75 years of forensic profiling: A critical review.

The interest in characterization of drugs abused started in 1948 with the aim of determining the origin of opium. After 75 years there is still a great interest in this approach, called geo-profiling, chemical or forensic profiling in the following decades. Recently chemical attribution signatures (CAS) were proposed by the authors who studied "synthesis precursors and byproducts, impurities, degradation products, and metabolites in various biological matrices" of fentanyl. Forensic profiling evolved during these decades: new analytical approaches were tested and it was applied to more and more products, which threaten the health and security of citizens worldwide. In substances of natural origins (e.g. opium, cannabis and cocaine), it is possible to exploit the great variability of both elements and organic chemical compounds and to study chemical compounds such as reagents and solvents, by-products, and cutting agents used in the production chain. Profiles can be used to classify products from different seizures into groups of similar samples (tactical intelligence) or to determine the origin of samples (strategic intelligence). Chromatographic approaches coupled to mass spectrometry are very common to determine organic profiles, while elemental profiles are obtained by nuclear activation analysis, inductively coupled plasma mass spectrometry or ion beam analysis. A very important role in the field is played by isotope ratio analysis. Approaches to obtain forensic profiles are available also for chemical warfare agents, explosives, illegal medicines, doping agents, supplements, food. Chemometrics can be particularly useful to establish the authenticity of products and for the interpretation of large amount of forensic data. The future of forensic profiling is a challenge for forensic sciences. Organized crime is involved in the manufacturing of a large number of illegal products and forensic profiling is a very powerful tool to support the health of citizens and the administration of justice worldwide.