Tandem Preconcentration of Cobalt by On-line Ion Exchange and Gas Phase Chelates Generated by Merging-zones Flow Injection Analysis With Electrothermal Atomic Absorption Spectrometric Determination

Abstract

An automated combined method of on-line preconcentration of Co on Amberlite IR-120 resin was developed followed by the generation of volatile cobalt chelates (diethyldithiocarbamate and acetylacetonate) which are then vaporized with a thermospray device to obtain a second preconcentration stage with decomposition of the gas phase generated on the surface of a pre-heated graphite platform with subsequent determination by ETAAS. The use of a by-pass valve between the thermospray device and the graphite chamber makes it possible to overcome the classical problems caused by condensation of the eluates. The sensitivity (0.0044 A s) achieved by the proposed tandem preconcentration–ETAAS method is 0.8 and 1.1 ng l^–1 with a detection limit (3σ) of 2 and 3 ng l^–1 for cobalt diethyldithiocarbamate and cobalt acetylacetonate, respectively. The method was evaluated against unpolluted certified reference natural waters and satisfactory results were obtained.

References

1. R. Boniforti, R. Ferraroli, P. Frigieri, D. Heltai and Q. Queirazza, Anal. Chim. Acta, 1984, 162, 33.
2. S. Nakashima, R. E. Sturgeon, S. N. Willie and S. S. Berman, Fresenius' Z. Anal. Chem., 1988, 330, 592.
3. J. W. McLaren, A. P. Mykytiuk, S. N. Willie and S. S. Berman, Anal. Chem., 1985, 57, 2907.
4. K. Isshiki and E. Nakayama, Anal. Chem., 1987, 59, 291.
5. M. Sperling, X. Yin and B. Welz, J. Anal. At. Spectrom., 1991, 6, 615.
6. K. Bächmann, Talanta, 1982, 29, 1.
7. J. Ashby and P. J. Craig, Sci. Total Environ., 1989, 78, 219.
8. W. R. Wolf, Anal. Chem., 1976, 48, 1713.
9. M. S. Black, M. B. Thomas and R. F. Browner, Anal. Chem., 1981, 53, 2224.
10. M. S. Black and R. F. Browner, Anal. Chem., 1981, 53, 249.
11. R. W. Moshier and R. E. Sievers, Gas Chromatography of Metal Chelates, Pergamon Press, New York, 1965.
12. A. Tavlaridis and R. Need, Fresenius' Z. Anal. Chem., 1978, 292, 135.
13. R. E. Sievers and J. E. Sadlowski, Science, 1978, 201, 217.
14. H. Schaler and R. Neeb, Fresenius' Z. Anal. Chem., 1986, 322, 473.
15. H. Meierer and R. Neeb, Fresenius' Z. Anal. Chem., 1983, 315, 422.
16. V. Gemmer-Colos and R. Neeb, Fresenius' Z. Anal. Chem., 1982, 311, 496.
17. W. R. Wolf, R. E. Sievers and G. H. Brown, Inorg. Chem., 1972, 11, 1995.
18. M. de la Guardia, A. R. Mauri and C. Mongay, J. Anal. At. Spectrom., 1988, 3, 1035.
19. Y. K. Chau, P. T. S. Wong and H. Saitoh, Anal. Chem., 1975, 47, 2279.
20. J. Alary, J. Vandaele and C. Escrieut, Talanta, 1986, 33, 748.
21. D. S. Lee, Anal. Chem., 1982, 54, 1182.
22. B. W. Bailey and F. C. Lo, Anal. Chem., 1972, 44, 1304.
23. D. C. Hilderbrand and E. E. Pickett, Anal. Chem., 1975, 47, 424.
24. W. R. Wolf, Anal. Chem., 1976, 48, 1717.
25. W. R. Wolf, J. Chromatogr., 1977, 134, 159.
26. D. A. Segar, Anal. Lett., 1974, 7, 89.
27. M. S. Black, Anal. Chem., 1981, 53, 249.
28. J. M. Mir, S. Orea, M. S. Jimenez and J. R. Castillo, Quim. Anal., 1992, 11, 45.
29. J. R. Castillo, J. Delfa, J. M. Mir, C. Bendicho, M. de la Guardia, A. R. Mauri, C. Mongay and E. Martinez, J. Anal. At. Spectrom., 1990, 5, 325.
30. M. S. Jiménez, J. M. Mir and J. R. Castillo, J. Anal. At. Spectrom., 1993, 8, 665.
31. J. M. Mir, M. S. Jiménez and J. R. Castillo, At. Spectrosc., 1995, 16, 127.
32. J. M. Mir, M. S. Jimenez and J. R. Castillo, Quim. Anal., 1996, 15, 255.
33. Z. L. Fang, J. Ruzicka and E. H. Hansen, Anal. Chim. Acta, 1984, 164, 23.
34. Z. Fang, Flow Injection Separation and Preconcentration, VCH, New York, 1993, pp. 15–18.
35. P. C. Bank, M. T. C. de Loos-Vollebregt and L. de Galan, Spectrochim. Acta, Part B, 1989, 44, 571.
36. D. L. Styris and D. A. Redfield, Spectrochim. Acta Rev., 1993, 15, 71.