An unusual detection: tert-butyl-4-anilinopiperidine-1-carboxylate (4-Anilinopiperdine-t-BOC) found in seizures of falsified 'Xanax' tablets and also detected amongst items in a suspected heroin seizure submitted by Irish law enforcement.

The identification of tert-butyl-4-anilinopiperidine-1-carboxylate (4-anilinopiperdine-t-BOC, 4-AP-t-BOC) as an ingredient in a number of seized falsified 'Xanax' tablets is reported after being encountered in forensic casework in late 2019 and early 2020 in Ireland. This substance was also detected in pink powder submitted for analysis to the laboratory in March 2020. This submission comprised mainly of brown powders containing morphine or diamorphine (heroin) or a type of counterfeit heroin or heroin adulterant (known as 'bash'). Novel benzodiazepines and other substances are being detected as ingredients in falsified benzodiazepine tablets more frequently on the illicit market and the detection of 4-AP-t-BOC in tablets is noteworthy as it adds to the list of adulterants found in benzodiazepine tablets emerging recently in Europe. The presence of 4-AP-t-BOC in both falsified 'Xanax' and powdered seizures is unusual, and analytical data is presented to assist with its identification in submissions of suspected illicit substances. The presence of 4-AP-t-BOC in the tablets was confirmed by GC-MS and LC-MS analysis and suggested spectral fragmentation pathways are presented. To the authors' best knowledge, information about the biological activity of 4-AP-t-BOC is not available. Removal of the t-BOC protecting group yields 4-anilinopiperidine (4-AP) which has been reported to be involved in the synthesis of fentanyl.