Development of genetically modified maize MIR604 matrix reference materials

The safety supervision of genetically modified organisms (GMO) is the guarantee for the healthy development of the biotechnology, and the reference materials (RM) are the material basis for GMOs detection. The lack of RMs makes it difficult to ensure the accuracy, reliability and comparability of the test data. GM maize MIR604 is approved for import as a raw material in China. The safety supervision of GM maize MIR604 urgently requires to prepare RMs. The pure GM maize MIR604 matrix RMs were prepared through the steps of raw material identification, grinding, sieving and water content determination. The results of homogeneity test and stability test showed that the RMs in this batch had good homogeneity within the bottle and between the bottles, the property value of the RMs was stable, allowing them to be transported at room temperature for one month, as even for six months verified by the long-term stability test. The copy number ratio of the transgenic DNA to the total DNA was collaboratively characterized by nine laboratories using the duplex digital PCR of MIR604/ Adh1 . The certified value was 0.50. The various uncertainty components of the RM characterization results were fully evaluated, and the expanded uncertainty was combined to be 0.06 (copy/copy). The specification of RMs of this batch is 1 g bottle–1 and the minimum sample size is 100 mg. This batch of RMs can be used in the fields of safety supervision and labelling of MIR604, and laboratory quality control.