Inter-laboratory validation by event-specific qPCR methods for the detection of genetically modified insect and herbicide-tolerant maize DBN9501

DBN9501 is a new maize transgenic event characterised by being resistance to insects and herbicides. To meet genetically modified (GM)-labeling requirements and monitor the unintended release of genetically modified organisms (GMOs), developing a creditable and applicable method for identifying and quantifying GM events is essential. Herein we developed an event-specific method and validated it through inter-laboratory ring trials using blind samples. The limit of detection (LOD) and limit of quantification (LOQ) of copy number ratio were confirmed at 0.05% and 0.1%, respectively. The quantitative bias ranged from  -3.52 to 10.38%, and the relative standard deviation (RSD) of the method was < 25%. Furthermore, the expanded uncertainty for the blind samples S1 − S5 was 0.22%, 0.10%, 0.05%, 0.03%, and 0.02%. These results demonstrated that the event-specific quantitative PCR method could identify and quantify GM DBN9501 for further routine lab analysis.