Optimal routine conditions for the determination of the degree of acetylation of chitosan by 1H-NMR

Chitosan applications and properties mostly depend on its degree of acetylation, so methods that allow its accurate determination are needed. 1H-NMR taken in 2% DCl solutions at 70 °C is usually employed for that purpose but suffers from long experimental times. Here, it is demonstrated that this time can be dramatically reduced more than six-fold by simply performing the 1H-NMR experiment at 27 °C (the standard NMR probe temperature) with 90° pulses. Routine conditions allowing DA determinations in less than 3.5 min of NMR time per sample are described.