Potentiometric determination of degree of chitosan
deacetylation
Michał Kaczmarek
Keywords: chitosan deacetylation degree, potentiometric titration,
equipment required:
 Glass electrode with EMF (electromotive force) meter
 Automatic burette
required reagents:
 100 ml 1 % solution of hydrochloric acid
 20 ml Anhydrous hydrochloric acid
 100 ml 1,4-dioxide
 1 M perchloric acid HClO4
execution time: from 10 min
Procedure Description:
Measurement of the degree of deacetylation of chitosan is based on the measurement of the
electromotive force, which is changed by the addition of further portions of titrating substance. As a
result of the addition of perchloric acid HClO4, NH2 groups are neutralized. This reaction resulting in
the observed change in the measured EMF.
Procedure:
1. Dissolve sample of chitosan ranging from 0,10 g to 0,15 g in 100 ml 1% solution of
hydrochloric acid.
2. After 30 minutes continuous stirring take 20 ml of prepared solution and place into the
measuring dish
3. Add 20 ml anhydrous hydrochloric acid and 100 ml 1,4- dioxide.
4. Titrate solution using 0,1 M perchloric acid HClO4 using automatic burette.
Degree of deacetylation (DA) of chitosan was calculated using formula:
𝑆𝐷 =
80,502 × 𝑛 × 𝑣
× 100%
𝑚
v – amount of HClO4 solution used to obtain neutralization point [ml]
n – titre of HClO4 solution
m – sample weight