Detection of AP-237 and synthetic cannabinoids on an infused letter sent to a German prisoner.

In the past years, new psychoactive substances (NPS) started circulating in prisons, leading to health risks and challenges for the criminal justice system. Seizures of papers and cards impregnated with synthetic cannabinoid (SCs) have been reported. In November 2021, a letter suspected to be drug-infused was sent from a German prison to this laboratory. Toxicological analyses were performed by means of gas chromatography-mass spectrometry (GC-MS) for drug screening and liquid chromatography-tandem mass spectrometry (LC-MS/MS) as well as high-performance (HP) LC with diode-array detection (DAD) for semi-quantification of the compounds. The novel synthetic opioid (NSO) AP-237 was detected on the letter, with an estimated concentration of 1.2 μg/cm 2 , together with the SCs MDMB-4en-PINACA (77 μg/cm 2 ) and 5F-ADB (6.5 μg/cm 2 ). To the best of the authors' knowledge, this is the first time an NSO was detected on a drug-infused paper seized in a prison. Highly potent NSOs could easily be dissolved in organic solvents to produce impregnated papers and textiles, and this might represent a serious threat to the health of people in prison. Given the inhomogeneity in drug concentrations, health risks might in particular arise from the consumption of highly concentrated areas of the paper-so-called "hot spots"-especially when highly potent NSOs are used for infusion. Laboratories engaged in analyzing such impregnated papers should be aware of the potential presence of NSOs and adapt the respective methods accordingly.