 217.
2. J. Wang, Stripping Analysis: Principles, Instrumentation and Applications, VCH, Deerfield Beach, 1985.
3. E.P. Gill, R.M. Garcia, A.S. Misiego, Anal. Chim. Acta, 1995, 315, 69.
4. M. Esteban, E. Casassas, Stripping electroanalytical techniques in environmental analysis, Trends Anal. Chem. 13 (1994) 110.
5. Kh. Brainina, E. Neyman, Electroanalytical Stripping Methods, Wiley, New York, 1993.
6. F. Vydra, K. Stulik, E. Juláková, Electrochemical Stripping Analysis, Ellis Horwood, Chichester, 1976.
7. Kh. Brainina, Stripping Voltammetry in Chemical Analysis, Halsted, New York, 1974.
8. R. Kalvoda, Electroanalytical Methods in Chemical and Environmental Analysis, Plenum Press, New York, 1987.
9. P.T. Kissinger, W.R. Heineman (Eds.), Laboratory Techniques in Electroanalytical Chemistry, Marcel Dekker, New York, 1984.
10. Mannino, S., Wang, J., Electroanalysis, 1992, 4, 835.
11. Ana Herrero, M. Cruz Ortiz, Talanta Volume 49, Issue 4 , 12 July 1999, Pages 801.
12. Kh. Z. Brainina, Talanta 1971, 18, 513.
13. R. Kalvoda, Anal. Chim. Acta 1982, 138, 11. C. M. G. van den Berg, Analyst 1989, 114, 1527.
14. C. M. G. van den Berg, Anal. Chim. Acta 1991, 250, 265.
15. A. Safavi, N. Maleki, E. Shams, H.R. Shahbaazi, Electroanalysis 14(13) (2002) 929.
16. A.A. Ensafi, S. Abbasi, H. Rahimi Mansour, I. Mohammadpour Baltork, Analtical Sciences, May 2001, Vol. 17, 609.
17. Ju. Lurie, Handbook of Analytical Chemistry, Printed in the Union of Soviet Socialist Republics, 1975.
18. USEPA U.S Environmental Protection Agency (http://www.epa.gov/)
19. E. Laviron, J. Electroanal. Chem. 1974, 52, 355.
20. A. Safavi, N. Maleki, H.R. Shahbaazi, Anal. Chim. Acta, 494 (2003) 225.
21. Bard, A. J.; Faulkner, L. R. Electrochemical methods. Fundamentals and Application; Wiley: New York, 1980.
22. J.C. Miller, J.N. Miller Statistics for Analytical Chemistry, 2nd ed, Ellis Horwood Ltd, Chichester, England, 1992.