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. 2019 Feb 11;24(3):634. doi: 10.3390/molecules24030634

Figure 2.

Figure 2

Figure 2

(a) Absorption spectrum of onion skin aqueous extract before (black) and after (red) the first dyeing cycle (100-fold diluted with H2O). Insert: absorption spectrum of quercetin in water. (b) Absorption spectra of untreated wool (UW, blue) and dyed wool in onion skin aqueous extract (T1, black) and its residue (T2).