Paper spray ionization mass spectrometry applied to forensic chemistry – drugs of abuse, inks and questioned documents

Abstract

With the advent of a new family of ionization techniques, ambient mass spectrometry (or ambient MS) was introduced as a simple way of generating ions in MS. Among them, the paper spray ionization (PS-MS) technique has demonstrated to be versatile to solve numerous problems in many areas of science. In this work, the PS-MS technique in the positive ionization mode (PS(+)-MS) was applied in two subareas of forensic chemistry: drugs of abuse and documentoscopy. In the first, the PS(+)MS technique was applied to obtain the chemical profiles of illicit drugs such as blotter papers containing 25I-NBOMe, extracts and leaves of natural cannabinoids (Δ⁹-tetrahydrocannabinol) and synthetic cannabinoids (naphthalen-1-yl-(1-butylindol-3-yl)methanone, (JWH-073); n-(adamantan-1-yl)-1-(4-fluorobutyl)-1H-indazole-3-carboxamide (5F-AKB48); 4-methyl-1-naphthyl-1-pentylindol-3-yl-methanone (JWH-122); 2-(2-methoxyphenyl)-1-(1-pentylindol-3-yl)ethanone (JWH-250); and 4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-210)) as well as to determine the authenticity in weight-loss herbal samples. Finally, an analytical method has been developed to quantify eight illicit drugs (3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), meta-chlorophenylpiperazine (m-CPP), methamphetamine (MA), cocaine, lysergic acid diethylamide (LSD), and dimethoxybromoamphetamine (DOB)) where their limit-of-detection ranged from 0.17 to 1 ppb, with linearity R² > 0.99. The performance of the PS(+)-MS technique was also compared to other ionization sources: leaf spray mass spectrometry (LS-MS), and electrospray ionization mass spectrometry (ESI-MS). In the second part of this study, the PS(+)MS technique was successfully able to obtain the chemical profiles of different commercial blue pens. The relative intensity (RII₃₇₂) of the methylene blue dye was monitored to discriminate crossings of traces, and to date questioned documents. The chemical profile of the second generation of Brazilian banknotes (R$, reais) was also explored. In general, the PS(+)-MS technique was proved to be an excellent analytical tool in forensic chemistry, acting like a “Swiss army knife”.