Abbott Nutrition, 3300 Stelzer Rd, Columbus, OH 43219, United States.
J AOAC Int. 2024 Jan 4;107(1):103-111. doi: 10.1093/jaoacint/qsad104.
The AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals issued a call for methods for the determination of fluoride in infant formula. Standard Method Performance Requirement (SMPR®) 2014.016 was approved.
A single-laboratory validation (SLV) of a fluoride ion-selective electrode (F-ISE) method was completed.
Five powder samples were reconstituted, and hydrochloric acid was added to dissolve and release any bound fluoride. Samples included infant and adult nutritional products made from milk, whey, or soy, containing intact, partially hydrolyzed, or hydrolyzed proteins. Sodium citrate buffer was added to complex any interfering ions and adjust pH and ionic strength. Samples were analyzed in duplicate over 6 days using F-ISE.
Results were calculated based on one of two least-squares (log fit) standard curves (0.02 to 0.1 µg/100 g or 0.1 to 2.0 µg/100 g). The LOQ for the method was determined to be 3.3 µg/100 g, which was far below the minimum analytical value of 30 µg/100 g required in the SMPR. The fluoride concentrations ranged from approximately 3 to 14 µg/100 g reconstituted powder and the intermediate precision, RSDr, ranged from 0.7 to 12.4%. Although all of these results are out of scope for the SMPR due to their low fluoride, it should be noted that the RSDr for formulas with fluoride concentrations ranging from approximately 9 to 14 µg/100 g ranged from 0.7 to 4.3%, and the RSDr for the two formulas with fluoride concentrations at or below the theoretical detection limit of the method were only approximately10 and 12.4%. Recoveries ranged from 94 to 98% for samples spiked at three levels with NIST-traceable standard solutions, meeting the SMPR.
The F-ISE method meets the SMPR and was adopted as a First Action Official MethodSM.
The fluoride ion-selective electrode method presented here is affordable and easy to run. The addition of acid to the samples dissolves any minerals which may bind the fluoride.
AOAC 利益相关者小组发布了婴儿配方食品和成人营养用氟化物测定方法的征集。已批准标准方法性能要求（SMPR®）2014.016。
完成了氟离子选择性电极（F-ISE）方法的单实验室验证（SLV）。
将五种粉末样品复溶，加入盐酸溶解并释放任何结合的氟化物。样品包括来自牛奶、乳清或大豆的婴儿和成人营养产品，含有完整的、部分水解的或水解的蛋白质。加入柠檬酸钠缓冲液络合任何干扰离子并调节 pH 值和离子强度。使用 F-ISE 在 6 天内重复分析两次。
结果基于两条最小二乘法（对数拟合）标准曲线之一（0.02 至 0.1μg/100g 或 0.1 至 2.0μg/100g）计算得出。方法的 LOQ 确定为 3.3μg/100g，远低于 SMPR 要求的 30μg/100g 最低分析值。氟化物浓度范围约为 3 至 14μg/100g 复溶粉末，中间精密度，RSDr，范围为 0.7 至 12.4%。尽管由于氟化物含量低，所有这些结果均超出 SMPR 的范围，但应注意，氟化物浓度约为 9 至 14μg/100g 的配方的 RSDr 范围为 0.7 至 4.3%，氟化物浓度等于或低于方法理论检测限的两个配方的 RSDr 仅约为 10%和 12.4%。用 NIST 可追踪标准溶液在三个水平上进行加标回收试验，回收率为 94%至 98%，符合 SMPR。
F-ISE 方法符合 SMPR，并被采纳为第一行动官方方法 SM。
这里介绍的氟离子选择性电极方法价格实惠且易于运行。向样品中添加酸可溶解任何可能与氟化物结合的矿物质。
