This paper presents the investigation of fraud and of the theft of metal acquired by a Brazilian company from a Chinese supplier. Zinc ingots were transported by ship from China to the city of Londrina, in Paraná State, Brazil. However, they were substituted at some point during their journey, and replaced with bags containing fine crushed rock. In this case of a classic ‘substitution’ it was possible to use geological methods to investigate the crushed rock. As such, the mineralogical, petrological and isotope analysis showed the replaced rock did not originate from a Brazilian provenance. Therefore, the substitution possibly occurred before the cargo's arrival in Brazil. An inadequate chain of custody of the cargo, during transportation from Asia to Brazil, including the onward journey from Paranaguá to Londrina, is likely to have provided the opportunity for the material exchange to take place. Collaboration between the Brazilian Federal Police and geological experts based in academia enabled the crime to be investigated and solved.
New psychoactive substances (NPSs) have concerned authorities worldwide, and monitoring them has become increasingly complex. In addition to the frequent emergence of new chemical structures, the composition of adulterants has changed rapidly. Reliable reference data on NPS are not always available, and identifying them has become an operational problem. In this study, we evaluated the infrared spectral data of 68 seized samples suspected of containing a synthetic cathinone (N-ethylpentylone). We used quantum chemistry tools to simulate infrared spectra as a benchmark and obtained infrared spectra for different cathinones, structurally analogous amphetamines, and possible adulterants. We employed these in silico data to construct different chemometric models and investigated the internal and external validation and classification requirements of the models. We applied the best models to predict the classification of the experimental data, which showed that the seized samples did not have a well-defined profile. Infrared spectra alone did not allow N-ethylpentylone to be distinguished from other substances. This study enabled us to evaluate whether experimental, in silico, and applied statistical techniques help to promote forensic analysis for decision-making. The seized samples required in-depth treatment and evaluation so that they could be correctly analyzed for forensic purposes.
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