Chitin fractionation and characterization in N,N-dimethylacetamide/lithium chloride solvent system

A detailed study of the interaction of chitin molecular species with the solvent system N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl) allowed the development of a new method for chitin fractionation by coacervate extraction. The controlled increase of the extracting power of the solvent was carried out using slight modification of the solvent composition. Partial extractions of molecular species were done between coacervation and complete dissolution limits using different mixtures of DMAc/LiCl of increasing extracting power. Fractions were characterized in DMAc/LiCl 5% (w/w) by viscometry and size exclusion chromatography with refractive index and multi-angle laser light scattering detectors. Fractions obtained by coacervate extraction range from 80,000 to 710,000 g mol−1 with polydispersity index between 1.28 and 1.44. The Mark–Houwink–Sakurada equation constants a and K for chitin in DMAc/LiCl 5% (w/w) were found to be 0.95 and 7.6×10−5 dl g−1, respectively.