METHOD FOR MEASURING DEGREE OF DEACETYLATION OF CHITOSAN FIBERS

摘要

A method for measuring a degree of deacetylation of chitosan fibers comprises the following steps: step 1. preparing a polyvinyl sulfate potassium (PVSK) solution, the concentration being C mol/L, performing calibration using a standard solution, and determining a correction coefficient f; step 2, preparing a toluidine blue (T.B) indicator, the mass percentage being 0.1%; step 3. weighing out a fixed weight, namely, m₁ grams, of chitosan fibers under test, placing the chitosan fibers in a conical flask, adding acid solutions that are suitable for dissolving chitosan fibers and have different mass percentages, preparing m grams of chitosan solutions having different mass percentages, performing stirring to thorough dissolution, after bubbles disappear, weighing out m₂ grams of the solution and adding the solution in a conical flask, adding 50 ml of deionized water, adding 3-4 drops of the T.B indicator, performing stirring on a magnetic stirrer while slowly adding drops of a PVSK titrant, where the titration endpoint is that the solution turns purple red from blue, the color stays unchanged within 30s, and a flocculent precipitate appears, and reading a titration volume V₁ ml of the PVSK titrant; step four. performing blank titration, and reading a titration volume V₂ ml of the PVSK titrant; and step 5. calculating a degree of deacetylation of chitosan fibers, D-D=[0.2032×C×f×(V₁-V₂)]/[m₂×(m₁/m)+0.0420×C×f×(V₁-V₂)]×100%. The method has a smaller error and is a high-sensitivity and simple method that can accurately measure a degree of deacetylation of chitosan fibers.