Problems Encountered During the Development of a Method for the Speciation of Mercury and Methylmercury by High-performance Liquid Chromatography Coupled to Inductively Coupled Plasma Mass Spectrometry

Abstract

A study was carried out to develop a method for the determination of methylmercury and inorganic mercury by coupling HPLC to ICP-MS. During the course of this work it was noted that the use of stainless-steel components in the HPLC system led to adsorption of the mercury compounds, which was more pronounced with mercury(II) chloride than methylmercury. In particular, the use of a stainless steel sample loop led to larger peaks for both compounds, but particularly inorganic mercury, compared with a PEEK loop. The type of loop used had no effect on the separation of these compounds on an ODS column using a mobile phase composed of 10 mM tetrabutylammonium bromide and 60% methanol. However, both of the two ODS stainless-steel columns tested adsorbed the compounds to some degree, leading to a slow bleed of mercury. The use of components made with materials other than stainless steel, e.g., PEEK sample loops and glass-lined columns, and inclusion of a sulfur ligand in the eluent (2-mercaptoethanol) reduced these problems significantly.

References

1. P. J. Craig, in Organometallic Compounds in the Environment, ed. P. J. Craig, Longman, Harlow, 1986, ch. 2.
2. G. Westöö, Acta Chem. Scand., 1966, 20, 2131.
3. K. Noren and G. Westöö, Var Foeda, 1967, 19, 13.
4. N. Imura, S.-K. Pan, M. Shimitzu, T. Ukita and K. Tonamura, Ecotoxicol. Environ. Saf., 1977, 1, 255.
5. S. Rapsomanikis, in Environmental Analysis Using Chromatography Interfaced with Atomic Spectroscopy, ed. Harrison, R. M., and Rapsomanikis, S., Ellis Horwood, Chichester, 1989, ch. 10.
6. S. J. Hill, M. J. Bloxham and P. J. Worsfold, J. Anal. At. Spectrom., 1993, 8, 499.
7. A. Woller, H. Garraud, F. Martin, O. F. X. Donard and P. Fodor, J. Anal. At. Spectrom., 1997, 12, 53.
8. M. K. Behlke, P. C. Uden and M. M. Schantz, Anal. Commun., 1996, 33, 91.
9. M. Heintz, B. Buckley, W. Fang and W. Johnson, paper presented at the 21st Annual FACSS Conference.
10. R. Falter and H. F. Schöler, J. Chromatogr. A, 1994, 675, 253.
11. S. C. K. Shum, H. Pang and R. S. Houk, Anal. Chem., 1992, 64, 2444.
12. I. S. Krull, D. S. Bushee, R. G. Schleicher and S. B. Smith, Jr., Analyst, 1986, 111, 345.
13. Y.-S. Ho and P. C. Uden, J. Chromatogr. A, 1994, 688, 107.
14. C.-W. Huang and S.-J. Jiang, J. Anal. At. Spectrom., 1993, 8, 681.
15. D. S. Bushee, Analyst, 1988, 113, 1167.
16. O. Evans and G. D. McKee, Analyst, 1988, 113, 243.
17. R.-D. Wilken, Fresenius' J. Anal. Chem., 1992, 342, 795.