The certification of reference materials of cotton seed powder with different mass fractions of the cotton event 281-24-236 x 3006-210-23 : certified reference materials ERM -BF422 : ERM-BF422a, ERM-BF422b, ERM-BF422c, ERM-BF422d

This report describes the processing and certification of cotton seed powder Certified Reference Materials (CRMs) with different mass fractions of genetically modified (GM) 281-24-236 x 3006-210-23 cotton seed powder (CRMs ERM®-BF422a, ERM®-BF422b, ERM®-BF422c and ERM®-BF422d). The CRMs were processed in 2005 and certified in 2006 by the European Commission, Directorate General Joint Research Centre, the Institute for Reference Materials and Measurements (IRMM), Geel, Belgium. Non-modified cotton seeds and 281-24-236 x 3006-210-23 cotton seeds, supplied by Dow AgroSciences LLC (Indianapolis, IN, USA) were ground in a vibrating cryogenic mill at low temperature achieved by liquid nitrogen. The mixtures, containing different mass fractions of GM cotton, were gravimetrically prepared by dry-mixing of the powders. The CRMs are intended to be used for the quality control or calibration of methods for the quantification of the 281-24-236 x 3006-210-23 cotton mass fraction in food and feed. The 281-24-236 x 3006-210-23 mass fractions of ERM-BF422 were verified with the help of an event specific real-time polymerase chain reaction (rt-PCR) method. The CRMs are available in glass bottles containing 1 g of cotton seed powder closed under argon atmosphere.