The certification of different mass fractions of DAS-81910-7 in cotton powder : certified reference materials ERM-BF440a, ERM-BF440b, ERM-BF440c, ERM-BF440d and ERM-BF440e certification report

This report describes the production of a set of Certified Reference Materials (CRMs), ERM-BF440a, b, c, d and e, which are certified for their DAS-81910- 7 cotton (unique identifier DAS-8191Ø-7) event mass fractions. These materials were produced following ISO Guide 34:2009 and are certified in accordance with ISO Guide 35:2006. Genetically modified (GM) cotton seeds of the DAS-81910-7 event and seeds from a non GM cotton variety were milled to obtain GM and non-GM seed powders with a similar particle size distribution. Mixtures of non-GM and GM cotton seed powder were prepared gravimetrically. The certified values were obtained from the gravimetric preparations, taking into account the water mass fractions of the two powder materials and the genetic purity with respect to the DAS-81910-7 cotton. The certified values were confirmed by event-specific real-time PCR as an independent verification method (measurements were within the scope of accreditation to ISO/IEC 17025:2005). The uncertainties of the certified values were estimated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) and include uncertainties relating to possible inhomogeneity (Section 4), instability (Section 5) and characterisation (Section 6). The materials are intended for the calibration or quality control of real-time PCR measurements to identify DAS-81910-7 cotton and quantify its mass fraction. As with any reference material, they can also be used for establishing control charts or for carrying out validation studies. The CRMs are available in glass bottles containing at least 1 g of dried cotton seed powder, sealed under an atmosphere of argon. The minimum amount of sample to be used for extraction of the DNA is 200 mg.