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The aim of this comparison was to demonstrate the capability of national metrology institutes to measure elemental mass fractions at a level of w(E) ≈ 1 g/kg as found in almost all mono-elemental calibration solutions. These calibration solutions represent an important link in traceability systems in inorganic analysis. Virtually all traceable routine measurements are linked to the SI through these calibration solutions. Every participant was provided with three solutions of each of the three selected elements chromium, cobalt and lead. This comparison was a joint activity of the Inorganic Analysis Working Group (IAWG) and the Electrochemical Analysis Working Group (EAWG) of the CCQM and was piloted by the Physikalisch-Technische Bundesanstalt (PTB, Braunschweig, Germany) with the help of the Bundesanstalt für Materialforschung und -prüfung (BAM, Berlin, Germany), the Centro Nacional de Metrología (CENAM, Querétaro, Mexico) and the National Institute of Standards and Technology (NIST, Gaithersburg, USA).
A small majority of participants applied inductively coupled plasma optical emission spectrometry (ICP OES) in combination with a variety of calibration strategies (one-point-calibration, bracketing, calibration curve, each with and without an internal standard). But also IDMS techniques were carried out on quadrupole, high resolution and multicollector ICP-MS machines as well as a TIMS machine. Several participants applied titrimetry. FAAS as well as ICP-MS combined with non-IDMS calibration strategies were used by at least one participant. The key comparison reference values (KCRV) were agreed upon during the IAWG/EAWG meeting in November 2011 held in Sydney as the added element content calculated from the gravimetric sample preparation. Accordingly the degrees of equivalence were calculated. Despite the large variety of methods applied no superior method could be identified. The relative deviation of the median of the participants' results from the gravimetric reference value was equal or smaller than 0.1% (with an average of 0.05%) in the case of all three elements.
The major source of the anthropogenic platinum group element (PGE) emission is attributed to the use of catalytic converters in automobiles. This paper describes the work performed by three National Metrology Institutes (Laboratoire national de métrologie et dessais, by the Physikalisch-technische bundesanstalt, Bundesanatalt für materialforschung und prûfung), in the framework of the Joint Research Project 'PartEmission' under the European Metrology Research Program. An analytical procedure based on a cationic exchange protocol and the isotope dilution or standard addition using an Inductived Coupled Plasma Mass Spectrometer, ICP-MS, for the quantification of the elements Pt, Pd and Rh from automotive exhaust emissions is described. Results obtained on a road dust certified reference (BCR 723) material showed a good agreement with the certified values, at ng/g levels, and relative expanded uncertainties within the range of 7–10%. Analysis of filters impacted with automotive exhaust particle emissions (from a diesel engine) showed the amount of collected PGE at levels of 10–1000 pg/filter. Their quantifications followed the developed analytical protocol that had been carried out with relative expanded uncertainties in the range of a few per cent up to 20% per filter. Nevertheless, a lack of homogeneity between the filters was observed, making the comparison between the project partners difficult in the sake of the validation of their analytical procedures on real samples.