The certification of different mass fractions of VCO-Ø1981-5 in maize seed powder : certified reference materials ERM®-BF438a, ERM®-BF438b, ERM®-BF438c, ERM®-BF438d and ERM®-BF438e

This report describes the production of a set of Certified Reference Materials (CRMs) ERM BF438a, b, c, d and e, which are certified for their VCOØ1981- 5 mass fractions. These materials were produced following ISO Guide 34:2009 and are certified in accordance with ISO Guide 35:2006. Genetically modified (GM) seeds of the maize event VCO-Ø1981-5 and seeds from a non-GM maize variety were milled to obtain GM and non-GM seed powders with a similar particle size distribution. Mixtures of non-GM and GM maize powder were prepared gravimetrically. The certified value was obtained from the gravimetric preparations, taking into account the genetic purity with respect to the event VCO-Ø1981-5 of the two powder materials and their water mass fractions. 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) [4] 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 VCO-Ø1981-5 maize and/or 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 maize seed powder, which were sealed under atmosphere of argon. The minimum amount of sample of the mixtures to be used and recommend for the blank and pure VCO-Ø1981-5 materials is 200 mg. The CRMs were accepted as European Reference Material (ERM®) after peer evaluation by the partners of the European Reference Materials consortium