Interference of the novel designer benzodiazepine 4ʹ-chloro deschloroalprazolam with alprazolam analysis in toxicology and seized drug DUID casework.

This article focuses on the identification challenges posed by the novel designer benzodiazepine 4ʹ-chloro deschloroalprazolam, an isomer of alprazolam, in forensic toxicology. The Houston Forensic Science Center (HFSC) developed an interference study using liquid chromatography–tandem mass spectrometry (LC–MS-MS) to differentiate 4ʹ-chloro deschloroalprazolam from alprazolam based on their retention times relative to the internal standard alprazolam-d5, since the two compounds share similar mass spectra and cannot be chromatographically resolved by existing methods. Case analyses revealed instances where 4ʹ-chloro deschloroalprazolam was present in seized drug materials and toxicological samples without alprazolam, highlighting the potential for misidentification and interference in quantitation. The study underscores the importance for forensic laboratories to recognize and adapt to emerging designer benzodiazepines to avoid false-positive identifications of controlled substances.