Interferences during mercury speciation determination by volatilization, cryofocusing, gas chromatography and atomic absorption spectroscopy: comparative study between hydride generation and ethylation techniques

Abstract

The interfering effects of sodium chloride and a mixture of metal ions on the speciation determination of mercury by derivatization (hydride generation or ethylation), preconcentration by cryotrapping, gas chromatographic separation and detection by quartz furnace atomic absorption spectroscopy were investigated. The potential of the masking agent EDTA to overcome the interference was also studied. The experiments were arranged according to a 2ⁿ+1 factorial experimental design, so the possibility of synergistic effects among the variables considered was also taken into account. NaCl interferes in the determination of methylmercury (MeHg⁺) by ethylation, but causes fewer problems in the case of inorganic mercury (Hg²⁺) or if the analysis is carried out by hydride generation. The presence of metal ions strongly decreases the sensitivity in the determination of both compounds by hydride generation, but has no effect if ethylation is used as the derivatization technique. EDTA only partially eliminates the interfering effect of metals in the determination of MeHg⁺ by hydride generation. It also avoids decomposition of MeHg⁺ to Hg⁰ , promoted by NaCl, after derivatization of the compounds by hydride generation. The results obtained are discussed in terms of a comparison between the two derivatization techniques used, i.e., hydride generation and ethylation. Potential chemical pathways and reaction mechanisms for the observed interferences are also given.

References

1. J. O. Nriagu and J. M. Pacyna, Nature (London), 1988, 333, 134.
2. T. W. Clarkson, R. Hamada and L. Amin-Zaki, in Changing Metals Cycles and Human Health, ed. Nriagu, J. O., Springer, Berlin, 1984, pp. 285–309.
3. P. J. Craig, in Organometallic Compounds in the Environment, Principles and Reactions, ed. Craig, P. J., Longman, Harlow, 1986, pp. 65–101.
4. W. P. Ridley, L. J. Dizikes and J. M. Wood, Science, 1977, 197, 329.
5. M. Bernhard and M. O. Andreae, in Changing Metals Cycles and Human Health, ed. Nriagu, J. O., Springer, Berlin, 1984, pp. 143–167.
6. A. Kudo and S. Miyahara, Water Sci. Technol., 1991, 23, 283.
7. R. Puk and J. H. Weber, Appl. Organomet. Chem., 1994, 8, 293.
8. D. L. Collett, D. E. Fleming and G. A. Taylor, Analyst, 1980, 10, 897.
9. M. Horvat, K. May, M. Stoeppler and A. R. Byrne, Appl. Organomet. Chem., 1988, 2, 515.
10. M. Horvat, N. S. Bloom and L. Liang, Anal. Chim. Acta, 1993, 281, 135.
11. H. Emteborg, E. Böjrklund, F. Ödman, L. Karlsson, L. Mathiasson, W. Frech and D. Baxter, Analyst, 1996, 121, 19.
12. Ph. Quevauviller, G. U. Fortunati, M. Filipelli, M. Baldi and H. Muntau, Appl. Organomet. Chem., 1996, 10, 537.
13. K. May, M. Stoeppler and K. Reisinger, Toxicol. Environ. Chem., 1987, 13, 153.
14. N. S. Bloom, Can. J. Fish. Aquat. Sci., 1989, 46, 1131.
15. L. Liang, M. Horvat, E. Cernichiari, B. Gelein and S. Balogh, Talanta, 1996, 43, 1883.
16. R. Fisher, S. Rapsomanikis and M. O. Andreae, Anal. Chem., 1993, 65, 763.
17. R. Puk and J. H. Weber, Anal. Chim. Acta, 1994, 292, 175.
18. C. M. Tseng, A. de Diego, F. M. Martin and O. F. X. Donard, J. Anal. At. Spectrom., 1997, 12, 629.
19. C. M. Tseng, A. de Diego, F. M. Martin, D. Amouroux and O. F. X. Donard, J. Anal. At. Spectrom., 1997, 12, 743.
20. G. Westöö, Acta Chem. Scand., 1966, 20, 2131.
21. G. Westöö, Acta Chem. Scand., 1967, 21, 1790.
22. W. Holak, Analyst, 1982, 107, 1457.
23. M. Filipelli, Anal. Chem., 1987, 59, 116.
24. K. G. Robinson and M. S. Shuman, Int. J. Environ. Anal. Chem., 1989, 36, 111.
25. N. S. Bloom, Can. J. Fish. Aquat. Sci., 1992, 49, 1010.
26. W. Jian and C. W. McLeod, Talanta, 1992, 39, 1537.
27. R. Ritsema and O. F. X. Donard, Appl. Organomet. Chem., 1994, 8, 571.
28. C.-W. Huang and S.-J. Jiang, J. Anal. At. Spectrom., 1993, 8, 681.
29. M. Horvat and A. R. Byrne, Talanta, 1990, 2, 207.
30. BORWIN, Logiciel Intuitif pour la Chromatographie, Version 1.2, JMBS Developpements, Grenoble, France, 1994.
31. J. C. Miller and J. N. Miller, Statistics for Analytical Chemistry, Ellis Horwood, Chichester, 1984.
32. A. D. Campbell, Pure Appl. Chem., 1992, 64, 227.
33. J. Dedina, Anal. Chem., 1982, 54, 2097.
34. R. Belcher, S. L. Bogdanski, E. Henden and A. Townshend, Analyst, 1975, 100, 522.
35. J. E. Drinkwater, Analyst, 1976, 101, 672.
36. E. O. Uthus, M. E. Collings, W. E. Cornatzer and F. H. Nielsen, Anal. Chem., 1981, 53, 2221.
37. K. Jin, H. Terada and M. Taga, Bull. Chem. Soc. Jpn., 1981, 54, 2934.
38. E. Henden, Analyst, 1982, 107, 872.
39. I. Z. Al-Zamil and A. Townshend, Anal. Chim. Acta, 1988, 209, 275.
40. F. M. Martin and O. F. X. Donard, J. Anal. At. Spectrom., 1994, 9, 1143.
41. F. M. Martin, C. M. Tseng, C. Belin, P. Quevauviller and O. F. X. Donard, Anal. Chim. Acta, 1994, 286, 343.
42. S. Rapsomanikis and P. J. Craig, Anal. Chim. Acta, 1991, 248, 563.
43. S. Rapsomanikis, Analyst, 1994, 119, 1429.
44. A. E. Smith, Analyst, 1975, 100, 300.
45. G. F. Kirkbright and M. Taddia, Anal. Chim. Acta, 1978, 100, 145.
46. B. Welz and M. Melcher, Analyst, 1984, 109, 569.
47. B. Welz and M. Melcher, Analyst, 1984, 109, 573.
48. B. Welz and M. Melcher, Analyst, 1984, 109, 577.
49. R. M. Brown, R. C. Fry, J. L. Moyers, S. J. Northway, M. B. Denton and G. S. Wilson, Anal. Chem., 1981, 53, 1560.
50. M. Yamamoto, Y. Yamamoto and T. Yamashige, Analyst, 1984, 109, 1461.
51. R. Bye, Talanta, 1986, 33, 705.
52. H. I. Schlesinger, H. C. Brown, A. E. Finholt, J. R. Gilbreath, H. R. Hoekstra and E. K. Hyde, J. Am. Chem. Soc., 1953, 75, 215.
53. C. M. Tseng, A. de Diego, D. Amouroux and O. F. X. Donard, J. Anal. At. Spectrom., submitted for publication.