Characterization and quantification of chitosan extracted from nacre of the abalone Haliotis tuberculata and the oyster Pinctada maxima

This study was performed to characterize and quantify chitosan by simple ph ysicochemical methods (infrared spectroscopy and potentiometric measurement s). These procedures were validated with well-characterized chitosan before being used to investigate chitosan in nacre of the abalone Haliotis tuberc ulata and of the giant oyster Pinctada maxima. Potentiometric study reveale d a chitosan extract from the nacre of H. tuberculata with a degree of deac etylation of around 88% and an intrinsic pK of 6.5. According to infrared a nd potentiometric data, a low yield (eta) of extraction was calculated (eta = 0.064%). For experiments performed on the nacre of P. maxima, and in spi te of more stringent deacetylation conditions, results suggested that a chi tin-protein complex (eta = 0.053%) was isolated rather than chitosan.