Further Extensive Evaluation of GHB‐Pentose as a Novel Biomarker for the Extended Detection of GHB Intake/Administration in Forensic Casework

ABSTRACT Gamma‐hydroxybutyrate (GHB) detection in forensic toxicology is hampered by its rapid elimination and endogenous occurrence. GHB‐pentose has recently emerged as a promising biomarker capable of extending the detection window of GHB exposure but requires further evaluation in authentic forensic samples. We systematically investigated GHB‐pentose using two independent LC–MS/MS methods based on hydrophilic interaction liquid chromatography (HILIC) and reversed‐phase (RP) chromatography. Positive findings were evaluated against measured GHB concentrations, case information, matrix type, and concordance between analytical methods. Among 2414 urine cases, 97.6% were negative for GHB and GHB‐pentose. GHB‐pentose could be detected in all 21 GHB‐positive urine samples from living individuals and in four GHB‐positive postmortem cases, whereas 20 other postmortem urine samples with elevated GHB concentrations (10–26 mg/L) were negative for GHB‐pentose. Based on toxicological expert assessment performed independently prior to this study, it was assumed that the GHB detected in these cases was more likely the result of postmortem formation than of prior GHB intake. Fourteen GHB‐negative urine samples were positive for GHB‐pentose; eight of these contained case information supporting previous GHB exposure, including three suspected drug‐facilitated crimes sampled 13–16 h after the incident. GHB‐pentose appears to be a highly specific biomarker of exogenous GHB exposure, capable of extending the detection window beyond that of GHB itself and potentially serving as a discriminant between exogenous GHB administration and endogenous, particularly postmortem, GHB formation. Routine LC–MS/MS screening is feasible, even in the absence of a reference standard, supporting its immediate implementation in forensic toxicology workflows.