Electroanalytical strategies with

Electroanalytical Strategies with Chemicalfy Modified Interfaces... 

Electroanalytical chemistry is one of the areas where advantage of the unique properties of SAMs is clear, and where excellent advanced analytical strategies can be utilized, especially when coupled with more complex SAM architectures. There are a number of examples where redox reactions are used to detect biomaterials (357,358), and where guest—host chemistry has been used to exploit specific interactions (356,359). Ion-selective electrodes are an apphcation where SAMs may provide new technologies. Selectivity to divalent cations such as Cu " but not to trivalent ions such as Fe " has been demonstrated (360). 

The basic strategy in the application of electroanalytical methods in studies of the kinetics and mechanisms of reactions of radicals and radical ions is the comparison of experimental results with predictions based on a mechanistic hypothesis. Thus, equations such as 6.28 and 6.29 have to be combined with the expressions describing the transport. Again, we restrict ourselves to considering transport governed only by linear semi-infinite diffusion, in which case the combination of Equations 6.28 and 6.29 with Fick s second law, Equation 6.18, leads to Equations 6.31 and 6.32 (note that we have now replaced the notation for concentration introduced in Equation 6.18 earlier by the more usual square brackets). Also, it is assumed here that the diffusion coefficients of A and A - are the same, i.e. DA = DA.- = D. 

Perhaps the area of analysis in which electrochemistry has had the biggest impact on society is in biosensors, notably the glucose biosensor [48], Although Volume 9 is concerned with bioelectrochemistry, it is important that this area of electroanalytical chemistry is represented appropriately in Volume 3. Consequently, Schuhmann and Bonsen provide an overview of the physical principles and appKcations of biosensors in Chapter 2.11. A comprehensive overview is given of amperometric, potentiometric, conducti-metric and impedimetric formats for biosensors, and the relative merits of each are fully assessed. Potential new directions are highlighted, particularly connected to miniaturization and multisensor array detection strategies. 

Electroanalytical innovation and development of novel sensor electrodes are often driven by progress in materials chemistry. In particular for boron-based structures and assemblies the detection of saccharides plays a very prominent role. Monomeric as well as polymeric borate and boronic esters are reactive towards diols and lead to novel electroanalytical tools as well as new signal amplification strategies. There are many new opportunities arising and this overview will cover some of the recent developments in solid state, surface, and molecular boron structures with application in electroanalysis. 

In this chapter, the difhculties associated with applying conventional electroanalytical techniques, such as steady-state microelectrode voltammetry, RDE voltammetry, and dc cyclic voltanunetry with numerical simulation for the purpose of quantifying diffusivity in RTILs, are highlighted. In developing a strategy for overcoming these issues, we first outline the fundamentals of convolution voltammetry and then discuss a range of situations where electroanalytical applications of these techniques in RTILs have been employed successfully. 

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