NONDESTRUCTIVE DISCRIMINATION OF BIOLOGICAL-MATERIALS BY NEAR-INFRARED FOURIER-TRANSFORM RAMAN-SPECTROSCOPY AND CHEMOMETRICS - DISCRIMINATION AMONG HARD AND SOFT IVORIES OF AFRICAN ELEPHANTS AND MAMMOTH TUSKS AND PREDICTION OF SPECIFIC-GRAVITY OF THE IVORIES

This paper demonstrates the usefulness of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy and chemometrics in nondestructive d iscrimination of biological materials. The discrimination among three kinds of materials-hard ivories, soft ivories, and mammoth tusks-has b een investigated as an example. NIR (1064-nm) excited FT-Raman spectra were measured in situ for these materials, and principal component an alysis (PCA) of the obtained spectra was carried out over the 1800-400 -cm(-1) region. The two kinds of ivories are clearly discriminated fro m one another on the basis of a one-factor plot. It was found that tre atment of the Raman data by multiplicative scatter correction (MSC) gr eatly improves the ability to discriminate. Principal component weight loadings show that the discrimination relies upon the ratio of collag en and hydroxyapatite included in two kinds of ivories. The discrimina tion among the hard and soft ivories and mammoth tasks was made by a t hree-factor plot for FT-Raman spectra after the MSC treatments. Partia l least-squares regression (PLSR) enabled us to make a calibration mod el which predicts the specific gravity of the hard and soft ivories.