Organizing co mmittee

DEGREE OF DEACETYLATION OF CHITOSAN PRODUCED FROM 
Artemia parthenogenetica CYST OF THE ARAL SEA 
 
B.P. Karlybaeva, G.E. Berdimbetova, I.J. Erinyazova, P.M. Kudainazarova 
 
Karakalpak Research Institute of Natural Sciences, Karakalpak branch of the Academy 
of Sciences of Uzbekistan, Karakalpakstan
 
Chitin is a linear aminopolysaccharide consisting of 
N
-acetyl-2-amino-2-deoxy-
D
-
glycopyranose units. Chitosan (CH) is formed by N-deacetylation of the chitin 
molecule. Usually, completely deacetylated chitosan does not exist in nature. The 
degree of deacetylation (DDA) chitosan is equal to the ratio of the number of 
glucosamine units (m) to the total number of monomer units in the polysaccharide 
molecule. 
The DDA of 
CH
is an important factor that not only determines the mole 
fraction of deacetylated units in its polymer chain, but also strongly affects its solubility, 
viscosity, ion exchange capacity, flocculation ability, and amino acid reaction. 
There are a number of methods for determining the degree of 
chitosan
deacetylation, 
including: methods of infrared (IR), ultraviolet (UV), nuclear magnetic resonance 
(NMR) spectroscopies, potentiometric and conductometric titrations can also be 
determined using elemental analysis and many other methods. It should be noted that 
NMR is a more advanced method for determining DDA of 
CH
. Only the cost of this 
device, as well as the reagents required for sample preparation, limit its use. And such 
methods as acid-base, potentiometric and conductometric titration methods are 
economically more accessible for the determination of DDA of chitosan. 
The purpose of this work is to determine the degree of deacetylation of 
chitosan
obtained 
from cysts of Artemia parthenogenetica of the Aral Sea by conductometric titration. 
The DD chitosan was determined by conductometric titration using an EC 215 instrument 
(HANNA Instruments, Germany). 
For this, 0.2 g (200 mg) of chitosan was dissolved in 20 ml 
of 0.1 N HCl solution. The resulting solution was titrated with 0.5 M NaOH solution, adding 
0.2 ml every 30 seconds with constant stirring. The amount of NaOH required for titration of 
the acid bound to amino groups was determined from the graph of the dependence of the 
electrical conductivity of the solution on the volume of NaOH. 
(а) 
(b) 
Fig.1. Conductometric titration curve of a blank solution of 0.1 N HCl and 0.5 M NaOH 
(a) and CH solution (b) 
The first inflection of the titration curve corresponds to an excess amount of 
hydrochloric acid, and the second one corresponds to the concentration of amino groups 
in a sample of chitosan. The calculation of DDA was carried out according to the 
formula: 
where m is the mass of chitosan in a sample, g; С
NaOH
– exact concentration of NaOH
 
solution, 
mol/dm3; V
NaOH
- volume of NaOH solution used for titration of amino groups, cm
3
; 203.2; 42.0; one 
hundred; 1000 - conversion factors.
Thus, according to the results of conductometric titration, it was determined that the 
DDA of the obtained chitosan from the cyst of 
Artemia parthenogenetica
is 84%.