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. 2019 Nov 27;5(11):e02913. doi: 10.1016/j.heliyon.2019.e02913

Figure 4.

Figure 4

UV-VIS spectra of thin PVA cryogels: (1) activated by 1% GA and stained with 50 μM DNPH; (2) average spectrum of three non-activated gels; (3) non-activated gel, reduced by NaBH4; (4) difference spectrum: (1)–(2); (5) 50 μM DNPH; (6) 50 μM DNPH +1.25 mM GA. Solvent: 90% ethanol, containing 40 mM H2SO4.