Generalities of Electrochemical Methods

A second reason is that spectrochemical methods appear somewhat more amenable to automation or mechanization than electrochemical methods. An extreme example of this can be seen in the clinical analysis laboratory. In 1971, for instance, one particular hospital performed nearly a half-million chemical tests, 91% of which were done with spectrochemical methods and instruments [2]. This, of course, was due to its use of automated clinical analyzers, which are primarily optical in approach. 

There are, however, many times when electrochemical methods can provide essentially the same information as other methods, thus offering an alternative approach, and other times when only electrochemistry will provide the answer or will provide the best answer to the problem at hand. 

Although it is very difficult to consider electrochemical methods in general versus other methods in general, electrochemical methods do have certain advantages. First of all, electrochemical instrumentation is comparatively inexpensive. The most expensive piece of routine electrochemical instrumentation costs about 15,000, with most commercial instrumentation under about 3000. By contrast, some sophisticated nonelectrochemical equipment, such as nuclear-magnetic-resonance or mass spectrometers, may run over a quarter of a million dollars. 

Another advantage (or disadvantage, depending on the problem at hand) of many electrochemical methods is that they respond to the activity of a chemical species rather than to the concentration. An example where this may be of importance is the calcium level in serum. Ion-selective electrodes respond to free, aquated Ca ions, whereas the usual clinical method for serum calcium is flame photometry, which measures the total calcium present including a large amount tied up as protein-bound calcium. The more important physiological parameter, the measure of the effective level of calcium actually available for participation in various enzymatic 

It can be safely said that in recent years there has been a renaissance of interest in quantitative electrochemical methods. This has been brought about primarily by two factors the development of ion-selective potentiometric electrodes, which can quantitatively monitor most of the common ionic species in solution (Chap. 2) and the introduction of a new generation of inexpensive commercial voltammetric instrumentation based on pulse methods (Chap. 3), which has increased the sensitivity of electrochemical methods by several orders of magnitude. 

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