转基因玉米NK603基体标准物质研制

Development of genetically modified maize(Zea mays L.)NK603 matrix refer-ence materials

转基因安全管理和标识制度的实施需要标准化的检测方法和转基因检测标准物质,转基因标准物质是获得准确、可靠、可比检测结果的保证。目前,转基因玉米NK603已在我国批准进口用作加工原料,其安全监管亟须制备标准物质。本研究将筛选后的转基因玉米NK603杂合种子和对应的非转基因受体种子,按转基因质量分数为60.0 mg g^(–1)、100.0 mg g^(–1)、1000 mg g^(–1)(理论值)的比例配置了3个梯度浓度水平的转基因基体标准物质。利用二重微滴数字聚合酶链式反应(droplet digital polymerase chain reaction,ddPCR)对研制的标准物质进行均匀性与稳定性检测。结果表明:研制的标准物质均匀性良好,可在60℃下运输14 d,稳定性不低于6个月。同时,由8家实验室采用二重ddPCR方法联合测定标准物质NK603转化体与内标基因的拷贝数比值,其标准值及不确定度为:(2.75±0.26)%、(4.68±0.39)%、(51.8±3.7)%。本批标物使用时最小取样量100 mg。可用于转基因食品和饲料中转基因成分NK603的定性和定量检测以及转基因玉米特异性检测方法的评价和实验室质量控制等领域。

The implementation of genetically modified organisms(GMO)safety management and labeling system requires standardized testing methods and reference materials(RMs).Furthermore,the RMs are the guarantee of obtaining accurate,reliable and comparable testing results.At present,genetically modified(GM)maize(Zea mays L.)NK603 has been approved to be imported as processing raw material in China,and its safety supervision urgently needs to prepare RMs.In this study,the heterozygous seeds of GM maize NK603 and the non-GM maize counterpart after identification were well milled and then gravimetrically mixed to prepare three levels of powder RMs according to the mass fractions of 60.0,100.0,and 1000 mg g^(–1).The homogeneity and stability test by duplex ddPCR method showed that the RMs of GM maize NK603 were homogenous and stable for not less than six months.The property values were collaboratively characterized by eight laboratories using duplex ddPCR method.The certified values together with their expanded uncertainties were(2.75±0.26)%,(4.68±0.39)%,and(51.8±3.7)%,respectively.The minimum sample intake was determined to be 100 mg.This batch of RMs can be used for the qualitative and quantitative detection of NK603 event in food and feed,as well as for the evaluation of GM maize NK603-specific assays and laboratory quality control.