We are doing science for policy
The Joint Research Centre (JRC) is the European Commission's science and knowledge service which employs scientists to carry out research in order to provide independent scientific advice and support to EU policy.
The appropriate standard for the production of reference materials is ISO Gu
The GMO CRMs are gravimetric mixtures of pure GM and non-GM powders certifie
The GMO CRMs can be used as positive controls for the certified GM event for instance to validate a screening method. However, the GMO CRMs should not be used as negative controls for any other GM event than the one certified. Also the blank material of each series is certified to contain less than the certified amount for a given GM event and the absence of this event can not be guaranteed.
For additional information IRMM has conducted a study to verify the GM composition of 33 raw materials used for the production of the GMO CRMs. Those raw materials have been tested by quantitative PCR for the presence/absence of 39 single GM targets known for 7 plant species. It needs to be noted that adventitious presence of other GM events is likely to be heterogeneously distributed over the batch of raw material and needs to be taken into account when comparing the results obtained so far. These results are summarised in the FAQ GMO_attachment.pdf and provide an indication about possible adventitious presence.
IRMM only produces for selected GMO events a pure certified GMO reference ma
GMO reference materials from IRMM can be used as calibrants for DNA-based an
Producers of reference materials guarantee within a specified time (=shelf l
Event-specific detection methods submitted under the provision of Art.
The underlying principle is that one has to check whether the difference bet
For example: Certified reference material BCR-605 (road dust) with a trimethyllead-content of 7.9 ± 1.2 µg/kg has been used. The analytical result was 11.10 µg/kg and the standard measurement uncertainty as determined in the method validation (um) is 15 %, i.e. 1.67 µg/kg. The difference between analytical result and certified value is therefore 3.2 µg/kg. Prior to the determination of the combined uncertainty, the standard uncertainty of the certified value of the reference material must be determined. The uncertainty of the certified value (UCRM) is given as 95 % confidence interval with 6 degrees of freedom as stated on the certificate. The factor of the t-distribution (t95, 6) is 2.447. The confidence interval must be divided by this factor to obtain the standard uncertainty of the certified value. This standard uncertainty (uCRM) is therefore:
The combined uncertainty (uc) of measurement and certified value is the square root of the quadratic sum of the individual uncertainties:
The results show that the uncertainty of the certified value has almost no influence on the combined uncertainty. This combined uncertainty is now multiplied with a coverage factor of 2 to obtain the expanded uncertainty (here 3.48 µg/kg). This expanded uncertainty is bigger than the difference between analytical results and certified values (3.2 µg/kg). Within the limits of the uncertainties, no method bias is visible.
There are two CRM properties that describe the usefulness of a material for
Therefore, one should check whether the certified value of a CRM is traceable to the same reference as one’s method. If this is not the case, the material is unsuitable.
Example: Certified values for dietary fibre traceable to a certain ISO method are only valid, if exactly this method is used.
Additionally, one should check whether commutability is ensured. If this is not the case, the material may be unsuitable.