Development of ICP-MS Method for Measurement of Total Iodine in Water for Official Survey of Iodine Occurrence in Israeli Drinking Water Sources

Luda Groisman, National Public Health Laboratory, Ministry of Health, Tel Aviv, Israel (luda.groisman@phlta.health.gov.il)
Danny Iny, National Public Health Laboratory, Ministry Of Health, Tel Aviv, Israel
Elena Raitsis, National Public Health Laboratory, Ministry Of Health, Tel Aviv, Israel
Irit Hen, Environmental Health Department, Ministry Of Health, Jerusalem, Israel
Efrat Rorman, National Public Health Laboratory, Ministry Of Health, Tel Aviv, Israel

Iodine intake level is important for the occurrence of thyroid disorders in the population, and both high and low iodine intake levels are associated with increased risk of disease. Dietary iodine content is decisive for the intake of iodine and water is a ubiquitous source of dietary iodine .Iodine occurs naturally in water presumably predominantly in the iodide form. The concentration of total iodine in drinking-water may vary from micrograms to hundreds of micrograms per liter in different regions.
Due to the complexity of the water system in Israel and the need to calculate mineral concentrations supplied to drinking-water consumers, the Ministry of Health promotes development of models for calculation of mineral species ( Ca, Mg, I ) in supplied drinking water. Because Ca and Mg are included in Israeli drinking water regulations, there is an extensive database of their yearly occurrence in water sources, whereas there is no such database for iodine. There is a lack of analytical methods for measurement of low levels of total iodine in water. A Ministry of Health initiated national survey tested 360 different water sources for total iodine. The ICP-MS method was developed and validated in the National Public Health Laboratory, using 25% tetramethyl ammonium as stabilization solution and rhodium as internal standard. Limit of detection and quantification were 0.6 and 2.0 µg/L, accuracy and precision were 105% and 9% and 99% and 2% for low and mid concentration levels respectively. Iodine concentrations in Israeli water sources varied from <2 to 150 µg/L.