Cocaine profiling: Implementation of MCR-ALS for adulterant identification using ATR-FTIR in forensic analysis

Cocaine stands out due to its significant social problems stemming from trafficking, leading to increased violence and detrimental effects on the physical and mental health of its users. Brazil serves as a transit route for cocaine produced in Colombia, Peru, and Bolivia to Europe, with Paraná being a strategic region due to its border with Paraguay and the second-largest port in Brazil. Cocaine is gradually adulterated with cutting agents along the distribution chain, altering its chemical profile. Paradoxically, these components can create a unique chemical signature, enabling the tracing of the drug's origin and distribution routes. This study analysed 298 mid-infrared spectra of cocaine samples seized in Paraná and applied Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS) to identify and characterise the main adulterants and diluents present. MCR-ALS was chosen due to its ability to decompose overlapping spectra into individual component contributions, making it ideal for analysing complex mixtures. Five distinct chemical profiles were identified, and based on their spectral interpretation and the most reported adulterants and diluents in cocaine samples, the five components were defined as: cornstarch, cocaine, caffeine, sodium bicarbonate, and creatine. The concentration profiles of the components were clustered using Hierarchical Cluster Analysis, and seven profiles of cocaine samples were identified based on the amount of cocaine and the presence of adulterants and diluents. The MCR-ALS method proved effective in identifying cocaine cutting agents via ATR-FTIR, offering a fast and reliable approach for forensic analysis that can help to identify commercial routes.