Determination of Carbonyl Functions in Cellulosic Substrates

The reliable and accurate determination of oxidized functionalities in cellulosic substrates still represents a largely unsolved problem in cellulose chemistry. Aldehyde and keto structures are “hot spots” along the cellulose chain, where further chain cleavage might occur. Carbonyls are also relevant for processes such as yellowing or aging. Conventional approaches (copper number, oxime or cyanohydrin method) provide sum parameters only and suffer from limited comparability. In our approach fluorescence labeling was chosen. Pulps are treated with a highly selective fluorescence label and are subsequently analyzed by size exclusion chromatography. The method is applied as pre-column derivatization and allows the measurement of carbonyl profiles (plots DS vs. MW). Thus, the total carbonyl content and the differential mass distribution of pulps can be determined. Practical aspects of the newly developed method, a comparison of the approach to conventional methods, and different applications demonstrating the general scope of the method will be presented.