Chitosan (CTS) is a natural basic polysaccharide, which have no a very effective way to determine its content now. In this paper, we used cellulase combined with mixed acid under ultrasound assisted (CAU) method to hydrolyze CTS into glucosamine, which can react with diaminobenzene formaldehyde acid alcohol solution to form red compound under alkaline condition acetyl acetone. The red compound has the UV absorption at 525nm measured by spectrophotometry, which can further calculate the content of CTS. The results showed that the optimal conditions were that the sample amount was 3mg, enzyme-substrate ratio was 80mg/g and pH 5.2 as well as water bath at 50 °C for 30min and then supersonic at 50°C for 7hr in the enzymolysis step, 0.168mol/L hydrochloric acid was 0.8ml, 75% sulfuric acid was 3.5ml, the boiling water bath for 30min and ultraphonic at 50°C for 60 min in the acid hydrolysis step. The average recovery was 100.02 ± 5.51%, and the content of CTS was 96.58 ± 1.54%. The results indicated that the mentioned methods are easy and effective for the quantitative analysis of CTS.
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