Origin identification of homemade pepper spray by multivariate data analysis of chemical attribution signatures.

Riot control agents such as pepper sprays can be misused for antagonistic and criminal purposes. Several web-pages and YouTube videos are available describing how to make homemade pepper spray. In this study, we investigated whether it was possible to identify the origin of homemade pepper sprays based on chemical attribution signatures from thirteen different types of chili acquired from six different vendors analyzed by GC-MS. The results showed that it was possible to differentiate chili based on species, chili type and vendor using OPLS-DA. Application of an external test set of chilies acquired and extracted one year later than development of the models resulted in correct classification in all models. The models displayed high predictability, suggesting their use for prediction of the identity and origin of seized homemade pepper sprays.