Two simple interface designs for capillary electrophoresis–inductively coupled plasma mass spectrometry†

Abstract

The design and implementation of two different interfaces for capillary electrophoresis–inductively coupled plasma mass spectrometry (CE–ICP-MS) are described. These interfaces will allow for on-line analysis of CE effluents with ICP-MS detection. One interface is based on a concentric tube nebulizer and the other on a standard cross-flow nebulizer. These systems were investigated in parallel and their performances, under various experimental conditions, were compared. Each interface possesses a unique set of advantages and shortcomings. Recognizing that typical sample flow rates for ICP-MS are of the order of ml min^–1 and that the flow rates for CE are a few nl min^–1, some difficulties in flow compatibility are encountered. Aspects discussed include interface considerations, flow compatibility and the influence of flow rates on the overall sensitivity. Several guidelines are provided for workers interested in implementing a CE–ICP-MS instrument for elemental speciation. The Cd detection limits in rabbit metallothionein were 2.36 and 0.21 µg ml^–1 for the concentric and cross-flow nebulizers, respectively.

References

1. Trace Metal Analysis and Speciation, ed. Krull, I. S., Elsevier, New York, 1991.
2. Metal Speciation and Contamination of Soil, ed. Allen, H. E., Huang, C. P., Bailey, G. W., and Bowers, A. R., Lewis, Chelsea, MI, 1994.
3. Chemical Speciation in the Environment, ed. Ure, A. M., and Davidson, C. M., Blackie, Glasgow, 1995.
4. T. H. Bothwell, R. W. Charlton, J. D. Cook and C. A. Finch, Iron Metabolism in Man, Blackwell, Oxford, 1979.
5. R. Hussain, R. B. Walker, M. Layrisse, P. Clark and C. A. Finch, Am. J. Clin. Nutr., 1965, 16, 464.
6. B. R. Schricker, D. D. Miller and J. R. Stouffer, J. Food Sci., 1982, 47, 740.
7. C. M. M. Smith and J. M. Harnly, J. Anal. At. Spectrom., 1997, 12, 1055.
8. J. D. Latshaw, J. Nutr., 1975, 105, 32.
9. J. D. Latshaw and M. D. Biggert, Poult. Sci., 1981, 60, 1309.
10. R. Lobinski, Appl. Spectrosc., 1997, 51, 260A.
11. E. Bulska, J. Anal. At. Spectrom., 1992, 7, 201.
12. R. Lobinski and F. C. Adams, Trends Anal. Chem., 1993, 12, 41.
13. N. P. Vela, L. K. Olson and J. A. Caruso, Anal. Chem., 1993, 65, 585A.
14. M. A. Quijano, A. M. Gutiérrez, M. C. Pérez-Conde and C. Cámara, J. Anal. At. Spectrom., 1996, 11, 407.
15. K. E. Ødegård and J. W. Lund, Anal. At. Spectrom., 1997, 12, 403.
16. D. R. Baker, Capillary Electrophoresis, Wiley, New York 1995.
17. Inductively Coupled Plasmas in Atomic Spectrometry, ed. Montaser, A., and Golightly, D. W., VCH, New York, 1992.
18. J. W. Olesik, J. A. Kinzer and S. V. Olesik, Anal. Chem., 1997, 67, 1.
19. Q. Lu, S. M. Bird and R. M. Barnes, Anal. Chem., 67, 2949.
20. L. S. Milstein and J. A. Caruso, paper presented at the Pittsburgh Conference on Analytical Chemistry and Applied Spectrometry, Atlanta, GA, March 1997, paper 597.