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Ambient mass spectrometry has been demonstrated, via various proof-of-concept studies, to offer a powerful, rather universal, simple, fast, nondestructive, and robust tool in forensic chemistry, producing reliable evidence at the molecular level. Its nearly nondestructive nature also preserves the sample for further inquiries. This feature article demonstrates the applicability of ambient mass spectrometry in forensic chemistry and explains the challenges that need to be overcome for this technique to make the ultimate step from the academic world into forensic institutes worldwide. We anticipate that the many beneficial and matching figures of merit will bring forensic chemistry and ambient mass spectrometry to a long-term relationship, which is likely to get strongly consolidated over the years.

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Cocaine and crack cocaine are usually seized with a great diversity of adulterants, such as benzocaine, lidocaine, caffeine, and procaine. The forensic identification of cocaine in these drug mixtures is normally performed using colorimetric testing kits, but these tests may suffer from interferences providing false-positive or false-negatives. In this work, we describe the use of thin layer chromatography coupled to easy sonic-spray ambient ionization mass spectrometry (TLC/EASI-MS) for rapid and secure analysis of cocaine and crack cocaine. Fifteen cocaine samples were analyzed, and all of them revealed positive TLC/EASI-MS results for cocaine, but other drugs and adulterants were also detected such as lidocaine, caffeine, benzocaine, lactose, benzoylecgonine, and ecgonidine. False positives and false negatives, as judged by the TLC Rf values, were identified via on-spot characterization by EASI-MS. The TLC/EASI-MS combination seems therefore to provide an appropriate technique for secure forensic investigations of illicit drugs

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In this work, Raman hyperspectral imaging, in conjunction with independent component analysis, was employed as an analytical methodology to detect an ammonium nitrate fuel oil (ANFO) explosive in banknotes after an ATM explosion experiment. The proposed methodology allows for the identification of the ANFO explosive without sample preparation or destroying the sample, at quantities as small as 70μgcm. The explosive was identified following ICA data decomposition by the characteristic nitrate band at 1044cm. The use of Raman hyperspectral imaging and independent component analysis shows great potential for identifying forensic samples by providing chemical and spatial information.

Using desorption/ionization techniques such as easy ambient sonic-spray ionization mass spectrometry (EASI-MS), it is possible to analyze documents of Brazilian vehicles for authenticity, providing a chemical profile directly from the surface of each document. A method for the detection of counterfeit documents is described, and the falsification procedure is elucidated. Forty authentic and counterfeit documents were analyzed by both positive and negative ion modes, EASI(±)-MS. EASI(+)-MS results identified the presence of (bis(2-ethylhexyl)phthalate plasticizer and of dihexadecyldimethylammonium biocide in both types of documents. For EASI(-)-MS results, the 4-octyloxybenzoic acid additive ([M + H](+): m/z 249) is present only in counterfeit documents. It was also found that counterfeit vehicle documents are produced via Laserjet printers. Desorption/ionization techniques, such as EASI-MS, offer therefore, an intelligent way to characterize the counterfeiting method.

A layer-by-layer methodology was used for synthesizing CeO2/TiO2 and TiO2/CeO2 core–shell nanoparticles supported in Vycor glass pores. The layers were deposited by cerium- or titanium-based metalloorganic precursor decomposition. Sequential depositions promoted linear mass increases of the Vycor pieces and a linear decrease of both total pore size and total surface area, confirmed by N2 adsorption–desorption isotherms. Alternation in the metalloorganic precursors used results in the formation of spherelike nanoparticles (as observed by HRTEM) with core–shell architecture. Raman spectroscopy data showed that CeO2 is crystallized in the fluorite structure and TiO2 in the anatase phase. Shifts in the frequency and changes in line width of TiO2 Eg and CeO2 T2g Raman bands were used for monitoring changes in core size and shell thickness based on the quantum size effect and on the phonon confinement theory. Our results show that nanoparticle core sizes and the shell thicknesses can be tuned by changing the number of depositions used in the synthesis process.