同位素稀释电感耦合等离子体质谱法测定食品中的碘

采用同位素稀释法结合密封玻璃管的提取技术，建立了准确、灵敏的食品样品中碘的电感耦合等离子体质谱法（ID-ICP-MS）分析方法。样品中添加碲（128Te）同位素内标，以四甲基氢氧化铵（TMAH）为提取液，采用烧结玻璃试管密封，水浴振荡浸提样品中的碘，电感耦合等离子体质谱法测定，同位素稀释内标法定量。结果表明，碘在0.025 μg/L-50 μg/L范围内线性线性关系良好，相关系数为0.9999，线性方程为y=1.0506 x＋1.2511；当取样质量为0.1 g时，方法的检出限为1.8 μg/kg；在2.50、5.00和10.00 mg/kg 3个低、中、高添加水平，加标回收率在80.29%-104.70%之间，方法相对偏差小于5.0%；通过对海带标准物质GBW08517的测定，表明测定值与标准值之间无显著性差异。本方法简便、准确、灵敏度高，适用于多类食品中碘含量的测定。

Determination of Iodine in Food by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

A method for the determination of iodine in food by isotope dilution inductively coupled plasma mass spectrometry （ID-ICP-MS） was established, combined with sealed glass tube extraction technology. After addition of the isotopic labeled Tellurium （128Te） and tetramethylammonium hydroxide （TMAH） as extraction solution into a sealed glass tube, the homogenized sample was shocked in a water bath to obtain an extract suitable for analysis by ICP-MS, and the internal standard was used for quantitative analysis. Under the optional conditions, the linear range was between 0.025 μg/L and 50 μg/L with the linear correlation coefficients of 0.9999, and the linear equation was y = 1.0506x ＋1.2511. The detection limit was 1.8 μg/kg when the sample mass was 0.1 g. The mean recoveries for food samples at three spiked concentrations levels of 2.50, 5.00 and 10.00 mg/kg were ranged from 80.29% to 104.70% with relative standard deviation （RSD, n=6） less than 5.0%. The ID-ICP-MS method for determination of the iodine in standard material GBW08517 of kelp presented no significant differences between measured values and certified values. Due to the simplicity, accuracy and high sensitivity, this method was suitable for the determination of iodine in various of food.