KOH快速消解/ICP-MS测定婴幼儿乳粉中总碘含量  

Determination of Total Iodine in Infant Formula by KOH Digestion and Inductively Coupled Plasma Mass Spectrometry

作　　者：李姗 何霜 李吉龙 李俞洁 方军[2] 冼燕萍 黄金凤 郭新东 

机构地区：[1]广州质量监督检测研究院,广东广州510110 [2]中国广州分析测试中心,广东广州510070

出　　处：《分析测试学报》2016年第7期864-868,共5页Journal of Instrumental Analysis

摘　　要：建立了一种简便、快速地测定不同乳粉基质中总碘含量的KOH快速消解/ICP-MS方法。优化了KOH溶液的浓度和消解温度等因素,并探讨了消解后溶液的稳定情况。结果表明,在105℃下,5%KOH溶液可在1 h内完全消解乳粉样品中的总碘,消解后的碘离子在氨水-Na2S2O3溶液中可稳定存在48 h,用141Pr作内标,ICP-MS直接测定其滤液中的碘含量,该方法相对于国标GB 5413.23-2010法减少了复杂的前处理沉淀和衍生萃取操作。碘的标准曲线在0～100μg/L浓度范围内呈良好线性,相关系数为1.000 0,方法检出限为1.5μg/kg。对标准物质GBW 10017、NIST SRM 1849a、奶基乳粉、豆基乳粉进行测定,测得样品的加标回收率为88.2%～107.4%,重复性和再现性相对标准偏差均小于5%,标准物质GBW 10017和NIST SRM 1849a的测定值与标示值一致。该方法准确、灵敏高、回收率好,适用于不同乳粉基质中总碘含量的测定。A simple and rapid method was established for the determination of total iodine in different infant formulas by oven fast digestion with KOH solution combined with inductively coupled plasma mass spectrometry （ ICP - MS）. Concentration of KOH solution and temperature of digestion were op- timized, and the stability of the digestion solution was investigated. The result indicated that the in- fant formula samples could be completely digested with 5% KOH solution in 1 h under 105 ℃ , and the iodine ion could be stable for 48 h in the stabilizer of ammonia - Na2S2O3 solution. Using 141 Pr as the internal standard, the iodine contents of the filtrate were determined by inductively coupled plas- ma mass spectrometry（ICP- MS）. The method could reduce the complex sample processings such as pretreatment precipitation and derivative extraction compared with the national standard method （GB 5413.23 -2010）. Iodine presented favorable linearity in the range of 0 -100 μg/L with correlation coefficient（r） of 1. 000 0, and the method detection limit was 1.5μg/kg. By means of determing the national standard material GBW 10017, NIST SRM 1849a and milk powders with different matri- ces, recoveries of 88.2% - 107.4% were obtained and RSDs for repeatability and reproducibility were less than 5% . The iodine determined by the national standard material GBW 10017 and NIST SRM 1849a presented no significant differences between measured values and certified values. The method showed the advantages of sensitivity, accurancy and satisfactory recovery, and was suitable for the determination of total iodine in different infant formula matrices.

关 键 词：KOH消解 电感耦合等离子体质谱 碘 婴幼儿乳粉 

分 类 号：O657.63[理学—分析化学] O613.44[理学—化学]