Photodegradation of wool keratin: Part I. Vibrational spectroscopic studies

The photodegradation of wool keratin is a very complex process that is not well understood. In this work the techniques of Fourier transform Raman and attenuated total reflectance Fourier transform-infrared spectroscopies have been used to study wool samples irradiated in air using a variety of different sources. The spectra obtained from these samples have been compared with those obtained from wool treated with sodium bisulphite, a reagent well known to produce thiol and S-sulfonate groups. As an aid for spectral interpretation the Raman and infrared spectra of cystine and those of the sodium and potassium cysteine-S-sulfonates have also been obtained. The data suggest that there are two different photolytic reaction pathways involving the cystine residues which are dependent on the wavelength of the applied radiation.