Cloud point preconcentration and flame atomic absorption spectrometry: application to the determination of nickel and zinc

Abstract

A simple and versatile method for the preconcentration of trace amounts of nickel and zinc is proposed. The method, which does not require the use of organic solvents, is based on the phase separation phenomenon undergone by aqueous solutions of non-ionic surfactants and can be used as a prior step to the determination of these elements by flame atomic absorption spectrometry. 1-(2-Pyridylazo)-2-naphthol (PAN) and Triton X-114 were used as hydrophobic ligand and non-ionic surfactant, respectively. The chemical variables affecting the separation phase and the viscosity affecting the detection process were optimized. Under the experimental conditions used, preconcentration of only 10 ml of sample in the presence of 0.1% Triton X-114 permitted the detection of 8 ppb of zinc and 6 ppb of nickel. The proposed procedure was applied to the determination of both ions in different water samples.

References

1. M. Corti, V. Degiorgio, J. B. Hayter and M. Zalauf, Chem. Phys. Lett., 1984, 109, 579.
2. V. Degiorgio, R. Piazza, M. Corti and C. J. Minero, Chem. Phys., 1985, 82, 1025.
3. D. Blankschtein, G. M. Thurston and G. B. Benedek, J. Chem. Phys., 1986, 85, 7268.
4. B. Lindman and H. Wennerstrom, J. Phys. Chem., 1991, 95, 6053.
5. T. Saitoh and W. L. Hinze, Anal. Chem., 1991, 63, 2520.
6. C. García Pinto, J. L. Pérez Pavón and B. Moreno Cordero, Anal. Chem., 1992, 64, 2234.
7. B. Moreno Cordero, J. L. Pérez Pavón, C. García Pinto and M. E. Fernández Laespada, Talanta, 1993, 40, 1703.
8. A. Bockelen and R. Niessner, Fresenius J. Anal. Chem., 1993, 346, 435.
9. C. García Pinto, J. L. Pérez Pavón and B. Moreno Cordero, Anal. Chem., 1994, 66, 874.
10. C. García Pinto, J. L. Pérez Pavón and B. Moreno Cordero, Anal. Chem., 1995, 67, 2606.
11. H. Watanabe, in Solution Behavior of Surfactants, ed. Mittal, K. L., and Fendler, E. F., Plenum Press, New York, 1982, vol. 2, p. 1305.
12. H. Watanabe and H. Tanaka, Talanta, 1978, 25, 585.
13. S. Kwamorita, H. Watanabe and K. Haraguchi, Anal. Sci., 1985, 1, 41.
14. T. Saitoh, Y. Kimura, T. Kamidate, H. Watanabe and K. Haraguchi, Anal. Sci., 1985, 1, 41.
15. E. Pramauro, C. Minero and E. Pelizzeti, in Ordered Media in Chemical Separations, ed. Hinze, W. L., and Armstrong, D., ACS Symposium Series 342, American Chemical Society, Washington, DC, 1987, ch. 7.
16. T. Saitoh, Y. Kimura, H. Kamidate, H. Watanabe and K. Haraguchi, Anal. Sci., 1989, 5, 577.
17. E. Pramauro, Ann. Chim. (Rome), 1990, 80, 101.
18. M. E. Fernández Laespada, J. L. Pérez Pavón and B. Moreno Cordero, Analyst, 1993, 118, 209.
19. C. García Pinto, J. L. Pérez Pavón, B. Moreno Cordero, E. Romero Beato and S. García Sánchez, J. Anal. At. Spectrom., 1996, 11, 37.
20. M. F. Silva, L. Fernandez, R. A. Olsina and D. Stacchiola, Anal. Chim. Acta, 1997, 342, 229.
21. W. L. Hinze and E. Pramauro, Crit. Rev. Anal. Chem., 1993, 24, 133.
22. H. Tani, T. Kamidate and H. Watanabe, J. Chromatogr. A, 1997, 780, 229.
23. W. E. Johnson, N. J. Fendinger and J. R. Plimmer, Anal. Chem., 1991, 63, 1510.
24. O. Royset, Anal. Chim. Acta, 1986, 185, 75.