Chromophores in cellulosics, VI. First isolation and identification of residual chromophores from aged cotton linters

In the present work, aged cotton linters have been analyzed for their chromophore content according to the CRI (“chromophore release & identification”) method. Despite the very low contents in the ppb range, nine chromophores have been unambiguously identified, which makes this account the first one on defined chromophoric structures isolated from cotton. A common feature of the chromophores are 2-hydroxy-[1,4]benzoquinone, 2-hydroxyacetophenone and 5,8-dihydroxynaphthoquinone moieties, which resemble chromophoric structures found in other cellulosic substrates, such as bleached pulps or fibers. The finding of these compounds in lignin-free cotton linters confirms the previous hypothesis that those chromophores are formed from (oxidized) carbohydrate structures rather than from lignin fragments.