Fig. 3.

¹H NMR spectra of precipitated fractions (Fig. 1, step XVI) using sodium citrate (I), sodium oxalate (II), sodium carbonate (III), sodium hydroxide (IV), and commercial alginic acid (V). The integrated peak areas a, b, and c were calculated between 5.02–4.88 ppm, 4.63–4.49 ppm, and 4.45–4.27 ppm, with a baseline between the start and the end point of integration as the lower constraint for the integration areas