you can used HPLC methods

HPLC? Really? I have not noticed any publications regarding that. Can you point me any? Thanks

Dear Sir. Concerning your issue about the determination of esterification degree of pectin . The change in infrared spectrum of the pectin films of different origin accompanying the transformation of potassium pectinate into potassium pectate was investigated. It was revealed that the intensity ratio of the bands v a s (COO-) at 1608 cm"' and v(C = 0) este r at 1745 cm"1 corresponding to fully deesterified pectin and methyl pectate, respectively, is a constant independent of the kind of fruit used for the isolation of pectin as well as of the pectin composition. Thus, it has been proved that the method of the determination of the degree of esterification of the pectin by methanol based on the measurement of absorbances in the maxima of these bands can be used for different kinds of pectins. The degree of esterification of pectin (E %) can be determined with absolute error ± 1.3%. I think the following below links may help you in your analysis:

https://www.chempap.org/file_access.php?file=322a218.pdf

http://www.scielo.br/pdf/asagr/v33n3/v33n3a01.pdf

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2621.1986.tb11245.x

Thanks

Thank you very much for your kind answer.

you can used FTIR spectroscopy

see this work

Determination of the Degree of Methylation and Acetylation of Pectins by HPLC September 1986 · Food Hydrocolloids 1(1):65-70 DOI: · 10.1016/S0268-005X(86)80008-X

Nasser Belboukhari Thanks a lot!