Molecular weight of chitin

The molecular weight of chitosan is another important property that determines its suitability for a particular application. It determines the viscosity of its solution and the strength of chitosan fiber and film. The molecular weight of chitin and chitosan depends on its source and deacetylation conditions [time, temperature, and concentration of NaOH], respectively [1, 4]. Molecular weight of chitosan determined by various methods such as viscometry [28], gel permeation chromatography [29] and light scattering spectrophotometry [30]. 

The main methods used to determine the molecular weight of chitin and chitosan are similar to those used for any polymer, namely, viscosimetry, light scattering, gel permeation chromatography, osmometry and sedimentation equilibrium by ultracentrifugation. The first three are briefly discussed in the following subsections since they are the most employed techniques. 

The other area of development that would benefit researchers is the availability of several molecular weights of chitin and chitosan produced under the same stringent production criteria. 

The molecular weights of chitin heparinoids were estimated from viscosity measurements with a Ubbelohde-type viscometer and using the viscosity equation proposed for heparin [26]. 

Qin, Y., Lu, X., Sun, N. and Rogers, R.D. (2010) Dissolution or extraction of crustacean shells using ionic liquids to obtain high molecular weight purified chitin and direct production of chitin film and fibers. Green Chemistry, 12,968-971. 

Chen, R.H. and Chen, J.S. 2000. Changes of polydispersity and limiting molecular weight of ultrasound-treated chitosan. Adv. Chitin Sci. 4 361-366. 

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