Determination of Total Iodine using ICP-MS in Israeli Bottled and Tap Water: Method Development and Application

Vasiliy Rosen, Faculty of Agriculture, The Hebrew University of Jerusal, Rehovot, Israel (icpaes@gmail.com)

Reliable iodine determination in drinking water samples has gained importance in the last few decades, mostly due to intensive use of both desalinized water that lacks several important nutritional elements, and bottled mineral water.  ICP-MS is a sensitive method for iodine determination that must be performed under alkaline conditions because of the volatile nature of some iodine species. However, in water samples with high pH (>10), slow precipitation of calcium (Ca) and/or magnesium (Mg) carbonates leads to clogging of the ICP-MS nebulizer.

We propose preventing this precipitation by adding the chelating agent ethylenediaminetetraacetic acid (EDTA) at 0.1% to a 2% ammonium hydroxide matrix. This concentration of EDTA sufficed for most drinking water samples studied, as long as a 1:1 molar ratio of EDTA to Ca+Mg concentration in the water was maintained. The limit of quantitation of the developed method for iodine was <0.1 µg/L (ppb).

The average iodine concentration in various brands of bottled mineral water sold in Israel was relatively low (7.67 ± 6.38 µg/L). Regular consumption of either desalinated water or bottled mineral water may induce iodine deficiency in Israeli consumers. Therefore, continuous follow-up of the iodine status in both tap and bottled water is strongly recommended.

Totally 20 tap water samples were taken from different Israeli cities or villages (from households and non-residential premises) from North to South. Also, 13 desalinized water samples from 3 desalination plants were analyzed. The range of total iodine content in tap water was 0.2-19.9 µg/L, whereas in desalinized water – <0.1 – 0.85 µg/L. Total iodine was correlated positively and significantly with Na, K, Mg, and S, but in most cases not with Ca.

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Short Biography of Presenting Author

Senior-level ICP-OES/MS expert with more than 20 years experience.

Expert in sample preparation and elemental analysis of wide range of samples.

Ph.D. in soil science (Department of Soil and Water, Faculty of Agriculture, The Hebrew University of Jerusalem).

Current position: Director of the Plasma Spectrochemistry Laboratory (ICP-OES/MS), The Scientific Core Facility, HUJI.

Scientific interests: distribution pattern of trace metals in soils, metal accumulation in plants, trace metals in food and water.