Overview
ISO 21570:2005 - "Foodstuffs - Methods of analysis for the detection of genetically modified organisms and derived products - Quantitative nucleic acid based methods" - provides a harmonized framework for quantitative detection of GMOs using PCR. The standard defines general requirements for specific amplification, detection, confirmation and quantitation of DNA target sequences so that accurate, comparable and reproducible results can be obtained across different laboratories. Although developed for food matrices, ISO 21570:2005 also applies to feed and environmental plant samples.
Key topics and technical requirements
- Quantitative PCR approaches: Accepts competitive and real‑time PCR formats; in real‑time PCR amplification, detection and confirmation occur simultaneously.
- Target definition: Methods specify which DNA target sequences to quantify (GMO element vs endogenous taxon‑specific reference).
- Calibration and traceability: Calibrants should be traceable to certified reference materials (CRMs) where available. The standard gives guidance on calibration design (e.g., multiple calibration points with replicates) to control measurement uncertainty.
- Dynamic range and LOQ: DNA concentrations must lie within the method’s dynamic range; determination of the limit of quantitation (LOQ) follows ISO 24276 guidance.
- Controls and quality assurance: Analysis requires appropriate positive/negative and inhibition controls, duplicate testing of extracts and adherence to laboratory quality systems.
- Reagents and equipment: Use molecular biology grade reagents or those specified by the method; annexes list apparatus and reagents for example methods.
- Target stability and biological considerations: Consider allelic/copy number stability across cultivars and the impact of stacked genes on quantitative interpretation.
- Annexed example methods: Informative annexes (A–D) present worked examples - target taxon‑specific, screening, construct‑specific and event‑specific real‑time PCR methods (e.g., methods for maize and soybean events).
Applications and users
ISO 21570:2005 is intended for:
- Food and feed testing laboratories performing GMO quantitation
- National reference and regulatory laboratories validating compliance with labeling thresholds
- Biotechnology and food companies doing product testing and quality control
- Research and environmental monitoring groups detecting GMO presence in plant samples
Practical applications include routine compliance testing, surveillance of imported/processed foods, method validation, and inter‑laboratory comparability studies.
Related standards
- ISO 21569:2005 - qualitative nucleic acid methods for GMO detection
- ISO 21571 - nucleic acid extraction methods
- ISO 24276 - general requirements, LOQ and definitions
- ISO Guide 32 - calibration and use of reference materials
Keywords: ISO 21570:2005, GMO detection, quantitative PCR, real‑time PCR, food analysis, certified reference materials, calibration, limit of quantitation, PCR quantitation.
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