Pressurized liquid extraction and liquid chromatography-tandem mass spectrometry applied to determine iodinated X-ray contrast media in sewage sludge.

Pressurized liquid extraction (PLE) has been successfully applied for the first time to the extraction of five iodinated X-ray contrast media from sludge. Once optimized all PLE parameters, the extract has been analyzed by liquid chromatography-tandem mass spectrometry, being the method developed sensible enough to reach limit of quantifications (LOQs) of 25 μg kg(-1) (d.w.). The developed method has been applied to the analysis of sludge from urban sewage treatment plants and although some compounds such as iopromide, diatrizoic acid and iopamidol have been identified, their concentrations have been lower than their LOQs.