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We were regularly asked to provide information about the LOD (limit of detection) for the detection of ingredients that might derive from GMO (genetically modified organisms) in complex food (and feed) preparations. For scientific reasons this is impossible.

A complex product e.g. a piece of pizza might contain different potential plant materials derived from e.g. soy, corn, canola in an unknown composition and degree of processing. We are screening for typical “events” (DNA signal sequences), that are not specific to a single GMO plant, but are commonly used for genetic modification as start and stop sequences (e.g. 35s, t-nos etc.) for modified DNA inserts, encoding specific new properties for example a pesticide resistance.

In a complex food / feed these marker sequences can derive from one or even numerous different GMOs.

Therefore a LOD for DNA marker events can only be given for unprocessed or low-processed materials from plant species e.g. soy beans. In such a case we can state that the LOD will be 0,05% GMO-DNA with respect the known content of total soy in the sample.

In a complex product a LOD would be expected to be at best 0,05% ,but can also be higher, for the reason outlined.

We can only state a presence / absence of the marker events in a complex product. A “positive” sample however gives a clear indication of the presence of GMO marker sequences screened in this sample.
In case of a positive finding, it needs to be tracked back to the raw material batches that were used, to give an indication about the potential source of GMO contamination. The further investigation includes supplementary raw material screenings. Positive screening results can be followed by identification of the responsible GMO species and finally after identification when calibration standards are commercially available, even a quantification of the identified GMO might be possible. It should be mentioned that this further investigation is related to additional cost.

Last but not least we like to note, that we are talking here about a general limitation of GMO analysis in complexly composed matrices, which is not lab-specific or method-specific restriction.

If you have further questions please do not hesitate to contact our specialists!