JRC scientists have elaborated a new measurement system to correctly report genetically modified (GM) content in food and feed products originating from or containing genetically modified organisms (GMO).
The concept of linking a measurement result to a particular reference material and a well-defined reference method should improve the comparability of results.
For all genetic modifications that are authorized in the EU, certified reference materials (CRM) and validated methods based on a polymerase chain reaction (PCR) are available which should allow the correct labelling of products containing GMO.
However, occasional discrepancies among measurement results have been noticed when testing the proficiency of control laboratories. Root cause analyses have shown that wrong quantification results were reported either because inappropriate calibrants were used or because results expressed as DNA copy number ratio were incorrectly converted into a mass fraction.
The European Commission's Joint Research Centre (JRC) hosts the European Union Reference Laboratory for Genetically Modified Food and Feed (EURL-GMFF) and coordinates the European Network for GMO Laboratories.
JRC scientists outlined the requirements to obtain comparable measurement results which are fit for regulatory decision making, in order to further advance GMO controls.
For this, they introducded the concept of a reference measurement system that enables GMO analysis laboratories to relate their results to a universally accessible reference. This establishes metrological traceability to a unique reference point.
The reference measuring system is composed of 3 elements:
- one quantitative (q)PCR reference method per GM event (following ISO/IEC 17025),
- one CRM per GM event (produced according to ISO/IEC 17034, for instance by the JRC)
- one conversion factor (CF) per CRM, which is always anchored to a specified CRM and is required for transforming data from one measurement unit into the other.
With this approach, GM results expressed as DNA copy number ratio can now be converted into mass fraction using such CFs.
The converted results are traceable to the specified CRMs that play a central role in the reference system.
Control laboratories will have the choice between two options:
- quantifying the GM content by qPCR with a well-defined CRM used as calibrator or
- using a digital (d)PCR method.
In the latter case, the dPCR results can be converted into mass fraction with the defined CF and its associated uncertainty.
Read more in: P. Corbisier and H. Emons: Towards metrologically traceable and comparable results in GM quantification. Analytical and Bioanalytical Chemistry 411 (2019) 7-11.
- 5 mars 2019