Determination of iodine using a special sample introduction system coupled to a double-focusing sector field inductively coupled plasma mass spectrometer

Abstract

A procedure for the determination of iodine (especially ¹²⁹I) in biological materials using double-focusing sector field mass spectrometry with an inductively coupled plasma ion source is described.

To achieve a detection limit of less than 100 pg ml^–1 for ¹²⁹I by double-focusing sector field ICP-MS an apparatus for introducing elemental iodine via the gas phase into the argon plasma is tested. The influence of the concentration of various oxidation reagents for oxidizing iodide to iodine and matrix effects on the ion intensity of ¹²⁹I⁺ and ¹²⁷I⁺ are investigated. Quantitative determination of iodide is carried out by the standard additions procedure and isotope dilution analysis. The on-line addition of sample solution to an isotopic tracer solution according to the flow injection principle has proved to be efficient. The procedure is discussed by determining ¹²⁷I as well as ¹²⁹I in biological standard reference materials.