On the basis of the experiments that have been performed, it is possible to determine the effectiveness of the ozonization of iodized X-ray contrast media using IC-ICP-MS via the amount of iodate formed. Whereas a 120-minute ozonization guarantees a practically quantitative decomposition of amidotrizoic acid to iodate, approximately 16% of the Iomeprol is still present under the same ozonization conditions. Given that only 14% is present in iodate form in the absence of iodide anions and given that additional, not yet identified peaks occur in the ion chromatogram, the presence of additional decomposition products containing iodine must be assumed. Nonetheless, it is not possible to detect the intact iodized X-ray contrast media with the selected ion chromatographic conditions. Furthermore, the possibility exists of identifying the peak of the unknown decomposition product of the Iomeprol using IC-ESI-TOF-MS.