Optimized UPLC-MS/MS Assay for Therapeutic Drug Monitoring in Patients with Adenine Phosphoribosyltransferase Deficiency Margret Thorsteinsdottir (1,2), Unnur A. Thorsteinsdottir (1,2), Hrafnhildur L. Runolfsdottir (3), Finnur F. Eiriksson (2), Vidar O, Edvardsson (1,3), Runolfur Palsson (1,3) (1) University of Iceland, Reykjavik, Iceland (2) ArcticMass, Reykjavik, Iceland (3) Landspitali–The National University Hospital of Iceland, Reykjavik, Iceland Margret Thorsteinsdottir, PhD (Presenter) University of Iceland Presenter Bio: Professor in Pharmaceutical Analytical Chemistry at the Faculty of Pharmaceutical Sciences, University of Iceland and R&D Director of ArcticMass LTd, Reykjavik, Iceland. Dr. Thorsteinsdóttir received her PhD from Uppsala University, Sweden in 1998. From 2000 to 2009 she was the managing director of Bioanalytical Laboratories at deCODE Genetics, Reykjavik, Iceland. She has extensive experience in development of analytical methods for metabolite profiling and quantification of clinical biomarkers in various biofluids utilizing chemometrics with the goal of improved clinical management of patients towards personalized patient care. Her current research interest includes studies of lipid metabolism in cancer cells and profiling plasma derived biomarkers for early detection of BRCA-related breast cancer. She is responsible for implementation of clinical mass spectrometry for support of diagnostics and therapeutic drug monitoring in collaboration with ArcticMass and the Landspitali University Hospital, Reykjavik, Iceland with major focus on quantitative targeted proteomics for clinical diagnosis. She is a principal investigator of the Icelandic Research Rannis projects, profiling metabolites for breast cancer diagnosis and search for novel biomarkers for early breast cancer diagnosis by metabolomics. Dr. Thorsteinsdóttir is a principal investigator for the Marine Biotechnology ERA-net project CYNOBESITY and the Horizon 2020 project MossTech, with the main task to isolate, identify and structurally characterize bioactive compounds from cyanobacteria, Icelandic mosses and liverworts. She is one of the founders of Females in Mass Spectrometry (FeMS), she is a vice-leader of the working group clinical significance and applications of (epi)lipidomics in the pan-European network, EpiLipidNET and vice-chair of the Nordic Metabolomics Society.