Zhang Kai, Liao Chia-Ding, Prakash Shristi, Conway Michael, Cheng Hwei-Fang
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, 5001 Campus Dr., College Park, MD 20740.
Ministry of Health and Welfare, Taiwan Food and Drug Administration, 161-2 Kunyang St, Nangang District, Taipei, 115-61 Taiwan, People's Republic of China.
J AOAC Int. 2018 May 1;101(3):677-685. doi: 10.5740/jaoacint.17-0341. Epub 2017 Oct 2.
An interlaboratory study was conducted to evaluate stable isotope dilution and LC tandem MS (MS/MS) for the determination of aflatoxins B1, B2, G1, G2, and M1 (AFB1, AFB2, AFG1, AFG2, and AFM1) in milk, milk-based infant formula (formula), and feed. Samples were first fortified with five 13C uniformly labeled aflatoxins {[13C]-internal standard (IS)} corresponding to the five native aflatoxins, which were subsequently extracted with acetonitrile-water (50 + 50, v/v), followed by centrifugation, filtration, and LC-MS/MS analysis. In addition to certified milk powder and animal feed, the three participating laboratories also analyzed milk, formula, and feed fortified with the five aflatoxins at concentrations ranging from 0.5 to 50 ng/g. The majority of recoveries ranged from 80 to 120%, with RSDs < 20%. Method LOQs were determined by the three laboratories using the three sample matrixes in replicates (n = 8), and the determined LOQs of AFB1, AFB2, AFG1, AFG2, and AFM1 ranged from 0.1 to 0.91, 0.24 to 0.64, 0.28 to 1.52, 0.19 to 3.80, and 0.12 to 0.45 ng/g, respectively. For detected aflatoxins in the certified materials, all measured concentrations were within ±25% of the certified values. Using [13C]-IS eliminated the need for matrix-matched calibration standards for quantitation, simplified sample preparation, and achieved simultaneous identification and quantitation of the aflatoxins in a simple LC-MS/MS procedure.
开展了一项实验室间研究，以评估稳定同位素稀释法和液相色谱串联质谱法（MS/MS）用于测定牛奶、婴幼儿配方奶粉（配方奶粉）和饲料中的黄曲霉毒素B1、B2、G1、G2和M1（AFB1、AFB2、AFG1、AFG2和AFM1）。首先向样品中添加与五种天然黄曲霉毒素对应的五种13C均匀标记的黄曲霉毒素{[13C]-内标（IS）}，随后用乙腈-水（50 + 50，v/v）进行提取，接着进行离心、过滤和LC-MS/MS分析。除了认证奶粉和动物饲料外，三个参与实验室还分析了添加了浓度范围为0.5至50 ng/g的五种黄曲霉毒素的牛奶、配方奶粉和饲料。大多数回收率在80%至120%之间，相对标准偏差（RSD）< 20%。三个实验室使用三种样品基质重复进行测定（n = 8）来确定方法定量限（LOQ），所测定的AFB1、AFB2、AFG1、AFG2和AFM1的LOQ分别为0.1至0.91、0.24至0.64、0.28至1.52、0.19至3.80和0.12至0.45 ng/g。对于认证材料中检测到的黄曲霉毒素，所有测量浓度均在认证值的±25%范围内。使用[13C]-IS消除了定量时对基质匹配校准标准品的需求，简化了样品制备，并在简单的LC-MS/MS程序中实现了黄曲霉毒素的同时鉴定和定量。
