Electroanalytical Chemistry

Principles, Best Practices, and Case Studies

Gary A. Mabbott

• Editorial: Wiley
• Año: 2020
• ISBN:
  9781119538585
• Edición: 1
• Categoría: Physical Sciences
• Categoría: Physical & Theoretical Chemistry

Provides a strong foundation in electrochemical principles and best practices

Written for undergraduate majors in chemistry and chemical engineering, this book teaches the basic principles of electroanalytical chemistry and illustrates best practices through the use of case studies of organic reactions and catalysis using voltammetric methods and of the measurement of clinical and environmental analytes by potentiometric techniques. It provides insight beyond the field of analysis as students address problems arising in many areas of science and technology. The book also emphasizes electrochemical phenomena and conceptual models to help readers understand the influence of experimental conditions and the interpretation of results for common potentiometric and voltammetric methods.

Electroanalytical Chemistry: Principles, Best Practices, and Case Studies begins by introducing some basic concepts in electrical phenomena. It then moves on to a chapter that examines the potentiometry of oxidation-reduction processes, followed by another on the potentiometry of ion selective electrodes. Other sections look at: applications of ion selective electrodes; controlled potential methods; case studies in controlled potential methods; and instrumentation. The book also features several appendixes covering: Ionic Strength, Activity and Activity Coefficients; The Nicolsky-Eisenman Equation; The Henderson Equation for Liquid Junction Potentials; Selected Standard Electrode Potentials; and The Nernst Equation Derivation.

• Introduces the principles of modern electrochemical sensors and instrumental chemical analysis using potentiometric and voltammetric methods
• Develops conceptual models underlying electrochemical phenomena and useful equations
• Illustrates best practice with short case studies of organic reaction mechanisms using voltammetry and quantitative analysis with ion selective electrodes
• Offers instructors the opportunity to select focus areas and tailor the book to their course by providing a collection of shorter texts, each dedicated to a single field
• Intended as one of a series of modules for teaching undergraduate courses in instrumental chemical analysis

Electroanalytical Chemistry: Principles, Best Practices, and Case Studies is an ideal textbook for undergraduate majors in chemistry and chemical engineering taking instrumental analysis courses. It would also benefit professional chemists who need an introduction to potentiometry or voltammetry.

1
Basic Electrical Principles

Electrochemical methods of analysis measure electrical quantities in order to yield chemical information. In some cases, the measurement is an electric current (the movement of charge). In other cases, the measurement is a voltage (the amount of energy available to move a charge). Both of these techniques are useful for quantitative analysis of a chemical species, but they can also be used to determine characteristic properties that are useful for qualitative analysis. Some types of qualitative information can be useful for evaluating new materials, such as catalysts.

In describing the fundamentals of electroanalytical methods, this book emphasizes conceptual models. An effort has been made to tie conceptual models of phenomena to basic mathematical relationships in order to provide a foundation to use in reasoning through new situations. Greater insight into electroanalytical phenomena is the intended result. As with other branches of science, new developments displace older techniques. A fundamental understanding of the phenomena upon which electroanalytical tools operate enables one to appreciate the basis for new techniques and related progress in the field. A conceptual understanding also provides a good starting point for learning about other areas of science and technology that involve electrochemical processes. Electrochemical principles play important roles in many natural phenomena and in modern technology [1]. Among these fields are the subjects of energy storage and conversion; biological processes such as cellular action potentials, tissue repair, and growth [2]; electrochemical synthesis; separation technology, nanoparticles, and materials processing in the electronics industry.

Electroanalytical techniques are among the oldest instrumental methods of chemical analysis. They are still widely used for important analyses and are likely to continue to be important for many more decades. Although electroanalytical chemistry is a mature field in many ways, new developments in the realm of selective sensors and the application of electrochemical methods to demanding tasks, such as in vivo monitoring of neurotransmitters and remote environmental analysis continue to make instrumental analysis based on electrochemistry relevant. Some attributes of electrochemical analysis that lead to special advantages are summarized in Table 1.1.

TABLE 1.1 Attributes of electroanalytical techniques

Attribute	Makes possible
Sensitive	Low detection limits
Small	In vivo monitoring
	Measurement in tiny volumes
Simple construction	Implantable devices
Inexpensive	Mass production
	Use in poor communities
Simple operation	On‐site operation
	Health care monitoring
	Remote sensing

Improved detection limits and greater selectivity have led to a greater range of applications. Some methods are capable of quantifying specific analytes down to the picomolar level. Another appealing attribute of electrochemical sensors is that they are relatively easy to miniaturize making them adaptable to a variety of new situations such as in vivo monitoring [3]. The sensing element can be very small making it possible to measure quantities of chemical species in tiny volumes or in precise locations, such as at the terminus of a single neuron. Electrochemical methods usually require only very simple accessories. That makes them portable and, in some cases, it makes medical implantation of the sensor possible. Sensors can often be made of inexpensive materials that can be mass produced making them attractive for personal healthcare monitors, such as the handheld glucose monitor used by millions of people to manage their diabetes [4]. Other electroanalytical instruments are capable of a wide range of experiments making them well‐suited to studying organic reaction mechanisms associated with electron transfer.

Before launching into the principles of electrochemistry, it is appropriate to say a word about the structure of this book. Chapter summaries appear at the beginning of each chapter in the form of an overview. Unlike reading a novel, here it is helpful for you to know the plot in advance. It helps you to know what to take away from the story. It is worthwhile to read the overview both before and after reading the other sections of the chapter. This book is aimed at students of instrumental analysis, but it is also intended to be a solid introduction to electroanalytical principles for any professional scientist. A lot of care has gone into explaining physical mechanisms and underlying concepts. Recent developments leading to new and interesting methods with better performance characteristics and a wide range of applications are described in most chapters. However, there is much more material than can be reasonably absorbed during a typical two‐to‐three‐week unit of a college instrumental analysis course. Therefore, in addition to summarizing the major ideas, these chapter briefings tell you what sections to read, if time is short.

1.1 Overview

This first chapter is a bit different. It serves as an introduction to basic electrical phenomena and should be read in its entirety. Among the important ideas discussed in this chapter are a few definitions. The term “voltage” refers to the electrical potential energy of a charged particle. It is a measure of the force of attraction or repulsion on a single charged particle by the local density of charges in the neighborhood. The density of charges in the earth itself is thought to be reasonably constant and, as such, provides a local reference point for electrical energy. Instruments are often attached to a conductor in contact with the earth. This reference point is often referred to as “ground,” and it is considered to be a point representing 0 V.

One volt equals on...