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Detection methods and sampling for the official control of genetically modified organisms

Genetic modifications are most easily and reliably detected at the DNA level. DNA is relatively stable and is often still present in many products, even after processing of the plant material. Therefore, most analysis methods for detection of genetic modifications are based on DNA analysis by means of the polymerase chain reaction (PCR).

Detection methods

Detection methods used in official tests must be standardized in order to ensure that the test results of different laboratories do not differ. Producers and ultimately also consumers are interested that standardized test methods are applied and that analysis results are comparable and reproducible. Standardization is accomplished at the national, EU-wide and worldwide level.

At the European level, for genetically modified food or feed approved in the EU, detection methods are validated by the EU Reference Laboratory (EU-RL) in cooperation with the European Network of GMO laboratories (ENGL) and suitable reference material must be made available. These methods have to be used also for the analyses in Germany.

In order to guarantee a uniform national standard for analyses within the framework of the German food and feed law (§ 64 LFGB) and the Genetic Engineering Act (§ 28b GenTG), the BVL publishes an official methods collection of suitable procedures for sampling and detection of GMOs.

Detection methods for genetically modified (GM) plants that are not authorized in the EU, but are being tested in deliberate releases (field trials) or already cultivated in other countries, represent a particular challenge for the control laboratories, since sufficient information about the genetic modification must be available for their identification.

In addition, there is the problem of whether suitable control samples (reference material) are available. However, non-authorized GM plants are generally detected by so-called screening procedures used to analyze samples. Thus German expert bodies concentrate especially on the further development of these analyses strategies. An additional important instrument here are databases containing detailed information on GMOs known worldwide.

Genetic modifications are most easily and reliably detected at the DNA level. DNA is relatively stable and is often still present in many products, even after processing of the plant material. However, this does not apply to oil or sugars, which no longer contain any DNA. Here, the Regulation (EG) No. 1830/2003 demands traceability of the product through every phase of marketing, i.e. over the entire production and processing chain. This is assured, for example, by accompanying product documents.

Reference material

Reference materials are essential for developing and carrying out detection procedures. Reference materials are the key to ensuring the reliability and accuracy of analysis and measurement results. Appropriate reference materials must be made available for genetically modified food and feed that are authorized according to Regulation (EC) No. 1829/2003, or that are presently going through the authorization process. The composition of these reference materials is precisely defined in Appendix II of Regulation (EG) No. 641/2004.

For GMOs intended for contained use or deliberate release in field trials at defined locations and with time frames, there is no official regulation or obligation to provide reference material.

Reference materials for genetically modified plants not authorized in the EU are generally not available, or only to a limited extent. Countries involved in cases of marketing of GMOs not authorized in the EU are immediately asked by the European Commission to provide detection procedures and reference material for the respective GMO.


An important component of monitoring is the analysis of test samples. For this purpose, a sample must be obtained from the material to be examined, for example a maize consignment. Taking samples for the subsequent official analysis is carried out by so-called official sampler on behalf of the inspection agency of the Federal States. For this application and depending on the goods different sampling guidelines. This should ensure the representative sampling.

For example, from a 20 tons maize consignment a sample of at least about 2.5 kg of maize kernels is collected and submitted to the laboratory for analysis (laboratory sample). For testing of the GMO content a smaller test sample is taken from this maize sample and ground well. From a portion of the flour the genetic material is subsequently isolated (DNA extraction) and used for the final analysis.

Before samples are analyzed for GMOs in control laboratories, spot samples are taken according to a defined procedure (sampling strategies). Increments can be combined to bulk samples or divided appropriately. The purpose is to generate samples that are as reproducible and representative as possible.

Depending on the application, there are recommended sampling strategies for the analysis of GMOs in Germany. Official personnel commissioned by the control authorities of the German Federal States collect samples according to these strategies during inspection of concerned institutions.

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