The use of filtration/pass-through extraction (FPTE) and ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC–qTOF–MS) to detect tramadol (TRAM), dextromethorphan (DXM), and metabolites from skeletal remains is described. Rats (n=5) received 50 mg/kg tramadol and were euthanized by CO2 asphyxiation approximately 30 minutes post-dose. Rats (n=4) received 75 mg/kg dextromethorphan and were euthanized by CO2 asphyxiation approximately 45 minutes post-dose. Remains decomposed to skeleton outdoors and vertebral bones were collected. Bones were cleaned, dried, and pulverized to a fine powder. Bones underwent dynamic methanolic extraction followed by FPTE before analysis using UPLC–qTOF–MS. Recovery was at least 90% of maximal value within the first 10 minutes of methanolic extraction for all samples assayed. Analytical response was measured over the concentration range of 1–500 ng/mL, with precision and bias <20% in triplicate analyses of all calibrators, and a limit of detection of 1 ng/mL for TRAM, DXM, and all metabolites. The vertebral bone analyzed using this method detected TRAM, DXM, and their respective metabolites in all samples analyzed.