Determination of long-lived radionuclides by inductively coupled plasma quadrupole mass spectrometry using different nebulizers

Abstract

Different nebulizers (cross-flow, ultrasonic and two microconcentric nebulizers) were used for sample introduction of radioactive solutions into a quadrupole-based inductively coupled plasma mass spectrometer (ICP-QMS). The best sensitivity (from 420 to 850 MHz, which is about one order of magnitude higher in comparison with the cross-flow nebulizer) for long-lived radionuclides (²²⁶Ra, ²³⁰Th, ²³⁷Np, ²³⁸U and ²⁴¹Am) was observed using the ultrasonic nebulizer. However, using the ultrasonic nebulizer, a significantly higher sample size (26-fold) in comparison with the micronebulizers is required. Sample introduction by micronebulization with a small sample size in the low picogram range is the method of choice for the determination of long-lived radionuclides. The precision of determination of a 10 ng l^–1 concentration was in the low-% range (and sub-% range) for all measurements using different nebulizer types. The detection limits for the determination of long-lived radionuclides in aqueous solutions applying the different nebulizers were 0.01-0.6 ng l^–1. The flow injection analysis approach was optimized for isotope dilution analysis of ²³²Th (using 20 µl of 5 µg l^–1230Th) by ICP-QMS. The isotopic abundance ratios of ²³⁰Th-²³²Th isotope mixtures (²³⁰Th/²³²Th=0.01, 0.001 and 0.0001) were determined using a microconcentric nebulizer and 1 µg l^–1 Th solutions with a relative external standard deviation of long-term stability measurements (over 20 h) of 0.17, 0.62 and 2.66%, respectively.

References

1. C. K. Kim, R. Seki, S. Morita, S. Yamasaki, T. Tsumura, Y. Igarashi and M. Yamamoto, J. Anal. At. Spectrom., 1991, 6, 205.
2. G. P. Russ and J. M. Bazan, Spectrochim. Acta, Part B, 1987, 42, 49.
3. J. S. Becker and H.-J. Dietze, Adv. Mass Spectrom., 1998, 14, 681.
4. J. S. Crain, Spectroscopy, 1996, 11, 30.
5. J. S. Becker and H.-J. Dietze, J. Anal. At. Spectrom., 1997, 12, 881.
6. P. D. P. Taylor, P. De Bievre, A. J. Walder and A. Entwistle, J. Anal. At. Spectrom., 1995, 10, 395.
7. I. T. Platzner, J. S. Becker and H.-J. Dietze, At. Spectrosc., 1999, 20, 6.
8. W. Kerl, J. S. Becker, H.-J. Dietze and W. Dannecker, Fresenius' J. Anal. Chem., 1997, 359, 40.
9. Inductively Coupled Plasma Mass Spectrometry, ed. A. Montaser, Wiley-VCH, New York, Chichester, Weinheim, 1998.
10. J. S. Becker and H.-J. Dietze, J. Anal. At. Spectrom., 1998, 13, 1057.
11. W. Kerl, J. S. Becker, H.-J. Dietze and W. Dannecker, Adv. Mass Spectrom., 1998, 14, MoPo143.
12. K. Hoppstock, J. S. Becker and H.-J. Dietze, At. Spectrosc., 1997, 18, 180.
13. W. Kerl, J. S. Becker, H.-J. Dietze and W. Dannecker, J. Anal. At. Spectrom., 1996, 11, 723.
14. J. I. G. Alonso, F. Sena, P. Arbore, M. Betti and L. Koch, J. Anal. At. Spectrom., 1991, 6, 335.
15. J. M. B. Moreno, J. I. G. Alonso, P. Arbore, G. Nicolaou and L. Koch, J. Anal. At. Spectrom., 1996, 11, 929.
16. J. S. Becker, G. Küppers, F. Carsughi, W. Kerl, W. Schaal, F. Ullmaier and H.-J. Dietze, Ber. Forschungszentrums Jülich, 1996, 3272, 143.
17. W. Kerl, J. S. Becker, W. Dannecker and H.-J. Dietze, Fresenius' J. Anal. Chem., 1998, 362, 433.
18. K. L. Sutton, C. B'Hymer and J. A. Caruso, J. Anal. At. Spectrom., 1998, 13, 885.
19. A. Beauchemin and A. A. Specht, Anal. Chem., 1997, 69, 3183.
20. K. G. Heumann, Int. J. Mass Spectrom. Ion Processes, 1992, 118/119, 575.
21. IUPAC, Pure Appl. Chem., 1991, 63, 991.
22. J. S. Becker and H.-J. Dietze, presented at the 4th Symposium Massenspektrometrische Verfahren der Elementspurenanalyse, Mainz, 1998, Fresenius' J. Anal. Chem., in the press.