Based on quantitative, group-specific fluorescence labelling of celluloses with carbazole-9-carboxylic acid [2-(2-aminooxyethoxy)-ethoxy]-amide (CCOA), which is fully compatible with SEC-MALLS/RI analysis, a profiling of oxidized functionalities (keto and aldehyde groups) relative to the molar mass distribution is performed (Röhrling et al. 2002a/b, Potthast et al. 2003).

The fluorescence label reacts selectively with all aldehyde and keto groups present along the cellulose chain, including the hemiacetal structures of the reducing ends. If required, data can be correlated with the theoretical amount of reducing ends as calculated from the number average molar mass data, providing the degree of along-chain oxidation. The labelled pulp is dissolved in DMAc/LiCl and analyzed by a SEC-MALLS/fluorescence/RI combination. Importantly, the fluorescence label does not interfere with MALLS detection.

The method provides absolute numbers of carbonyl concentrations with a high precision and sensitivity besides the molar mass dependent profiles. CCOA analysis can be used to judge changes of pulps upon industrial treatments,  such as oxidations in bleaching, alkalinization, e-beam treatment, periodate and TEMPO oxidation, to name but a few. In addition, it provides valuable information in aging studies of different kinds, in conservation treatments, or it can be used to judge oxidative damage of (historic or recent) cellulosic materials. Please refer to the publication list in CF ALICE for numerous application examples.

Sample amount generally required: 50-100 mg (see above at SEC measurements).

Schematic of fluorescence labelling with CCOA (left). Carbonyl group profiles for periodate oxidation of cellulose with different degrees of severity (right).

References

Röhrling, J.; Potthast, A.; Rosenau, T.; Lange, T.; Ebner, G.; Sixta, H.; Kosma, P.,
A novel method for the determination of carbonyl groups in cellulosics by fluorescence labeling. 1. Method development.
Biomacromolecules 2002a, 3 (5), 959-968.

Röhrling, J.; Potthast, A.; Rosenau, T.; Lange, T.; Borgards, A.; Sixta, H.; Kosma, P.,
A novel method for the determination of carbonyl groups in cellulosics by fluorescence labeling. 2. Validation and applications.
Biomacromolecules 2002b, 3 (5), 969-975.

Potthast, A.; Röhrling, J.; Rosenau, T.; Borgards, A.; Sixta, H.; Kosma, P.,
A novel method for the determination of carbonyl groups in cellulosics by fluorescence labeling. 3. Monitoring oxidative processes.
Biomacromolecules 2003, 4 (3), 743-749.