Identification and imaging of indole-3-carboxamide cannabinoids in hair using matrix-assisted laser-desorption/ionization mass spectrometry

Purpose Different kinds of new synthetic cannabinoids (SCs) have been continuously developed to evade drug monitoring. Segmental hair analysis offers a longer period for retrospective drug detection compared with blood or urine. In this study, matrix-assisted laser-desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometric imaging (MALDI-FT ICR MSI) was developed for direct identification and imaging of synthetic indole-3-carboxamide cannabinoids in hair samples using the positive ion mode. Methods The target SCs include N -(adamantan-1-yl)-1-pentyl-1 H -indole-3-carboxamide (APICA), N -(1-amino-3-methyl-1-oxobutan-2-yl)-1-(5-fluoropentyl)-1 H -indole-3-carboxamide (5F-AB-PICA), N -(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-pentyl-1 H -indazole-3-carboxamide (ADB-PINACA) and N -(1-amino -3,3-dimethyl-1-oxobutan-2-yl)-1-(5-fluoropentyl)-1 H -indole-3-carboxamide (5F-ADBICA). The MALDI-MS and MS/MS were first performed on the scraped hair soaked in a mixture of the four SCs after matrix sublimation. This method may provide a detection power for SCs to the 0.1 ng level per 2 cm hair. Target cannabinoids were identified by MS 1 and MS 2 . Matrix deposition methods including airbrush sprayer and sublimation were compared. Results The method was then applied in revealing the spatial distribution of APICA and 5F-ADBICA in real hair samples from two drug abusers by comparing MS 1 and MS 2 spectra. The metabolites of APICA and 5F-ADBICA were also presumed to be present in the positive hair samples. Furthermore, a comprehensive comparison between a MALDI-FT ICR MS and a MALDI time-of-flight–MS instrument was performed in detection-sensitivity and specificity for positive real samples. Conclusions The proposed method provides a powerful tool for drug supervision and forensic medicine analysis in a wide time window, and the sample amount required was also decreased.