Abstract: According to the requirements and methods of “Guide to the evaluation and expression of uncertainty in measurement” (CNAS–CL01–G003), and “Guide for evaluation of uncertainty in chemical analysis for measuring uncertainty” (CNAS–GL006), analyses the uncertainty of iodine content testing in drinking water by ICP-MS, and evaluated all the components of measuring uncertainty, in order to find out the influent factors and provide scientificbasis for the evaluation. The results show that when the content of arsenic in drinking water is (8.9±0.9) μg/L(k=2). From the analyzing process, we know that standard curve fitting and the testing instrument are the most important components to uncertainty component.

Key words: Inductively Coupledplasma Mass Spectrometry, Drinking water, Iodine, Uncertainty