Record the alginate NMR and select one very good distinguished peak from alginate nmr (Integral value say one) and compare with the same peak integral values of alginate methacrylate (Again same peak integral value keep one) after methacrylation. The diference is the degree of methacrylation.

It is quite difficult task espesially with a spectrum of polymer of such poor quality to be compaired with spectra of narrow lines of usual monomers. In order to be sure that you received alginate will you receive 13C NMR spectra to destinguish clearly carboxyl carbons of alginate - ester from original metacrilyc acid or ester. By 1H NMR spectra of that quality it is difficult to see where is a product and where is a simple mixture of reagents