The use of Fourier transform infra-red spectroscopy in the study of the surface chemistry of hair fibres

Human hair keratin is susceptible to damage by both chemical and physical agencies. Oxidative damage can now be assessed by the use of Fourier transform infra-red (FTIR) spectroscopy.
Analysis may be performed using the following techniques; diffuse reflectance, attenuated total reflectance and microspectrophotometry. This latter technique is made possible by the coupling of a research grade microscope to the optical bench of the FTIR spectrometer.
The computing power necessary to operate the FTIR allows data to be mathematically manipulated. Derivative spectra obtained in this manner allow small peaks obscured by the close proximity of large peaks to be resolved.
Analysis of single fibres treated with hydrogen peroxide or metabisulphite solutions showed the formation of cysteic acid and cysteine-S-sulphonate respectively.
Second order derivative spectroscopy allowed a profile of the oxidative damage from the root to tip of naturally weathered hair to be constructed.