Method for measuring N-substitution degree, total substitution degree, and acetylation degree of hydroxypropyl chitosan

Abstract

The invention discloses a method for measuring an N-substitution degree, a total substitution degree, and an acetylation degree of hydroxypropyl chitosan. The method specifically comprises the following steps of: preparing a sample, wherein the preparing of the sample comprises the step a of drying the hydroxypropyl chitosan sample and the step b of adding deuterated reagent to the dried hydroxypropyl chitosan sample until it is completely dissolved; testing the sample, wherein testing the sample comprises acquiring a nuclear magnetic resonance spectrum of the hydroxypropyl chitosan by a nuclear magnetic resonance apparatus; and processing data; wherein processing the data comprises the following steps of: firstly carrying out the assignment of a wave spectrum from the acquired nuclear magnetic resonance spectrum, and then carrying out the area integral and the calculation of each proton peak; and acquiring the calculation formula of the N-substitution degree, the total substitution degree, and the acetylation degree of the hydroxypropyl chitosan. According to the method, an H9-N proton peak and an H9-O proton peak which are independent can be detected, and the proportion of sugarunits in which the hydroxypropylation of an amino group occurs in the hydroxypropyl chitosan molecule can be determined through the H9-N proton peak. Compared with the method of measuring the substitution degree in the prior art, the method is more specific and painstaking in the assignment, more accurate in the measurement, and efficient, simple and rapid in the multi-index.

Description

Technical field [0001] The invention belongs to the field of research and application of hydroxypropyl chitosan, and relates to a method for determining the degree of substitution of hydroxypropyl chitosan, in particular to a hydrogen nuclear magnetic resonance spectroscopy method for determining the degree of N-substitution of hydroxypropyl chitosan , Total substitution degree and acetylation degree method. Background technique [0002] Chitosan has good biocompatibility, biodegradability, stability, and safety, but its water solubility is poor and it can only be dissolved in acidic media, and chitosan is hydroxypropylated to produce hydroxypropyl shell Polysaccharides (HPCTS) can improve its solubility, thereby greatly broadening its application fields and development process. Studies have shown that hydroxypropyl chitosan has solubility, hygroscopicity, moisturizing, film-forming, foaming, free radical scavenging, antibacterial, and adsorptive properties. It is used in the fi...

AI Technical Summary

Problems solved by technology

The difference from ordinary small molecules is that there are a variety of intramolecular and intermolecular interactions in the structure of hydroxypropyl chitosan. Therefore, it is easy to quantitatively calculate the number of protons in the corresponding environment by using the integration of proton peaks at different chemical shifts. Introduce errors; on the other hand, because the test conditions are not optimized enough, the characteristic peaks overlap and cannot be measured as a single peak, resulting in the H in the denominator 2-8 Integral measurements are small, thereby significantly increasing the degree of substitution measurement, and more importantly, the presence of N-substitution cannot be detected

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