Drug abuse is a worldwide well-known problem. Although current analysis of drug biomarkers in blood and urine is well established in forensic toxicology, compounds are only detectable for a small time period. At present, the analysis of a keratinized matrix (hair) is the only option to detect biomarkers over a longer time period. However, hair analysis faces crucial technical and interpretative obstacles, complicating unambiguous interpretation of drug use or exposure. Therefore, we aim at developing a generally applicable workflow to monitor hemoglobin (Hb) and/or human serum albumin (HSA) adducts, which will serve as biomarkers with an extended window of detection (up to several weeks), upon exposure to typical illicit drugs. In a first part of this project, we aim at setting up sensitive LC-HRMS and LC-MS/MS-based detection of in vitro generated protein adducts (Hb and HSA), formed upon incubation with cocaine, morphine or THC. Since the major challenge of this project lies in the sensitive monitoring of minute quantities of proteins adducts in the presence of a large excess of unmodified proteins, approaches to deplete the unmodified proteins and/or to enrich the targeted peptides will be applied. In a second phase of this project, the developed workflow will be applied to authentic drug positive samples, hence evaluating the applicability of the method to detect in vivo covalent protein adducts. Finally, our final goal is to apply the workflow in 'historic' case samples.