Sensitized Photooxidation of Wool by Fluorescent Whitening Agents. A Direct Spectral Study

Abstract—A fluorescence spectral study has been made of the photochemical behaviour of two types of fluorescent whitening agents, a naphthotriazolylstilbene and a bistriazinylaminostilbene, in single fibres of wool. The photodecomposition of each molecule of the naphthotriazolylstilbene is accompanied initially by the photooxidation of up to 7 residues of trp in the fibre. Amino acid analyses show that his and met residues are also photooxidized. Inhibition of the photooxidation of these amino acids by sodium azide suggests that singlet oxygen is involved in the reaction.