An Environmentally Friendly Compact Microfluidic Hydrodynamic Sequential Injection System Using Curcuma putii Maknoi & Jenjitt. Extract as a Natural Reagent for Colorimetric Determination of Total Iron in Water Samples

Figure 3

The proposed complexation mechanism of quercetin 3-O-glucuronide and iron. (a) Possible chelating sites of iron (iron (III) or iron (II)) ions on quercetin 3-O-glucuronide. (b) Oxidation of the flavonoid 3ʹ,4ʹ-dihydroxyl (catechol group) site to a semiquinone-type radical and possibly to a quinone [25].

(a)

(b)