The certification of different mass fractions of MIR162 in maize seed powder: ERM-BF446a, ERM-BF446b, ERM-BF446c, ERM-BF446d and ERM-BF446e

This report describes the production of ERM®-BF446, composed of five maize seed powder materials certified for their mass fraction of MIR162 (unique identifier SYN-IR162-4). These materials were produced and certified in accordance with ISO 17034:2016 and ISO Guide 35:2017. ERM BF446 was produced within the scope of ISO 17034:2016 accreditation. Genetically modified (GM) maize seeds of the MIR162 event 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 seed powder were prepared gravimetrically. The certified reference materials (CRMs) are available in glass vials containing at least 1 g of dried maize seed powder, which were sealed under an atmosphere of argon. Between-unit homogeneity was quantified and stability during dispatch and storage was assessed in accordance with ISO Guide 35:2017. The minimum sample size for one measurement is 200 mg. The certified value was obtained from the gravimetric preparations, taking into account the genetic purity of the base materials with respect to the MIR162 maize and their water mass fractions. The certified values were confirmed by event-specific quantitative polymerase chain reaction (qPCR) (measurements performed adhering to ISO/IEC 17025:2017). Uncertainties of the certified values were calculated in accordance with ISO 17034:2016 and ISO Guide 35:2017and include uncertainties related to possible inhomogeneity, instability and characterisation. The materials are to be used only for the calibration or quality control for MIR162 maize detection methods. As with any reference material, they can be used for establishing control charts or validation studies. Before release of the CRMs, the certification project was subjected to internal peer-review.