Reference electrodes, aqueous solutions miniaturized

The auxiliary and reference electrodes in electronic and other spectroelectrochemical experiments are similar to those used in conventional electrochemical cells. They must be small enough to fit into the cell without complicating its construction. Common auxiliary electrodes are small platinum wires, paddles, or coils. Reference electrodes (see Chapter 4) are frequently Ag/Ag+ or AgCl because these can be miniaturized. In non-quantitative appUcations, silver wire coated with AgCl or a simple silver wire as a pseudo reference (quasi-reference electrode, QRE) can be used. However, commercially available aqueous and non-aqueous Ag/Ag+ in which the electrode is separated from the analyte solution via a frit are preferable because they are more stable. The majority of electronic spectroelectrochemical experiments are conducted using OTEs in either thin layer (finite) or semi-infinite diffusion regimes. 

A new type of flow cell has been developed for detection of heavy metal ions in aqueous solutions, based on the flow injection method The cell contains two chemically modified field effect transistors (CHEMFETs) of which one is selective for the supporting electrolyte ion (in this case a 0 1 M potassium ion solution) and the other is selective for the heavy metal ion to be detected (Cd ", Pb " ) The differential signal of the reference electrode CHEMFET and the heavy metal ion CHEMFET in the flow cell system which has been presently developed will be evaluated for miniaturization and further integration in a micro total analysis system... 

This research is often motivated by the miniaturization of electronics and the potential molecules may have in devices, even at the level of a single molecule. The electron tunneling through redox single porphyrin molecules in aqueous solution has been investigated. In this system, the substrate and tip Fermi levels can be flexibly adjusted relative to the molecular orbitals by controlling the substrate potential versus a reference electrode in the solution, at a constant sample-tip bias. By tuning the substrate Fermi level to an un-... 

Figure 4.2.8 shows cyclic voltammograms in the presence (solid line) and absence (dotted line) of 1 mmol dm ferrocenedimethanol in an aqueous KCl solution. Voltammograms in Fig. 4.2.8a were recorded with the miniature [Cgmim nCiCiN l-coated AgCl reference electrode, and those in Fig. 4.2.8b are obtained with a conventional AgjAgCl electrode. 

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