Identification of Species by Electrochemical Methods

As previously noted, the identification of components in works of art and archaeological objects is a difficult task during their scientific examination. Samples usually appear as heterogeneous or (apparently) homogeneous solid materials, frequently incorporating different portions; for instance, preparative, pigmenting, and protective layers in paints. At first glance, conventional electrochemical methods are applicable for identifying pigmenting species in solutions resulting from the chemical attack of acids, bases, and organic solvents, etc., of the solid sample. This approach offers two main drawbacks: (i) the disposal of sample amounts restricted to the ng-μm range, thus requiring high sensitive methods, and especially (ii) the loss of analytical information due to the chemical attack on the sample. Thus, an acidic attack of a sample containing either red or yellow cadmium pigments yields Cd²⁺ ions in solution, which can be identified by conventional stripping voltammetry. However, this procedure does not inform on the composition of the original pigment.