DrogoFinder: An open-source graphical user interface for the identification of illicit drugs using infrared spectroscopy

The development of Free and Open-Source Software (FOSS) is being increasingly recognized as an indispensable resource for the development, validation, and replication of analytical methodologies and tools. In this context, the use of Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy for the in-situ identification of drugs requires software for the treatment of spectroscopic data, including spectral quality controls, the subtraction of possible excipients, and the comparison with well-defined libraries that can be complex and limits its application on the field analysis by non-expert users. Here we describe a user-friendly FOSS for drug identification that can be operated in an intuitive way, including automatic features such as i) quality controls that warn the user from possible technical problems during spectrum acquisition (e.g. water vapour, contaminated background), ii) the subtraction of the contribution of excipients and other substances present on the sample, and iii) the creation of custom and updated cloud-based libraries to deal with the great number of new psychoactive substances (NPS) that are constantly being developed and introduced for their consume. The proposed application was tested by expert and non-expert users with spectra from 42 drug samples measured in situ in a music festival and 39 seized samples measured in a laboratory. Non-expert users were able to flag technical problems in the spectra and to perform excipient subtractions automatically, obtaining drug identifications that matched those ones obtained by reference methods and dedicated commercial software. We share both, the code, and a standalone Windows app to reach worldwide users and scientists interested in the identification of drugs.