Chemically modified substrate derivatization

It is important at this stage to define first-order and second-order derivatization. First-order CMEs are prepared by adding the chemically active group directly to an electrode substrate. There is a limited number of instances where this approach is appropriate. Second-order derivatization, which involves adding the chemically active group to a previously modified substrate, greatly expands the number of different CMEs which can be prepared ... 

In order to enhance or modify the chemical selectivity of an SERS substrate, it is possible to chemically derivatize the metal surface. For example, covalent bonding of a hydrocarbon to a silver island film should selectively adsorb nonpolar analytes from an aqueous solution. The general approach is shown schematically in Figure 13.24 for the case of metal ions detected by a surface-bound complexing agent (47). Field enhancement is provided by the substrate, while adsorption selectivity results from the chemistry of the derivatized... 

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