FT-IR MICROSPECTROSCOPIC IMAGING OF FLAX (LINUM-USITATISSIMUM L.) STEMS

Fourier transform infrared (FT-IR) microspectroscopy was used to image and subsequently produce maps of the distribution chemical components in flax stem tissue. Cross-sections of two flax cultivars, Ariane and Natasja, were examined. The infrared maps produced were keyed to the visible images of the samples, thus permitting superimposition of chem ical composition onto anatomical structure. The functional group frequ encies utilized to produce chemical maps were based on their diagnosti c capability for indicating each component to the exclusion of others in the matrix, by comparison of the spectra of ''pure'' components. Wa xes were best indicated by a sharp shoulder at 2850 cm(-1) and appeare d primarily in the cuticular and epidermal tissues. Pectins gave a ban d ca. 1615 cm(-1) for the Ca2+ salt form that was primarily detected i n tissue surrounding the fiber bundles. Cellulose was the strongest co ntributor to the band located at ca. 1335 cm(-1) that showed its great est intensity in the fiber cells. Aromatic compounds were indicated mo st readily by the band at 1510 cm(-1) and were located primarily in th e core tissue. Acetyl groups, likely associated with hemicellulosic po lysaccharides, were indicated by a band centered at 1250 cm(-1) and fo und within the fibers and core tissue.