Journal Published Online: 01 March 2002
Volume 47, Issue 2

Classification of Narcotics in Solid Mixtures Using Principal Component Analysis and Raman Spectroscopy



Eighty-five solid samples consisting of illegal narcotics diluted with several different materials were analyzed by near-infrared (785 nm excitation) Raman spectroscopy. Principal Component Analysis (PCA) was employed to classify the samples according to narcotic type. The best sample discrimination was obtained by using the first derivative of the Raman spectra. Furthermore, restricting the spectral variables for PCA to 2 or 3% of the original spectral data according to the most intense peaks in the Raman spectrum of the pure narcotic resulted in a rapid discrimination method for classifying samples according to narcotic type. This method allows for the easy discrimination between cocaine, heroin, and MDMA mixtures even when the Raman spectra are complex or very similar. This approach of restricting the spectral variables also decreases the computational time by a factor of 30 (compared to the complete spectrum), making the methodology attractive for rapid automatic classification and identification of suspect materials.

Author Information

Ryder, AG
National University of Ireland, Galway, Galway, Ireland
Pages: 10
Price: $25.00
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Stock #: JFS15244J
ISSN: 0022-1198
DOI: 10.1520/JFS15244J