The classification of cocaine seized according to its form was
possible using ATR–FTIR spectra and chemometrics. Unsupervised
multivariate techniques (HCA and PCA) separated samples of
cocaine seized in salt and base correctly for all samples. The HCA
also enabled the identification of samples with the possibility of
the same refining process or the same adulteration pattern in drug
trafficking processing, due to the similarity of their spectra. This
information is extremely important for judicially prove the
existence of cocaine trafficking networks and supply the police
intelligence for combating drug trafficking. Through the analysis of
mixtures and the PCA, it was possible to qualitatively predict the
composition of the samples and to obtain a profile of adulteration
of cocaine seized. The two supervised methods correctly classified
all samples between base and salt cocaine and SVM-DA showed a
better fit to the data compared to PLS-DA. The salt cocaine seized in
State of Rio Grande do Sul, Brazil had high purity and, in relation to
the pharmaceutical products studied, is not adulterated with
phenacetin. The base cocaine is exclusively adulterated with
phenacetin, among the pharmaceutical products studied, and it is
less pure than the salt cocaine.