The Use of FTIR to Investigate Modifications to Wool Treated with Sodium Sulphite and Cationic Protein Hydrolysate

Wool was treated with sodium sulphite and amphiphillic cationic proten hydrolysate mixtures for different times and temperatures. The surface chemical modifications were followed using Fourier transform infra-red spectroscopy coupled with the attenuated total internal reflectance sampling technique. The resolution of the infra-red bands in the wool spectrum was improved by differentiation to the second-order derivative. Absorbance bands in the 1300 – 900 cm-1 region were observed to change as a function of both time and temperature. Bunte salt was the main product formed from cystine, and it was measured by comparing the intensity of the Bunte salt band with the intensity of the peptide band (amide 3) in the second-order derivative spectrum. It was possible to detect dehydroalanine formation and sorption of the amphiphilic cationic protein hydrolysate in the spectrum of treated wool