Wolf Wayne R, Goldschmidt Robert J
Food Composition Laboratory, BHNRC, ARS, USDA, Beltsville, MD 20705, USA.
Anal Bioanal Chem. 2004 Mar;378(5):1175-81. doi: 10.1007/s00216-003-2393-0. Epub 2004 Jan 21.
Values of the total selenium and selenomethionine (Semet) content of four wheat-based reference materials have been obtained by gas chromatography-stable isotope dilution mass spectrometry methods. The total Se method is an established one, and the results obtained with it are consistent with previously-assigned values. The Semet method (previously reported by our laboratory) is based on reaction with CNBr. Our data indicate that the four wheat samples (wheat gluten, durum wheat, hard red spring wheat, and soft winter wheat), though having a 30-fold range in total Se content, all have about 45% of their total Se values in the form of selenomethionine. Investigation of the CNBr-based method suggests that additional experiments are needed to verify that all selenomethionine in the wheat samples is accounted for, but also indicates that the values obtained are within 15% of the true values. As the form in which Se occurs in foods and dietary supplements is important from a nutritional perspective, adding information about Se speciation to total Se values in appropriate reference materials makes these materials more valuable in relevant analytical work.
采用气相色谱-稳定同位素稀释质谱法测定了四种小麦基标准物质中总硒和硒代蛋氨酸（Semet）的含量。总硒测定方法是一种成熟的方法，所得结果与先前指定的值一致。Semet测定方法（此前由我们实验室报道）基于与溴化氰的反应。我们的数据表明，这四个小麦样品（小麦面筋、硬质小麦、硬红春小麦和软冬小麦），尽管总硒含量范围相差30倍，但所有样品中约45%的总硒以硒代蛋氨酸的形式存在。对基于溴化氰的方法进行研究表明，需要进行额外的实验来验证小麦样品中的所有硒代蛋氨酸都已被测定，但也表明所得值在真实值的15%以内。由于从营养角度来看，食品和膳食补充剂中硒的存在形式很重要，因此在适当的标准物质中添加有关硒形态的信息，会使这些物质在相关分析工作中更具价值。
