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Characterisation of High Purity Metals as Primary Standards for Element Determination

Characterisation of High Purity Metals as Primary Standards for Element Determination. Bundesanstalt für Materialforschung und –prüfung (BAM) H. Kipphardt , M. Czerwensky and R. Matschat.

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Characterisation of High Purity Metals as Primary Standards for Element Determination

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  1. Characterisation of High Purity Metals as Primary Standards for Element Determination Bundesanstalt für Materialforschung und –prüfung (BAM) H. Kipphardt, M. Czerwensky and R. Matschat

  2. … serve as primary standards for chemical measurements (mass or amount of substance of an identified substance) ... used for calibration … to establish SI traceability High purity materials ... Measurement result in field laboratory e.g. copper in tap water traceable commercialcalibration solutions Primary calibration solution e.g. PTB-001 Primary standard e.g. BAM-Y001 (copper) SI

  3. (1) Commercial calibration solutions

  4. Dissolution of high purity metals

  5. ... hardly exist ... usually incompletely characterised using semi-quantitative measurement techniques ... no uncertainty statement Materials certified for purity ...

  6. Target: Primary standards ... ... of high metrological quality ... small uncertainty according to GUM ... serve as national standards for element analysis in Germany (with PTB)

  7. Primary standards of Type A ... ... intended for analyte calibration (i.e. element amount standard) ... certified for the mass fraction of the matrix element in a ‘pure’ material ... for use within the NMIs multiplication to the field via cooperation

  8. Primary standards of type A ... w(E) known to better than 0.01 % ... approach: 100%-Imp ... measurement of all impurity elements (including O, N ...) ... measurement of total impuritiy content (bulk and surface)

  9. LA-ICP MS ET and HG AAS HR ICP MS continuous nebulization check of dissolution step validation additional information consistency check ICP OES, (INAA) FI-ICP MS validation additional information lowering detection limits Gas and Non-metal analysis combined uncertainty (GUM) certified value CGHE; PAA nuclear methods Certification approach

  10. BAM-Y001: overview of impurities w(Cu, BAM-Y001)= 0.999 968  0.000 010 with k=2

  11. mass fraction in mg/kg 100 HR ICP MS ET AAS ICP-OES HE/PAA HE/IR Photometrie INAA 10 1 0,1 0,01 Ag As Bi C Ca Cr Fe N Ni O Pb S Sb Se Si Sn Measurements using different methods

  12. BAM-Y001certificationreport

  13. BAM-Y001Certificate

  14. Element Value Uncertainty Upper limit estimates BAM-Y001 Cu 0,999 970 0,000 010 - BAM-Y002 Fe 0,999 862 0,000 044 P BAM-Y003 Si 0,999 91 0,000 07 H, F, Cl, Br, I BAM-Y004 Pb 0,999 92 0,000 06 H, P, Si, F, Cl, Br, I BAM-Y005 Sn 0,999 91 0,000 06 H, Si, F, Cl, Br, I BAM-Y006 W 0,999 81 0,000 10 H, F, Cl, Br, I BAM-Y007 Bi 0,999 90 0,000 07 H, K, Si, S, F, Cl, Br, I BAM-Y008 Ga 0,999 92 0,000 07 H, Si, F, Cl, Br, I BAM-Y009 NaCl 0,999 84 0,000 09 H, F, K, Si, S BAM-Y010 KCl 0,999 83 0,000 10 H, F, Si, S, Mn, Fe, As Certified materials

  15. Elements under investigation ...

  16. ... intended for matrix investigations (spectrometry) ... certified for very low metallic impurities (typically 1-50 g/kg) Materials of type B

  17. BAM Cu type B: overview of impurities 500 mg/kg oxygen !

  18. primary standards seem to be necessary,- also for analytical chemistry their realisation has been successfullydemonstrated realisation requires a variety of methodsand staying power Conclusion 1

  19. Purity of Nickel with respect to six metallic analytes Quantity of interest:w(Ag)+w(Al)+w(Cu)+w(Fe)+w(Pb)+w(Zn)and interim results; expected range: 0.1 – 5.0 mg/kg Participants: 5 + BAM I, BAM II for homogeneity and IDMS NRC, for IDMS BAM Status: completed CCQM-P62: Background

  20. CCQM-P62: methodsused

  21. CCQM-P62: Additional IDMS experiments Because of the inconsistent results in the pilot study, additionally IDMS was applied as ‘reference’: • IDMS for Al is impossible • NRC: Ag, Pb, Zn • BAM: Pb, Zn, Cu, Fe • IDMS is not used to calculate mean of CCQM-P62

  22. CCQM-P62: overview of IDMS results • Good consistency of results for Pb and Zn. • Some experimental problems with Fe measurements. • w(Ag+Cu+Fe+Pb+Zn) = (3,09 ± 0,12) mg/kg [without Al]

  23. CCQM-P62: results Pb agreement < 30 %

  24. CCQM-P62: results Zn agreement 30 %

  25. CCQM-P62: results Ag well agreement, one exception

  26. CCQM-P62: results Cu problem: factor 5

  27. CCQM-P62: results Fe problem: factor 10

  28. CCQM-P62: results Al problem: > factor 100

  29. CCQM-P62: results total problem: factor 8

  30. CCQM-P62: overview of results

  31. number of participants low=> limited interest (or ability) concluded discrepancies by a factor of 8 for the value of the target quantity, not covered by the corresponding uncertainties discrepancies based on discrepancies for individual impurities Results for a ‘rather simple task’ => worldwide the characterisation of high purity materials is not to be comparable. few clusters of laboratories can be detected 3 laboratories report rather low values IDMS confirms the lower values for Pb, Zn, Ag, Cu, FeGDMS shows very low value for Al=> may be for some labs the blank is not fully under control Conclusion 2: CCQM-P62

  32. END

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