The positions , , , and (symmetric) and cm (asymmetric CH stretching vibration) (Weissflog et al Littlejohn et al).The last two bands might be used to identify the crystallinity with the cuticle (Ho and Pemberton, Greene and Bain, Littlejohn et al) which differs in its inner (intracuticular wax) and outer parts (epicuticular wax; HerediaGuerrero et al).The univariate strategies i.e band integration is purchase BCTC extremely suitable for bands, that are not (or only slightly overlapping) with others, to provide a quickly overview.Nonetheless, this strategy is powerless relating to the splitting of your pure components or to separate changes in polymer amount from adjustments in polymer composition (side chains, crystallinity), which could go hand in hand.Additionally, resulting from the multicomponent nature of biological components we virtually often need to deal with overlapping bands, which can result in misleading conclusions or hide crucial adjustments.Necessity of Multivariate Procedures to Track Subtle Alterations in Lignin CompositionLignin is often a heterogeneous phenolic compound which complexity is still puzzling scientist around the world (Voxeur et al).The diversity of the monomer (oligomer) coupling and polymerization mechanisms tends to make the study of this polymer a tricky task (Boerjan et al).The breaking pathways of lignin (Mar et al) are of wonderful interest due to the fact it has been found as among the principal accountable for biomass recalcitrance in biofuel production (Batalha et al).Lignin varies involving species and also in between cellular forms inside the same treeplant (Campbell and Sederoff, Neutelings,).The potential of Raman imaging combined with multivariate solutions (e.g VCA) to differentiate also subtle changes in lignin composition was shown in spruce wood (Gierlinger,) and within this study on a Raman map of Arabidopsis such as xylem vessels and sclerenchyma fibers (Figure).The calculated endmember spectra proofed that PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21502231 the lignin within the cell corners gluing together the sclerenchyma fibers has far more similarity for the lignin inside the xylem vessel than in the fibers itself (EM).Apart from also changes inside the matrix have been observed depending if cells are connected in the vascular tissue (EM) or within the mechanical stabilizing sclerenchymatic tissue (EM).Specially the band at cm alterations between secondary cell walls of fibers and xylem and cell corners (Figure H).Frontiers in Chemistry www.frontiersin.orgFebruary Volume ArticlePrats Mateu et al.Raman Imaging of Waterproofing PolymersIn comparison to the reference spectra of milled wood lignin (MWL) in Figure , also a higher band at cm assigned for the aromatic ring conjugated CC bonds and for the CO group (of coniferaldehyde andor sinapaldehyde units in lignin; Agarwal and Ralph, Agarwal et al) was observed in Arabidopsis compared to MWL.Here extra similarity was found using the artificial polymerized DHP, which showed also a greater band at cm band and also the band at cm , assigned to coniferaldehydesinapaldehyde (Agarwal and Ralph, Agarwal et al), similarly pronounced like in EM spectra of Arabidopsis.The lignin most standard for the sclerenchyma fibers (Figure , EM), showed a larger band at and cm , which have been also clearly observed in MWL of beech (Figure , spectrum f) and are reported to become generally for syringyl units in lignin (Agarwal and Terashima, Sun et al).The presence of larger amounts of guaicyl lignin in vessel components and higher proportion of syringyl in fibers has been reported for wood samples (Saito et al) and is now pro.