More and more events, such as the summer music festivals, are considering the
possibilities for implementing on-site testing of psychoactive drugs in the context of
prevention and harm reduction. Although the on-site identification is already
implemented by plenty of drug checking services, the required rapid quantitative
dosing of the composition of illicit substances is still a missing aspect for a successful
harm reduction strategy at events. In this paper, an approach is presented to identify
white powders as amphetamine, cocaine, ketamine or others and to estimate the
purity of the amphetamine, cocaine and ketamine samples using spectroscopic
techniques hyphenated with partial least squares (PLS) modelling. For identification
purposes, it was observed that mid-infrared spectroscopy hyphenated with
PLS-discriminant analysis allowed the distinction between amphetamine, cocaine,
ketamine and other samples and this with a correct classification rate of 93.1% for an
external test set. For quantitative estimation, near-infrared spectroscopy was more
performant and allowed the estimation of the dosage/purity of the amphetamine,
cocaine and ketamine samples with an error of more or less 10% w/w. An easily
applicable, practical and cost-effective approach for on-site characterisation of the
majority of the psychoactive samples encountered in Belgian nightlife settings based
on IR spectroscopy was proposed.
