Ž . The Science of the Total Environment 255 2000 129134 Occurrence of triiodinated X-ray contrast agents in the aquatic environment Anke Putschew  , Sabine Wischnack, Martin Jekel Technical Uni  ersity of Berlin, Institute for En ironmental Technology, Department of Water Quality Control, Sekr. KF 4, Strasse des 17 Juni 135, 10623 Berlin, Germany Received 21 January 2000; accepted 6 March 2000 Abstract Ž . High concentrations of adsorbable organic iodine AOI are found in municipal treatment plant effluents and surface waters by specific organic halogen determination. The high AOI is caused by widely used triiodinated X-ray contrast agents, which are very stable and hydrophilic. We have analysed specifically surface water influenced by a municipal treatment plant effluent, the surface water after bank filtration and raw drinking water. The X-ray contrast agents were determined by liquid chromatography-mass spectrometry with positive electrospray ionization after enrichment by solid phase extraction. Diatrizoate and iopromide, two triiodinated contrast agents are detectable in all samples, whereby the less polar component iopromide seems to be reduced during bank filtration. Just a trace of iopromide is identified in surface water after bank filtration and in the raw drinking water. Approximately 60% of the initial AOI is extractable and approximately 25% of the extractable AOI can be identified as specific triiodinated contrast agents.  2000 Elsevier Science B.V. All rights reserved. Keywords: Triiodinated benzene derivatives; Contrast agents; Iopromide; Diatrizoate; Liquid chromatography-mass spectrometry 1. Introduction Triiodinated benzene derivatives are widely used as X-ray contrast agents. Triiodinated com-  Corresponding author. Tel.:49-30-314-25480; fax: 49- 30-314-23850. Ž E-mail address: putschew@itu203.ut.tu-berlin.de A. . Putschew . pounds enhance the contrast between organs and the surrounding tissues and enable visualization of organ details which otherwise could not be investigated. The contrast media are applied by intravenous injection and are rapidly eliminated via urine or faeces. Due to the high hydrophilicity of the substituted benzene derivatives they pass waste water treatment plants and thus, are ex- pected to be found in rivers, lakes and raw 0048-969700$ - see front matter  2000 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 0 4 8 - 9 6 9 7 00 00461-7