The quantification of genetically modified organisms (GMOs) in food and feed is commonly carried out by event-specific quantitative real-time PCR (qPCR) requiring the use of certified reference materials (CRMs) for the calibration of the qPCR step. Those same CRMs can also be included in the measurement process as quality control samples. The CRMs ERM-BF415e, ERM-BF427c and ERM-BF425c are mixtures of dried conventional and genetically modified maize NK603, maize 98140 and soya 356043 seed powders, respectively. Based on a gravimetric approach, they were prepared and certified for their GMO content expressed as a mass fraction. In a later certification campaign, which required the establishment of analytical quality criteria for the quantification of GMOs described here, they were certified additionally for their genetically modified (GM)-DNA copy numbers in relation to target taxon-specific DNA copy numbers calculated in terms of haploid genomes (DNA copy number ratio). For the three certification campaigns of ERM-BF415e, ERM-BF427c and ERM-BF425c in which the GMO content was measured as DNA copy number ratio, interlaboratory comparisons were run with a large number of expert laboratories. Quality criteria for the evaluation and scrutiny of qPCR raw data were established, such as cut-off limits for the coefficient of determination (R2), PCR efficiency and reproducibility. In this manuscript, different data evaluation approaches for qPCR raw data from the three interlaboratory comparisons were compared and the impact on the mean DNA copy number ratio and its standard deviation has been assessed. The importance of raw data evaluation and data filtering is discussed and its relevance not only for GMO reference material certification campaigns but also for routine GMO measurements is shown.

MEYER Wibke;  CAPRIOARA-BUDA Mihaela;  JEYNOV Boyan;  CORBISIER Philippe;  TRAPMANN Stefanie;  EMONS Hendrik; 

2012-10-15

SPRINGER

JRC70967

1438-2377,   

http://link.springer.com/article/10.1007/s00217-012-1787-7,    https://publications.jrc.ec.europa.eu/repository/handle/JRC70967,   

10.1007/s00217-012-1787-7,