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

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.