Evaluating the selectivity of colorimetric test (Fast Blue BB salt) for the cannabinoids identification in marijuana street samples by UV-Vis, TLC, ESI(+)FT-ICR MS and ESI(+)MS/MS

Marijuana is one of the most marketed illicit drugs in the world. Originated from Cannabis sativa L, Delta(9)-tetrahydrocannabinol (or Delta(9)-THC) is proscribed in Brazil by the law number 11.343 from August 23rd of 2006 as well as its isomers, salts, ethers and esters. However, Delta(9)-THC is the main responsible for the hallucinogenic effects of the plant. The principal screening test used by the Brazilian Forensic Police is a colorimetric test called Fast Blue B or BB salt, in which the development of a reddish color in a basic medium indicates the presence of cannabinoids such as Delta(9)-THC, cannabinol (CBN) and/or cannabidiol (CBD). However, a better understanding of this chemical reaction is required. In this work, the products of the colorimetric test were identified by positive-ion mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI(+)FT-ICR MS), collision-induced dissociation (CID) experiments or ESI(+)MS/MS, ultraviolet-visible (UV-Vis) spectroscopy and thin layer chromatography (TLC). A chemical structure was proposed for the product of the reaction (m/z 626) formed by Fast Blue BB salt (4-amino-2,5-diethoxybenzanilide diazotated zinc double salt) and Delta(9)-THC molecule. Besides, the selectivity of the colorimetric test was evaluated in presence of interferences from other plants such as Jacaranda decurrens Cham and Paullinia cupana Kunth. (C) 2016 Elsevier B.V. All rights reserved.