Uncertainties in depth determination and comparison of multivariate with univariate analysis in confocal Raman studies of a laminated polymer and skin.

Confocal Raman microscopy data are reported for a laminated polymer (Paramount) and for pigskin. The nature of the laminated structure of the polymer provides a useful test for evaluation of thickness distortions in confocal measurements in soft samples, which are found to be quite significant. The spatial variation in line profiles generated from univariate analyses with scores derived from factor loadings are consistent for both samples and provide distinct diagnostic markers for stratum corneum and epidermis regions of skin. Univariate analysis of the C-C stretching region of skin reveals a spatial dependence of chain conformational order. In addition, variations in keratin-containing areas of the stratum corneum are readily identified from area maps of the S-S stretching vibrations. These data indicate that confocal Raman imaging studies of molecular structure changes in particular regions of skin during pathological processes will prove quite valuable in dermatology.