Evaluation of Raman spectroscopy and application of chemometric methods for the differentiation of contemporary ivory specimens I: Elephant and mammalian species

Abstract

Specimens of mammoth, African and Asian ivory dentine, and other mammalian species were examined using Fourier-Transform (FT), conventional dispersive (confocal) and remote-sensing portable Raman spectroscopy, all with near-infrared laser excitation (1064 and 785 nm). FT-Raman spectroscopy produced the best quality spectra for differentiation purposes and the application of a fibre probe coupled to a portable Raman spectrometer has also been demonstrated and proposed for the in situ characterization of suspected contraband ivories at airports. In addition to the visual comparison of spectral features, chemometric methods are used to discriminate between African and Asian elephant dentine by analyzing normalized integrated band areas in ten selected wavenumber regions. Principal component analysis separates the spectra of both species into two well-defined groups based upon their organic and inorganic composition. By means of stepwise discriminant analysis almost 98% of the spectra are correctly classified to their species group memberships. Copyright © 2006 John Wiley & Sons, Ltd.