Preparation of Thin Sections for Fourier Transform-Infrared Microscopy: a New Embedding Medium for Cellulosic Samples

Fourier Transform-Infrared [FT-IR] microscopy is a combination of instrumentation from which information can be derived about the structure and composition of materials; however, it presents unique problems for sample preparation. Traditional methods of preparing fiber cross sections employ embedding media such as methacrylates, epoxides and polyvinyl alcohols, all of which have groups in common with the cellulose molecule, and absorb in the same regions of the IR spectrum. Therefore, a new embedding method employing polystyrene has been developed for the preparation of cross and longitudinal sections of cellulosic fibers. Although polystyrene is a strong IR absorbing material, it can be completely removed from specimens prior to analysis. In addition, FT-IR spectra of cross sections have better resolution than conventional preparation methods employing ground samples prepared in a KBr disk.