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. H-1-NMR taken in 2% DCl solutions. at 70 degrees 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 degrees C (the standard NMR probe temperature) with 90 degrees pulses. Routine conditions allowing DA determinations in less than 3.5 min of NMR time per sample are described. (C) 2005 Elsevier Ltd. All rights reserved.