Validación de una técnica potenciométrica para determinar el grado de desacetilación de la quitosana / Validation of potentiometric method to determine the degree of deacetylation of chitosan

ABSTRACT

The purpose of this study was to validate, in accordance with international standards, a potentiometric method todetermine the degree of deacetylation of chitosan samples derived from lobster chitin. To ensure a complete reactionbetween the analyte and the HCl solution, the samples were heated to temperatures of up to 60ºC. The change in pHand the methyl orange method, as a visual indicator were used to detect the fi rst infl ection point. The transition intervalfell within the narrow pH acid range of 2 to 4. From an analytical point of view, no interference was observed onthe potentiometric curve in the absence of the analyte, thus showing that the method was suffi ciently selective. For thedetermination of the percentage of free amino groups, the method proved to be linear within the 10.0 to 15.0 mg/mL range, as well as precise and exact (AU)