CIPM MRA COMPARISON REPORTS

nullThe SIM supplementary comparison SIM.QM-S18, for the determination of Cd and Pb in cacao powder, was jointly organized by the National Research Council Canada (NRC) and the Centro Nacional de Metrología (CENAM). The objective was to assess and demonstrate the analytical capabilities of National Metrology Institutes (NMIs) and Designated Institutes (DIs) of SIM members (or other regions) in the accurate determination of trace elements in cacao powder.  This matrix had not previously been tested in CCQM or RMO comparisons and was selected due to its significant relevance to food safety regulations due to the potential presence of elevated levels of toxic metals.
Evidence of successful participation in formal, relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by NMIs and DIs. 
A total of nineteen NMIs and DIs participated in SIM.QM-S18. Participants were requested to determine the mass fractions, in mg/kg, of cadmium and lead in commercially available cacao powder.  A variety of instrumental techniques were employed, including inductively coupled plasma mass spectrometry (ICP-MS), isotope dilution ICP-MS (ID-ICP-MS), inductively coupled plasma optical emission spectrometry (ICP-OES) and graphite furnace atomic absorption spectrometry (GFAAS). The majority of the participants claimed traceability to NIST primary calibrants or their own certified reference materials (CRMs). Several matrix CRMs were used for quality control.
The NIST decision tree was used to assign the supplementary comparison reference value (SCRV) for each measurand and to calculate the degrees of equivalence of each participating NMIs and DIs, following the IAWG Guidance on using NIST Decision Tree for comparison reporting from 30 June 2023.
Successful participation in SIM.QM-S18 demonstrates measurement capability for the determination of elements in food matrices. According to the IAWG Core Capability Matrix, cacao powder falls into the matrix challenge called “High organic content”, and the results of this comparison support broad scope CMC claims for transition elements in high organic content materials.