Liquid chromatography was performed using a Waters Acquity UPLC system (Waters, UK). To validate for a broad range of compounds, three chromatographic methods have been applied. Sample preparation was the same for all methods, but respective analytical methods did vary (figure ). Analysis for group A (covering a broad range of pharmaceuticals) consists of two LC-MS/MS methods (ESI + and -). For group B focusing on AAs, one LC-MS/MS method has been developed (ESI+).