Identification of Species Via Solid-State Transformations

The electrochemical processes involving Prussian blue and organic dyes studied above can be taken as examples of solid state redox processes involving transformation of a one solid compound into another one. This kind of electrochemical reactions are able to be used for discerning between closely related organic dyes. As previously described, the electrochemistry of solids that are in contact with aqueous electrolytes involves proton exchange between the solid and the electrolyte, so that the electrochemical reaction must in principle be confined to a narrow layer in the external surface of the solid particles. Eventually, however, partial oxidative or reductive dissolution processes can produce other species in solution able to react with the dye. 

The characterization of individual dyes is complicated by (a) the existence of a significant structural similarity, and consequently, reactivity, for different dyes (b) several dyes are composed of mixtures of pigmenting compounds, in turn having 

These electrochemical processes can be accompanied by secondary reactions in solution. The presence of additional phenol groups can complicate the electrochemical response of flavonoids, giving rise to additional electrochemical processes [150-158]. This fact is of interest for analytical purposes, because 

Examples of the application of solid state electrochemistry to identifying dyes in textile samples can be provided. Thus, Fig. 2.17 compares the square wave voltam-mograms of (a) saffron blank, and (b) sample from a Tibet temple, attached to fluorine-doped tin oxide (FTO) electrodes immersed into acetate buffer. After initiating the potential scan at -0.85 V in the positive direction, two separated oxidation 

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