Project management
Dr. phil. nat. Stefan König, Forensic Toxicology and Chemistry, Institute of Forensic Medicine, University of Bern
Project participants
Dr. ès Sc. Susanne Nussbaumer, Forensic Toxicology and Chemistry, Institute of Forensic Medicine, University of Bern
Thomas Wüthrich, Forensic Toxicology and Chemistry, Institute of Forensic Medicine, University of Bern
Dr. ès Sc. Marie Martin, Forensic Toxicology and Chemistry, Institute of Forensic Medicine, University of Bern
Prof. Dr. rer. nat. Wolfgang Weinmann, Forensic Toxicology and Chemistry, Institute of Forensic Medicine, University of Bern
Dr. phil. nat. Stefan König, Forensic Toxicology and Chemistry, Institute of Forensic Medicine, University of Bern
Project data
Funding institution: IRM Bern
Funding period: seit 2014
Abstract
Fast and accurate screening is an important step for the identification of drugs and their metabolites. Quite often, the active compound is no longer detectable and therefore it is essential to detect metabolites in order to verify consumption or abstinence. Based on the latest generation of Qq-ToF mass spectrometers, urine and blood samples from forensic cases were measured by SWATH acquisition, and analyzed for the presence of potential metabolites by target processing. Methods: Urine samples were diluted with a mixture of water / acetonitrile / formic acid / ammonium formate and three internal standards were added. The samples were injected onto a core shell column and analyzed on a Qq-ToF instrument (5600 TripleTof, AB Sciex, Concord, CA) in data independent SWATH acquisition mode (sequential window acquisition of all theoretical fragment ion spectra).
These samples are then processed by a target list of all currently known metabolites for a subset of forensic relevant compounds (e.g. illicit drugs, antidepressants, hypnotics, tranquilizers, designer drugs etc.). The MS/MS spectra of each detected metabolite are then verified with published literature spectra as well as with internet search engines (e.g. www.chemspider.com, www.massbank.eu). The MS/MS spectra obtained by SWATH acquisition were then compared with existing high-resolution high accuracy MS/MS spectra – which are mainly acquired by infusion or data dependent experiments – in relation to accuracy, and relative signal intensity. These newly obtained results indicate that SWATH acquisition shows good overlapping with existing spectra and therefore allows complete identification.
Essentially, an appropriate chromatographic separation followed by SWATH acquisition allows for unambiguous identification of known or in silico predicted metabolites even if no synthesized reference standards are available.
