Accreditation and Quality Assurance

, Volume 3, Issue 5, pp 185–188

The optimal amount of isotopic spike solution for ultratrace analysis by isotope dilution mass spectrometry

Authors

  • R. Hoelzl
    • Wacker Siltronic AG, D-84479 Burghausen, Germany Tel.: +49-8677-83 7293 Fax: +49-8677-83 3083 e-mail: robert.hoelzl@wacker.de
  • Christian Hoelzl
    • Institute of Physical Chemistry, University of Regensburg, D-93040 Regensburg, Germany
  • Ludwig Kotz
    • Wacker Siltronic AG, D-84479 Burghausen, Germany Tel.: +49-8677-83 7293 Fax: +49-8677-83 3083 e-mail: robert.hoelzl@wacker.de
  • Lazlo Fabry
    • Wacker Siltronic AG, D-84479 Burghausen, Germany Tel.: +49-8677-83 7293 Fax: +49-8677-83 3083 e-mail: robert.hoelzl@wacker.de
SHORT CONTRIBUTION

DOI: 10.1007/s007690050219

Cite this article as:
Hoelzl, R., Hoelzl, C., Kotz, L. et al. Accred Qual Assur (1998) 3: 185. doi:10.1007/s007690050219

Abstract

 Inductively coupled plasma mass spectrometry (ICP-MS) and high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) are powerful methods of determining metallic impurities in the low- and sub-ppt level in process media such as ultra-pure water used in semiconductor and wafer manufacturing. By using mass spectrometers for analysis, an isotope dilution analysis (IDMS) is possible. The reproducibility of an IDMS is unmatched. For concentration levels near the instrument detection limit a novel method is reported to find the optimal amount of isotopic spike solution. This optimal value can be derived by the law of propagation of uncertainty combined with the Poisson statistics of the measured number of counts. Generally, an excess of isotopic spike solution should be used to provide results of lowest possible uncertainty. The results are presented in a diagram for easy practical use.

Key words Isotope dilutionMass spectrometryUltratrace analysisCalibrationUltra-pure water

Copyright information

© Springer-Verlag Berlin Heidelberg 1998