Oxidized reducing ends in celluloses: Quantitative profiling relative to molar mass distribution by fluorescence...

Area of Science:

• Cellulose chemistry
• Analytical chemistry
• Polymer science

Background:

• Cellulosic materials have diverse applications, and understanding their oxidation state is crucial.
• Quantifying oxidized reducing end groups (REGs) provides insights into cellulose degradation and modification.
• Existing methods for REG quantification may lack specificity or require complex procedures.

Purpose of the Study:

• To develop and optimize a highly selective fluorescence labeling method for quantifying C1-oxidized REGs in cellulosic materials.
• To integrate this method with size exclusion chromatography for simultaneous molecular weight distribution analysis.
• To demonstrate the method's applicability to chemically and enzymatically oxidized cellulose samples.

Main Methods:

• Optimization of a heterogeneous fluorescence derivatization process using N-(1-naphthyl)ethylenediamine in N-methyl-2-pyrrolidone.
• Selective reduction of keto/aldehyde groups and blocking of non-C1 carboxyl groups prior to labeling.
• Coupling of the optimized method with size exclusion chromatography (DMAc/LiCl) and multi-detector systems (fluorescence, MALS, RI).

Main Results:

• A robust and selective method for fluorescence labeling of C1-oxidized REGs was established.
• The method allows for the detailed profiling of C1-oxidized REGs relative to molecular weight distribution.
• Successful application of the method to quantify C1-oxidized REGs in cellulose samples subjected to Pinnick oxidation and enzymatic treatment.

Conclusions:

• The developed fluorescence labeling and SEC-MALS/RI method provides accurate quantification of C1-oxidized REGs in cellulose.
• This analytical approach is valuable for characterizing cellulose materials, particularly after oxidative modifications.
• The optimized protocol enhances selectivity and practical applicability for cellulose research and industry.