The urine samples from the case study and the spiked urine, plasma and serum samples for the LOD comparison were prepared using the optimized protocol by Oesterle et al. . The samples were stored at -80°C until analysis. The concentrations of the spiked samples are reported in Table . Enzymatic hydrolysis of glucuronides and sulfates was intentionally not performed in this work to be able to perform neutral loss queries of the features.