Electroanalytical devices

The term artificial tongue is used in two main branches of science. The first one concerns the neurophysiological studies aimed at developing perceptual supplementation devices, with biomedical engineering applications to human disabilities. The second utilization of the term artificial tongue concerns, instead, the laboratory analytical instruments used in combination with chemometric techniques to obtain complex information (often sensory-like, but not only) on samples. As for this latter meaning, also the synonymous electronic tongue is frequently used, particularly for electroanalytical devices. 

Copper has been measured in soil using a portable electroanalytical device based on stripping voltammetry. In marine chemistry, sediments have been sampled and analysed in real-time by in situ solid-state voltammetric micro-electrodes. The analyser was used to examine levels of various redox species and trace metals, e.g. iron and manganese, in salt marsh sediments and other matrices. 

Although the course of a reaction can be monitored by chemical or even visual means, most kinetic methods rely on instruments for this purpose, optical (photometric and fluorimetric) and electroanalytical devices being by far the most common choices. In this context, it is worth emphasizing the ability of stopped-flow mixing methodology to boost the performance of the chemiluminescence reaction to which it is specially suited on account of the fast transient nature of chemiluminescence reactions. 

Furthermore, the development of electroanalytical devices and relevant measurement procedures often presents quite complex issues in terms of reliability, repeatability, and reproducibility of the responses obtained. This is a problem that, in the case of modified electrodes, presents particularly complex aspects. Similar systems often exhibit a behavior that is far from being accounted for by simple or known physical laws that would offer a previous reference to the decision about a good or bad way to work. Hence, a critical analytical exam of the results obtained is mandatory, being ready to adopt even non-trivial treatment of the data. 

This well-defined and experimentally confirmed relationship is one reason why RDEs are preferred as electroanalytical devices and for determining kinetic constants (see Section 3.2.2.2). It is important to remember, however, that Eq. (2.27) and (2.28) assume an electrode rotating in an infinite amount of electrolyte, which is not true of a real RDE cell. It is better to obtain an actual value for for the system being modeled (Example 3.2.3.1), or if this... 

Zaouak, O., Authier, L., Cugnet, C., Normandin, E., Champier, D., Rivaletto, M., Potin-Gautier, M., 2010. Electroanalytical device for cadmium speciation in waters. Part 2 automated system development and cadmium semicontinuous monitoring. Electroanalysis 22, 1159-1165. 

The utilization of graphite powder and graphite electrodes in combination with MN4 macrocyclic metal complexes has been explored in several types of electro-analytical devices with applications in quite distinct fields. The selected examples discussed on this topic wiU be related to MN4-MC adsorbed onto graphite electrodes or combined with graphite powder and a binder for preparing modified carbon pastes electrodes, which is a very simple approach to incorporate MN4-MC into an electroanalytical device. 

Fig. 3 a Picture of the low-cost paper-based electroanalytical device fabricated using CoPc-modified carbon paste microelectrode b Cyclic voltammograms obtained using the modified caibon paste electrode (CPE + CoPc) and unmodified (CPE) in the presence and absence of L-cysteine c Analytical curve obtained by chronoampeiometric measurements by applying 0.6 V on the WE (working electrode). Reprinted with permission from [34]. Copyright (2013) American Chemical Society... 

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