Fluorescence labeling of C1-oxidized cellulose. Part 1: Method development

A novel method for fluorescence labeling and subsequent profiling of oxidized end groups along the molar mass distribution of cellulose has been developed. The notorious labeling reluctance of this group due to lactone (gluconolactone) formation was overcome by introducing amide-linked rather than ester-linked markers. A coupling method based on carbodiimide chemistry to bind the fluorophore N-(1-naphthyl)ethylenediamine (NED) was used and optimized with the model compound cellobionic acid towards appropriate reaction con-ditions and complete conversion. The reaction product, NED-labeled cellobionic acid (CBN), was obtained in 98 % yield, isolated by flash chromatography and comprehensively analytically characterized. CBN was used as a standard for HPLC quantification regarding reaction kinetics and stability analysis. The optimized labeling conditions were transferred to the heterogeneous derivatization of cellulose followed by GPC MALLS/IR/fluo-rescence analysis for molar mass-related profiling of oxidized reduced ends in cellulosic pulps.

Automated summary

A novel method for fluorescence labeling and profiling of oxidized end groups along the molar mass distribution of cellulose has been developed. The labeling reluctance due to lactone formation was overcome by introducing amide-linked markers. The optimized labeling conditions were transferred for molar mass-related profiling of oxidized reduced ends in cellulosic pulps.