Producing Laboratory: MESL
Oyster (Methyl Mercury)

The certificate for the IAEA-470 CRM is the only official source for the trace elements mass fractions certified values and their expanded uncertainties. 

ElementUnitCertified value aExpanded uncertainty b
Agmg kg-11.290.10
Asmg kg-111.90.9
Camg kg-12.43x1030.28x103
Cdmg kg-13.140.24
CH3Hgmg kg-1 as Hg5.22x10-30.87x10-3
Comg kg-10.2010.025
Crmg kg-10.970.11
Cumg kg-114613
Femg kg-113112
Hgmg kg-121.1x10-32.1x10-3
Mgmg kg-13.08x1030.39x103
Mnmg kg-166.75.3
Namg kg-119.7x1032.3x103
Pbmg kg-10.3610.053
Rbmg kg-15.140.59
Semg kg-13.060.33
Srmg kg-120.61.6
Vmg kg-10.900.13
Znmg kg-172748

(a) Information on calculation of certified values 

Certified values are calculated from the accepted data sets, each set being obtained by a different laboratory and/or a different method of determination following ISO Guide 35 ‘Reference materials – General and statistical principles for certification’. 

(b) Information on method used for uncertainty estimation 

The uncertainty is expressed as a combined uncertainty with a coverage factor k = 2, corresponding to a level of probability 95%, estimated in accordance with the JCGM 100:2008 Evaluation of measurement data – Guide to the expression of uncertainty in measurement’ and ISO Guide 35. 

 The assigned property values were established, considering the results reported by expert laboratories, participating in the characterisation campaign for the IAEA-470. The characterisation campaign was organised by the IAEA Environment Laboratories in Monaco.  The details concerning the production process and all reported results, as well as the criteria for the assignment of property values are presented in the certification report for the IAEA-470.