Certification of different mass fractions of DP915635 in maize seed powder : ERM-BF447a, ERM-BF447b, ERM-BF447c, ERM-BF447d and ERM-BF447e

ERM-BF447a-e are five maize seed powder materials certified for their mass fraction of maize event DP915635, (unique identifier code DP-915635-4) produced within the scope of accreditation to ISO 17034:2016 [1]. Genetically modified (GM) maize seeds of the DP915635 event and seeds from a non-GM maize variety were processed to GM and non-GM seed powders of 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 powder, which were sealed under an atmosphere of argon. The minimum sample size for one measurement is 200 mg. Between-unit homogeneity, stability during transport and storage were assessed in accordance with ISO Guide 35:2017 [2]. The certified values were obtained from the gravimetric preparations, taking into account the genetic purity of the non-GM and GM maize powders with respect to the DP915635 maize event and their water mass fractions. The certified values were confirmed by event-specific quantitative polymerase chain reaction, measured within the scope of accreditation to ISO/IEC 17025:2017 [3]. Uncertainties of the certified values were calculated in accordance with ISO 17034:2016 [1] and ISO Guide 35:2017 [2] and include uncertainties related to possible inhomogeneity, instability and characterisation. The materials are intended for the calibration, quality control and assessment of method performance of the event-specific qPCR method for DP915635 maize. Before release of the CRMs, the certification project was subjected to peer-review involving internal experts.