Steady state acid effects in ICP-MS

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Ian I. Stewart and John W. Olesik


Abstract

The influence of concentrated nitric acid matrices in inductively coupled plasma mass spectrometry (ICP-MS) was investigated. Generally, analyte signal intensities decrease with increasing acid concentration. However, under certain conditions signal enhancements occur. Acid induced changes are highly dependent on the nebulizer gas flow rate and power, in both controlling the analyte and aerosol transport to the plasma and local plasma conditions. The largest decrease in signal occurs when the experimental parameters (power and ion optics settings) were optimized to produce the maximum signal for 2% HNO3 matrices at higher nebulizer gas flow rates and least pronounced when the experimental parameters were optimized at low nebulizer gas flow rates. This is consistent with smaller relative changes in the analyte and aerosol transport rates to the plasma at lower nebulizer gas flow rates as a function of increased acid concentration. Working under robust conditions for ICP-MS not only reduced the magnitude of the acid effect but often resulted in signal enhancements rather than suppressions with increased acid content. Because the acid effect changes the local plasma temperature within the sampling volume, it affects ion kinetic energies and therefore transmission efficiency from the plasma to the MS detector. For a given set of operating conditions, a cooler plasma results from increased acid concentration, which can reduce analyte ionization efficiency, enhance metal-to-oxide ratios and incise the contribution of molecular ions and isobaric overlaps. Acid effects originate in the sample introduction system and so occur independent of the method of detection. Consistent with reports in ICP-OES, the acid effect in ICP-MS can be minimized but not eliminated by switching to more robust conditions. Robust conditions in ICP-MS are generally characterized by a nebulizer gas flow rate less than that required to produce optimum sensitivity, or a low nebulizer gas flow rate and high power.


References

  1. S. Greenfield, H. McD. McGeachin and P. B. Smith, Anal. Chim. Acta, 1976, 84, 67 CrossRef CAS.
  2. R. L. Dahlquist and J. W. Knoll, Appl. Spectrosc., 1978, 32, 1 CAS.
  3. F. J. M. J. Maessen, J. Balke and J. L. M. De Boer, Spectrochim. Acta, Part B, 1982, 37, 517 CrossRef.
  4. H. Ishii and K. Satoh, Talanta, 1983, 30, 111 CrossRef CAS.
  5. M. A. E. Wandt, M. A. B. Pougnet and A. L. Rodgers, Analyst, 1984, 109, 1071 RSC.
  6. A. Delijska and M. Vouchkov, Fresenius' Z. Anal. Chem., 1985, 321, 448 CrossRef.
  7. S. S. Que Hee, T. J. MacDonald and J. R. Boyle, Anal. Chem., 1985, 57, 1242 CrossRef CAS.
  8. R. I. Botto, Spectrochim. Acta, Part B, 1985, 40, 397 CrossRef.
  9. R. M. Belchamber, D. Betteridge, A. P. Wade, A. J. Cruickshank and P. Davidson, Spectrochim. Acta, Part B, 1986, 41, 503 CrossRef.
  10. C. J. Pickford and R. M. Brown, Spectrochim. Acta, Part B, 1986, 41, 183 CrossRef.
  11. J. Farino, J. R. Miller, D. D. Smith and R. F. Browner, Anal. Chem., 1987, 59, 2303 CrossRef CAS.
  12. E. G. Chudinov, I. I. Osroukhova and G. V. Varvanina, Fresenius' Z. Anal. Chem., 1989, 335, 25 CrossRef CAS.
  13. E. Yoshimura, H. Suzuki, S. Yamazaki and S. Toda, Analyst, 1990, 115, 167 RSC.
  14. M. Marichy, M. Mermet and J. M. Mermet, Spectrochim. Acta, Part B, 1990, 45, 1195 CrossRef.
  15. J. C. Ivaldi, J. Vollmer and W. Slavin, Spectrochim. Acta, Part B, 1991, 46, 1063 CrossRef.
  16. A. Fernández, M. Murillo, N. Carrión and J.-M. Mermet, J. Anal. At. Spectrom., 1994, 9, 217 RSC.
  17. A. Canals, V. Hernandis, J. L. Todoli and R. F. Browner, Spectrochim. Acta, Part B, 1995, 50, 305 CrossRef.
  18. M. Carre, K. Lebas, M. Marichy, M. Mermet, E. Poussel and J. M. Mermet, Spectrochim. Acta, Part B, 1995, 50, 271 CrossRef.
  19. I. B. Brenner, J. M. Mermet, I. Segal and G. L. Long, Spectrochim. Acta, Part B, 1995, 50, 323 CrossRef.
  20. I. B. Brenner, I. Segal, M. Mermet and J. M. Mermet, Spectrochim. Acta, Part B, 1995, 50, 333 CrossRef.
  21. B. A. Zarcinas, M. J. McLaughlin and M. K. Smart, Commun. Soil Sci. Plant Anal., 1996, 27, 1331 Search PubMed.
  22. C. Dubuisson, E. Poussel and J.-M. Mermet, J. Anal. At Spectrom., 1997, 12, 281 RSC.
  23. I. I. Stewart and J. W. Olesik, J. Anal. At. Spectrom., 1998, 13, 843 RSC.
  24. S. H. Tan and G. Horlick, Appl. Spectrosc., 1986, 40, 445 CAS.
  25. S. H. Tan and G. Horlick, J. Anal. At. Spectrom., 1987, 2, 745 RSC.
  26. R. S. Houk and J. A. Olivares, Anal. Chem., 1986, 58, 20 CrossRef CAS.
  27. J. J. Thompson and R. S. Houk, Appl. Spectrosc., 1987, 41, 801 CAS.
  28. D. Beauchemin, J. W. McLaren and S. S. Berman, Spectrochim. Acta, Part B, 1987, 42, 467 CrossRef.
  29. D. C. Gregoire, Spectrochim. Acta, Part B, 1987, 42, 895 CrossRef.
  30. H. P. Longerich, J. Anal. At. Spectrom., 1989, 4, 665 RSC.
  31. S. E. Hobbs and J. W. Olesik, Spectrochim. Acta, Part B, 1993, 48, 817 CrossRef.
  32. J. C. Fister, III and J. W. Olesik, Spectrochim. Acta, Part B, 1991, 46, 869 CrossRef.
  33. I. I. Stewart and J. W. Olesik, J. Anal. At. Spectrom., submitted for publication Search PubMed.
  34. J. M. Mermet, J. Anal. At. Spectrom., 1998, 13, 419 RSC.
  35. CRC Handbook of Chemistry and Physics, ed. D. R. Lide, CRC Press, Boca Raton, FL, 1991–92 Search PubMed.
  36. Y. Q. Tang and C. Trassy, Spectrochim. Acta, Part B, 1986, 41, 143 CrossRef.
  37. W. E. Dasent, Inorganic Energetics, Cambridge University Press, Cambridge, 2nd edn., 1982 Search PubMed.
  38. R. C. Hutton and A. N. Eaton, J. Anal. At. Spectrom., 1987, 2, 595 RSC.
  39. G. Zhu and R. F. Browner, J. Anal. At. Spectrom., 1988, 3, 781 RSC.
  40. R. Tsukahara and M. Kubota, Spectrochim. Acta, Part B, 1990, 45, 581 CrossRef.
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