The formulae of the deacetylating degree of chitosan are given by: y =203.195 x /(16.022 62+0.420 37 x),y =20.202 1 x /(16.022 62+0.041 794 x )(theoretical equations) ; y =0.015 53+ 12.645 34 x - 0.314 47 x ²+0.005 46 x ³,
y =0.015 53+1.257 22 x -0.003 11 x ²+5 362 65×10 ^-6 x ³ (fit equations),
where y is degree of deacetylation, and x is mass fraction of amino in the
first equation or percent of free amino of chitosan in the second . The coefficient of determination is 1 and standard deviation is 0.00663. The calculated valued of degree of deacetylation reflects the deacetylating degree of chitosan molecular accurately.