Detection and quantification of genetically modified organisms (GMOs) in food and feed are essential for regulatory compliance, labeling enforcement, and traceability requirements. Analytical methods must be able to detect low levels of GM material, differentiate between authorized and unauthorized events, and provide accurate quantification. The complexity of the food matrix, processing-induced DNA degradation, and the diversity of GM events pose significant analytical challenges. Method validation through inter-laboratory studies is required for regulatory acceptance.

DNA-based methods are the most widely used approach for GMO detection. Conventional PCR targets specific DNA sequences unique to the GM event and provides qualitative presence or absence results. Real-time PCR (qPCR) using fluorescent probes enables accurate quantification by measuring amplification in real time against standard curves. Digital PCR (dPCR) provides absolute quantification without the need for standard curves by partitioning the sample into thousands of individual reactions. Loop-mediated isothermal amplification (LAMP) offers rapid, field-deployable detection without requiring thermal cycling equipment.

Protein-based methods detect the novel proteins expressed by GM events. Enzyme-linked immunosorbent assay (ELISA) provides quantitative results in a laboratory setting using antibodies specific to the transgenic protein. Lateral flow strips (immunostrips) offer rapid, on-site qualitative screening and are widely used for grain inspection at receiving points and during commodity transport. These methods are most effective for raw agricultural commodities where the target protein is intact, but sensitivity decreases significantly in highly processed foods where proteins are denatured or degraded.

Reference materials are critical for method validation and quantification. Certified reference materials (CRMs) with certified GM concentrations are produced by institutes such as the Institute for Reference Materials and Measurements (IRMM) in the EU. These are used to calibrate analytical methods, verify measurement accuracy, and establish limits of detection (LOD) and quantification (LOQ). Detection strategies include screening for common genetic elements (e.g., CaMV 35S promoter, NOS terminator), construct-specific detection targeting the junction between elements, and event-specific detection targeting the unique plant-DNA junction at the integration site. GMO detection is essential for compliance with labeling and regulation. Methods support the safety assessment by confirming the presence or absence of specific genetic modifications in GM foods.