Investigation of the Damage on the Outermost Hair Surface Using ToF-SIMS and XPS

The study investigated hair damage by analyzing changes in fatty acids and protein fragment ions using ToF-SIMS and XPS. It found that the intensity of the fragment ion m/z 76, related to cystine and cysteine in hair keratin, decreased with hair damage, indicating oxidative cleavage of thioester and disulfide bonds. Additionally, 18-methyleicosanoic acid, a major fatty acid component, decreased rapidly during three bleaching processes, correlating with the decrease in m/z 76. This suggested that oxidative cleavage of thioester bonds in fatty acids was a significant change caused by bleaching.