Hi,
I dissolved quaternized chitosan (with GTMAC) in D2O and 1%DCl and did H-NMR to calculate the degree of substitution. However, I see a large peak at 4.7ppm (D2O?) and some overlapped peaks after 4.7ppm which I can't really tell which one to use for degree of substitution calculations. I would appreciate any feedbacks and article suggestions.
Also, I'm new to NMR sample preparation. I wonder if dissolving quaternized chitosan in 1%DCl/D2O in a sealed glass bottle is enough. Thanks!
Hi Yechan,
I think your question will be answered with the following link:
Conference Paper 1H-NMR Analysis of Degree of Substitution in N,O-Carboxymeth...
Regards
Markus
Hi Yechan
C13 NMR and FT-IR are better techniques for characterisation of your product. You have to be careful when running NMR in highly acidic solvents as some probes don't handle it very well. Perhaps D2O on its own will do the job as your product is a salt. I found a useful paper if you would like to have a look (
Macromolecules 2016, 49, 3, 1049-1059). Please note this is not my paper.
Good luck
Sannia
The peak at 4.8 is related to the solvent D2O not used in determination process , while the peak at 3.3 is related to the free methyl groups of the Quaternary moiety which you will use it to determinate the degree of Quaternization , also from elemental analysis you can determine the degree of substitution using this equation:
Nitrogen contents (N %) of QCs were measured with an
elemental analyzer (CHN-O-Rapid, Foss Hera us GmbH, Hanau,
Germany). The DS value of QC was determined by nitrogen content
and calculated according to the following eq 1:
(DS)=162 ×N %⁄ (14-151.5 ×N %)
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