a sensitive method for the determination of iodine containing diagnostic agents in aqueous matrices using lcelectrospraytandemms detection iodinated contrast media belong to the most frequently applied compounds in medicine they exhibit a high polarity and are very persistent against metabolism by the organism and environmental degradation a sensitive method for the determination of five iodinated contrast media in aqueous matrices is described solid phase extraction utilizing isolute env material was used for sample enrichment the contrast media were partially separated on a rpc18 column and detection was achieved using electrospraytandem ms api iii plus and api 365 allowing the sensitive quantitation of these compounds down to the lower ngl range the recovery rates generally exceeded 70 for spiked surface water as well as tap water the analytes were detected in native samples such as municipal sewage treatment plant stp effluent the river rhine and even in tap water