On the rapid and non-destructive approach for barbiturates, benzodiazepines, and phenothiazines determination and differentiation using spectral combination analysis and chemometric methods

Abstract

The fast determination and differentiation of substance samples (tablets or powders) of medical drugs with high addiction potential by police or customs is an important forensic task. The sedative hypnotic drugs, due to their accessibility and low price, not only make some people from trying to use to becoming depended and addicted to them gradually, but also let some people be addicted to certain types of sedative hypnotic drugs due to the prolonged use. The attenuated total reflection (ATR)-Fourier transform infrared spectroscopy (FTIR) has been adopted with principal component analysis (KNN), Fisher discriminant analysis (FDA), and K nearest neighbor analysis (KNN) to develop a method for differentiating the target sedative hypnotic drugs of abuse. Automatic baseline correction, multivariate scatter correction, standard normal variate and Savitzky-Golay algorithm and the ATR correction were performed as pre-processing methods. PCA was used to reduce the infrared spectroscopy multi-dimensionality and extraction of feature variables. While FDA and KNN, the several supervised pattern recognition methods, were used as algorithms of constructing classifiers. The results showed that accuracy of combination spectral models was significantly higher than that of single models. The distinguishing ability of FDA model was superior to that of KNN model. First-second derivative model was better than that of other models in differentiating samples. All bands region model was more worthwhile than functional group or fingerprint region models. The optimal differentiation model was FDA model that based on all band region data of first-second derivative spectral combination. 13 different types of sedative hypnotic drugs were all differentiated exactly. The same kind of them from different places of origin were also distinguished accurately. The designed method represented a potentially rapid and non-destructive approach for determination and differentiation sedative hypnotic drugs.