Rao R R, Chatt A
Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Analyst. 1993 Oct;118(10):1247-51. doi: 10.1039/an9931801247.
Three different neutron activation analysis methods have been developed for the determination of ppb levels of iodine in food samples. The methods are based on the separation of iodine using (i) toluene extraction followed by bismuth sulfide coprecipitation; (ii) bismuth sulfide coprecipitation followed by radiochemical purification with palladium iodide; and (iii) radiochemical isolation by bismuth sulfide coprecipitation. The accuracy of these methods was evaluated by analysing replicate samples of reference materials. The measured values of iodine in A-11 Milk Powder, H-4 Animal Muscle and H-9 Mixed Human Diet from the International Atomic Energy Agency (IAEA) are statistically indistinguishable from the IAEA recommended values, and those for the Standard Reference Materials 1571 Orchard Leaves and 1577 Bovine Liver from the National Institute of Standards and Technology (NIST) are in good agreement with the NIST information values. The precision, in terms of relative standard deviation, is 5% at 50-100 ppb and 10% at 5-20 ppb levels of iodine. The absolute detection limits of these methods vary between 0.5 and 10 ng of iodine. All three methods were used to measure the iodine content of several food samples. The method involving bismuth sulfide coprecipitation followed by radiochemical purification provides the best detection limit and highest precision.
已开发出三种不同的中子活化分析方法来测定食品样品中十亿分之一水平的碘。这些方法基于以下碘的分离方法：（i）甲苯萃取后硫化铋共沉淀；（ii）硫化铋共沉淀后用碘化钯进行放射化学纯化；（iii）通过硫化铋共沉淀进行放射化学分离。通过分析参考物质的重复样品来评估这些方法的准确性。国际原子能机构（IAEA）的A-11奶粉、H-4动物肌肉和H-9混合人类饮食中碘的测量值与IAEA推荐值在统计学上无显著差异，美国国家标准与技术研究院（NIST）的标准参考物质1571果园树叶和1577牛肝中碘的测量值与NIST信息值高度一致。就相对标准偏差而言，在碘含量为50 - 100 ppb时精度为5%，在5 - 20 ppb时精度为10%。这些方法的绝对检测限在0.5至10 ng碘之间变化。所有三种方法都用于测量几种食品样品的碘含量。涉及硫化铋共沉淀后进行放射化学纯化的方法具有最佳的检测限和最高的精度。
