Another script that I wrote to determine degrees of subsitution (DS) on modified cellulose was based on 31P NMR analysis.
Chemical modified celluloses are derivatised as phosphite esters (Fig). Those phosphite esters are quantified against an internal standard to allow for the determination of the ‘available hydroxyls’ per mass unit of sample. Based on the molecular weight of the additional functionality and the available hydroxyls value the DS can be calculated.
This script and the method development were published in the journal Analytical Methods.