Page 16 - Analytical Electrochemistry 2d Ed - Jospeh Wang

Analytical Electrochemistry, Second Edition. Joseph Wang
Copyright # 2000 Wiley-VCH
ISBNs: 0-471-28272-3 (Hardback); 0-471-22823-0 (Electronic)

CHAPTER 1

FUNDAMENTAL CONCEPTS

1-1 WHY ELECTROANALYSIS?

Electroanalytical techniques are concerned with the interplay between electricity and
chemistry, namely the measurements of electrical quantities, such as current,
potential, or charge, and their relationship to chemical parameters. Such use of
electrical measurements for analytical purposes has found a vast range of applica-
tions, including environmental monitoring, industrial quality control, and biomedical
analysis. Advances in the 1980s and 1990sÐincluding the development of ultra-
microelectrodes, the design of tailored interfaces and molecular monolayers, the
coupling of biological components and electrochemical transducers, the synthesis of
ionophores and receptors containing cavities of molecular size, the development of
ultratrace voltammetric techniques or of high-resolution scanning probe microsco-
pies, and the microfabrication of molecular devices or ef®cient ¯ow detectorsÐhave
led to a substantial increase in the popularity of electroanalysis, and to its expansion
into new phases and environments. Indeed, electrochemical probes are receiving a
major share of the attention in the development of chemical sensors.
In contrast to many chemical measurements that involve homogeneous bulk
solutions, electrochemical processes take place at the electrode±solution interface.
The distinction between various electroanalytical techniques re¯ects the type of
electrical signal used for the quantitation. The two principal types of electroanaly-
tical measurements are potentiometric and potentiostatic. Both types require at least
two electrodes (conductors) and a contacting sample (electrolyte) solution, which
constitute the electrochemical cell. The electrode surface is thus a junction between
an ionic conductor and an electronic conductor. One of the two electrodes responds

1