Comparisons of the Fourier Transform Infrared Spectra of cashmere, guard hair, wool and other animal fibres

Fourier Transform Infrared Spectroscopy (FTIR), identifies chemical bands related to chemical bonds including amino acid groups. The potential for FTIR to differentiate animal fibres from different origins was investigated using cashmere (Chinese, Australian, Iranian), wool (Chinese, Australian), bison wool, qiviut from Musk-ox, vicuña and guard hairs present in these raw fibre samples. Cashmere from a controlled nutrition experiment with known amino acid composition was included in the study. While the intensity of FTIR spectra were moderately correlated with the content of some of the amino acids in cashmere, this investigation did not detect any significant systematic effects of nutritional manipulation of cashmere goats on the FTIR spectra of their cashmere. Significant differences were detected in the intensity of FTIR spectra between cashmere and wool, cashmere from different origins, white and coloured cashmere, and between cashmere and hair. The FTIR spectra of cashmere and wool overlapped with those of bison, qiviut and vicuña. The intensity of FTIR spectra were not correlated with the mean fibre diameter of samples but the intensity of most spectra bands were positively correlated with the fibre curvature of the samples (r = 0.27–0.38). Based on these results it does not seem likely that FTIR spectra offer a reliable method to distinguish between pure cashmere and blends of cashmere with wool or other animal fibre for diagnostic tests to determine the fibre composition in finished textiles.