Abstract: To address the need for iodine quantification in infant formula food for special medical purposes, a reference material for iodine analysis was developed. Powered infant formula milk for special medical purposes (containing partially hydrolyzed milk protein) was used as the matrix and added with dietary supplement of potassium iodide initially diluted with whey protein powder to establish a stable preparation system using stepwise dry dilution. The homogeneity and stability of the prepared reference material were verified using alkaline extraction combined with inductively coupled plasma mass spectrometry, and characteristic value assignment was conducted through a multi-laboratory collaborative approach. Results demonstrated excellent homogeneity and stability of the material, showing a characteristic value for iodine of (67.8 ± 4.6) μg/100 g (k = 2). This reference material could be useful for method validation, laboratory quality control, and instrument calibration for iodine determination in infant formula food for special medical purposes, providing technical support for ensuring accurate measurement of iodine content in this specialized food product.

Key words: standard reference material; iodine; infant formula food for special medical purposes; homogeneity; stability

摘要： 针对特殊医学用途婴儿配方食品中碘含量测定需求，研制一种碘成分分析基质标准物质。以特殊医学用途婴儿配方乳粉（乳蛋白部分水解配方）为基质，采用包埋碘化钾为添加物，经乳清蛋白粉初级稀释后，采用干法逐级放大混合稀释制备技术，建立了稳定的标准物质制备体系。采用碱液提取-电感耦合等离子体-质谱法对标准物质的均匀性和稳定性进行检测，并采用多实验室定值的方法对标准物质的特性值赋值。结果表明，该标准物质具有良好的均匀性和稳定性，碘含量特性值为（67.8±4.6）μg/100 g（k＝2）。该标准物质可用于特殊医学用途婴儿配方食品中碘含量测定方法的验证、实验室质量控制及仪器校准，为特殊医学用途婴儿配方食品中碘的准确测定提供可靠的技术支撑。

关键词: 标准物质；碘；特殊医学用途婴儿配方食品；均匀性；稳定性