碳酸钠-氧化锌半熔电感耦合等离子体质谱法测定地球化学样品中的碘

何袖辉; 唐帅帅; 程江; 石友昌; 陆迁树; 王银剑; 兰明国

doi:10.15898/j.cnki.11-2131/td.202106090074

碳酸钠-氧化锌半熔电感耦合等离子体质谱法测定地球化学样品中的碘

Determination of Iodine in Geochemical Samples by ICP-MS with Sodium Carbonate-Zinc Oxide Semi-melting

摘要

摘要: 应用电感耦合等离子体质谱法(ICP-MS)测定地球化学调查样品中的碘，主要采用封闭溶样、混合酸溶、碱熔和半熔法进行样品处理，但由于碘在土壤和沉积物中的存在形态较为复杂，有高碘酸根、碘酸根、碘离子，且碘为卤族元素，第一电离能较高，在样品处理及上机测定环节中存在溶出不彻底、记忆效应强、稳定性较差等问题。本文采用碳酸钠-氧化锌半熔法处理样品，乙醇-沸水提取后用732型阳离子交换树脂将溶液中大量阳离子分离，采用内标法ICP-MS测定样品溶液中的碘。通过优化溶样程序提升了样品溶出效果，优化测定介质及内标元素消除记忆效应，提升了结果稳定性，建立了一套完善的ICP-MS测定碘的方法。使用土壤和沉积物国家一级标准物质进行方法验证，方法检出限为0.045μg/g，方法检测下限为0.15μg/g，方法精密度(RSD，n=12)≤5.93%，方法准确度△logC≤0.01，符合地球化学调查样品分析测试要求，可推广应用于地球化学调查中大批量土壤和沉积物样品的分析测试。

Abstract:
BACKGROUND The determination of iodine in geochemical samples by inductively coupled plasma-mass spectrometry (ICP-MS) is treated mainly by closed sample melting, mixed acid solution, alkali fusion and semi-melting method. However, due to the complex existent morphology of iodine in soil and sediment samples, including periodate, iodate and iodide ions, and the first ionization energy of iodine being high as a halogen group element, there are problems such as incomplete dissolution, strong memory effect and poor precision during sample processing and measurement.
OBJECTIVES To improve the determination of iodine in geochemical samples by ICP-MS.
METHODS The samples were treated by sodium carbonate-zinc oxide semi-melting method, extracted with boiling water-ethanol, and separated by 732 cation exchange resin. Following this, iodine in the solution was determined by ICP-MS using an internal standard method.
RESULTS The optimized detection limit of iodine was 0.045μg/g, the lower limit of detection was 0.15μg/g. The precision (RSD, n=12) and the accuracy (△logC) of the method were ≤5.93% and ≤0.01, respectively, which satisfied the analysis standards of geochemical survey sample.
CONCLUSIONS This method meets the requirements of sample analysis for geochemical investigation, and can be used for the analysis of iodine in large quantities of soil and sediment samples.

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