A procedure for the quantification of total iodine by inductively coupled plasma mass spectrometry, and its application to the determination of iodine in algae sampled in the lagoon of Venice

Abstract

A procedure for the analysis of total iodine by inductively coupled plasma mass spectrometry (ICP-MS) is proposed, in order to overcome the memory effects and recovery problems highlighted in the literature, which are mainly due to the easy volatilization of iodine during the several analytical steps. The microwave mineralization is performed in aqua regia. After dilution with water and before the injection into the ICP-MS, the solution is added with 0.1 M NH₄SCN. Suitable calibration conditions (KIO₃ as the iodine standard, 0.69% w/w HNO₃ as the medium, and 0.1 M NH₄SCN) were individuated. The calibration sensitivity, recovery and limit of detection (LOD) were obtained. This procedure allowed the simultaneous determination of most of the other elements usually analysed by ICP-MS, with the exceptions of Ag, Ba, S, and partly also Pb. The procedure was then used to determine total iodine in selected seaweed samples (Sargassum muticum (Harvey) Suringar, SM, and Undaria pinnatifida (Yendo) Fensholt, UP) collected in six sites around Venice, where no iodine bio-monitoring has been hitherto performed.