Peter Kissinger, William R. Heineman Laboratory Techniques in Electroanalytical Chemistry, Second Edition, Revised and Expanded

Peter Kissinger, William R. Heineman Laboratory Techniques in Electroanalytical...

(Parte 1 de 5)

Laboratory

Techniques in

Electroanalytical

Chemistry Second Edition, Revised and Expanded edited by

Peter T. Kissinger

Purdue University and Bioanalytical Systems, Inc. West Lafa yette, Indiana

William R. Heineman University of Cincinnati Cincinnati, Ohio

Library of Congress Cataloging-in-Publication Data

Laboratory techniques in electroanalytical chemistry / edited by Peter

T. Kissinger, William R. Heineman. - 2nd ed., rev. and expanded. p. cm.

Includes bibliographical references and index. ISBN 0-8247-9445- 1 (hardcover : alk. paper)

1. Electrochemical analysis-Laboratory manuals. I. Kissinger,

Peter T. 1. Heineman, William R. QD115.L23 1996

54 3 ' . 0 8 7-dc20

The publisher offers discounts on this book when ordered in bulk For more information, write to Special Sales/Professional Marketing address below.

This book is printed on acid-free paper.

Copyright 0 1996 by MARCEL DEKKER, INC. All Rights Reserved.

Neither this book nor any part may be reproduced or transmitted or by any means, electronic or mechanical, including photocopying, filming, and recording, or by any information storage and retrieval without permission in writing from the publisher.

MARCEL DEKKER, INC. 270 Madison Avenue, New York, New York 10016

Cment printing (last digit): 10 9 8 7 6 5 4 3 2

Preface

The text that had the most influence on the education of American chemists between the late 1950s and the late 1960s was Delahay’s mental Methods in Electrochemistry (1954). For well over a decade, played a dominant role in placing finite current electroanalytical its modern course-beyond the titrations, coulometry, polarography electrogravimetry of an earlier age. The membrane-covered oxygen developed by Clark in 1955 rapidly became one of the most important cal tools. Modern engineering mathematics began to conquer mass problems in the 1950s, and toward the end of that decade, operational ers revolutionized experimental electrochemistry.

In the 1960s, modern organic, inorganic, and biological electroanalytical chemistry advanced rapidly behind the advent of cyclic voltammetry, chronoamperometry, rotating ring disk electrodes, and the use of resonance and optical measurements coupled to electrochemical

After a burst of tremendous activity, it became clear during this chronopotentiometry was not competitive with controlled-potential In the second half of the 1960s, thin-layer electrochemistry had its electrodes other than mercury began to attract serious attention. It ered that platinum was surprisingly well behaved for studies in solvents, and even the likes of glassy carbon and carbon paste, to of thin films of metals and semiconductors deposited on glass, could solve chemical problems. Ralph Adams’ book, Electrochemistry at trodes (1969), surprised more than a few who did not believe it was

Anodic stripping voltammetry became a commercial reality and even to compete, for some elements, with atomic spectroscopy . Polarography ally diminished in importance for practical analysis through the early little company in Princeton, New Jersey, brought it out of hibernation ing differential pulse polarography commercially available via the cant op-amp-based electrochemical instruments.

cant clientele of users whose primary interest was not electrochemistry Two important fundamental new directions in the 1970s were toward modified electrodes and photoelectrochemistry . In addition, high-vacuum face spectroscopies began to play a serious role in electrochemical investigations. A significant new development of practical analytical importance of electrochemical flow cells for liquid chromatography, a development introduced thousands of pharmacologists, clinical chemists, and toxicologists electrochemistry for the first time. A small company in West Lafayette, ana, made this methodology easily accessible to non-electrochemists.

In the 1980s, it became widely recognized that there are advantages doing electrochemistry at very small electrodes. In the 1990s, benefits speed and access to electrochemistry in unusual media make microelectrodes quite routine. It is interesting that the microelectrodes of today are thousand times smaller than the “microelectrodes” of the ’~OS, ’~OS, What will the microelectrodes of tomorrow look like?

This book was conceived in 1970 by Peter Kissinger to provide of enabling a neophyte in electroanalytical chemistry to get started

During preparation of the first edition, the emphasis was expanded a pedagogical component. In the 12 years since the first edition, we’ve a number of suggestions based on actual classroom experience. Many have been incorporated in this second edition.

These days, research papers are necessarily brief with respect mental insights. Review chapters are often replete with unexplained erally confusing jargon and mathematics. Textbooks on instrumental have their good practical moments, but such moments are usually short, plete, and often out of date. None of these sources really does justice limited selection of material for the “bench chemist” wanting to moving in a hurry. The emphasis of this book is entirely on analytical, mechanistic neous), kinetic (homogeneous), and synthetic (laboratory-scale) Physical electrochemistry is not a direct concern, and equilibrium

(potentiometry) are intentionally omitted. There is no attempt to include chemical examples except where they are particularly illustrative and gogical value. No extensive review of the original literature is included, references to key reviews and papers of historical interest are

Authors have selected experimental approaches that work best and mented freely on outmoded or underdeveloped methods. The authors tors have made value judgments that undoubtedly will disappoint some

to applications. Chapters 2-5 are devoted to what the editors perceive commonly used techniques in electroanalytical chemistry today. These have passed the development stage and can now be considered approach in these chapters is designed to give the readers an intuitive standing of each technique without mathematical rigor. This is considering the excitation signal for each technique and the resulting tration-distance profiles that determine the consequent response signal. judgments are given to permit an educated selection of techniques given situation. Chapter 2 provides the fundamental concepts that are throughout the book. It is the editors’ opinion that Chapters 2-5 are use in graduate-level introductory courses in electroanalytical chemistry. Instrumentation for selected aspects of electroanalytical chemistry ered in Chapters 6-8. Although computers have made a tremendous electroanalytical instrumentation, many aspects of these chapters The basic configurations of a potentiostat have not changed since the although the electronic components themselves are dramatically different! to build your own potentiostat in Chapter 6, then see how to fine-tune

Chapter 7.

Chapters 9- 19 deal with some practical aspects of electroanalytical istry. These chapters are aimed at giving the novice some insight and bolts of electrochemical cells and solutions. In this second edition, emphasis has been given to obtaining and maintaining clean solutions, chapters have been added on chemically modified electrodes and electrochemi- cal studies at reduced temperature.

In the early 1970s, many electrochemists learned about digital from Steve Feldberg’s papers and Joseph Maloy ’s “underground” chapter, is now revised as Chapter 20. This field is 30 years old, and only commercial software extended its reach to a wider audience. Chapters 21-23 are for the neophyte trying to determine which can be useful for unraveling a mechanism and/or preparing a strategy thesis. The virtues of the key techniques described in Chapter 3 are here with specific chemical examples.

Chapters 24-29 are a potpourri of electroanalytical techniques cations. Hybrid techniques in which electroanalytical chemistry is combined luminescence, spectroscopy , or chromatography are discussed.

It is risky to predict the future, but the 1990s continue the 1970s: more chemistry; more practical organic, inorganic, and problem-solving; and more detailed knowledge of the chemical nature

between chemistry and electricity. We hope that this book is of some use to you in the course of your for which we wish you good luck-it certainly helps.

Many people have assisted with this project. We would like thank Peggy Sue Precup for her expertise in organizing numerous ing us overcome our English language deficiencies, and coordinating publisher. Rod Yoder and David Michell turned many rough comprehensible art. Drs. Adrian Bott and Jon Howell helped refine ters and their suggestions were invaluable.

Peter T. Kissinger William R.

Contents

Preface Contributors

1 An Overview

Peter T. Kissinger I. Some Philosophy

1. Progress and Prognosis 1.

Fundamental Concepts of Analytical Electrochemistry

Peter T. Kissinger, Car1 R. Preddy, Ronald E. Shoup, and William R. Heineman I. Introduction

1. Mass Transport: Linear Diffusion 1. The Charged Interphase IV.

V. VI. Liquid-Solid Adsorption

VII. Conclusion References

So Much Nomenclature, So Much Jargon Bibliography

The Nernst Equation and Electrochemical Reversibility Coupled Chemical Reactions and Chemical Reversibility

3 Large-Amplitude Controlled-Potential Techniques

William R. Heineman and Peter T. Kissinger

I. Introduction 1. 1. IV.

Potential-Step Techniques in Stationary Solution

Potential-Scan Techniques in Stationary Solution Controlled-Potential Techniques in Flowing Solution

References

1. Controlled-Current Techniques in Flowing Solution References

5 Small-Amplitude Controlled-Potential Techniques

Peter T. Kissinger and Thorns H. Ridgway

I. Introduction 1. Faradaic Impedance 1. Sinusoidal Alternating-Current Voltammetry IV. Cyclic Alternating-Current Voltammetry

V. Tensammetry VI. Step-Based Methods

VII. Staircase Voltammetry VIII. Differential Pulse Methods

IX. Square-Wave Methods X. Differential “Normal Pulse” Voltammetry

XI. Conclusion References

Peter T. Kissinger 6 Introduction to Analog Instrumentation

I. Classical Controlled-Potential Instrumentation 1. Controlled-Potential Instrumentation Based on Operational

Amp1 i fiers 1. Classical Controlled-Current Instrumentation

IV . Controlled-Current Instrumentation Based on Operational

Amplifiers

V. Microprocessor-Based Electrochemical Instrumentation VI. Conclusion

7 Overcoming Solution Resistance with Stability and Grace in Potentiostatic Circuits David K. Roe

Reference

I. Introduction 1. Input-Output Relations of Cells and Potentiostats

1. Stability of Potentiostat-Cell Circuits and the Role of R, IV. Compensation for iR, by Positive Feedback V. Achieving Stability Through Gain-Frequency Shaping

VI. Real Systems

Appendix Bibliography

1. 11.

DC Contact Measurement of Conductance Capacitive Contact Measurement of Conductance References

9 Electrochemical Cells

Fred M. Hawkridge

I. Design Concepts 1. Stationary-Solution Experiments 1. Convected-Solution Experiments IV. Thin-Layer Cell Design

V. Cells for Spectroelectrochemistry References

10 Carbon Electrodes

I. Introduction

1. Performance Criteria 1. Carbon Electrode Materials Properties

IV. Common Carbon Electrode Materials

V. Selection of Carbon Electrodes for Analytical Applications References

Richard L. McCreery and Kristin K. Cline

1 Film Electrodes

James L. Anderson and Nicholas Winograd I. Introduction

1. Applications of Thin-Film Electrodes

1. Properties of Film Electrodes IV. Metal Film Electrodes V. Carbon Film Electrodes

VI. Semiconductor Film Electrodes

Techniques of Cell Design Based on Film Electrodes Prospects for Disposable, Integrated Sensor Systems References

12 Microelectrodes

Adrian C. Michael and R. Mark Wightman

I. Introduction 1. Construction of Microelectrodes

1. Diffusion at Microelectrodes IV. High-speed Cyclic Voltammetry V. Ohmic Drop at Microelectrodes

13 Chemically Modified Electrodes

Charles R. Martin and Colby A. Foss, Jr.

I. Introduction 1. 1. IV.

Methods for Preparing Chemically Modified Electrodes Electrochemistry at Chemically Modified Electrodes Characterization and Analysis of Chemically Modified Electrodes Applications of Chemically Modified Electrodes

References VI, Conclusions

14 Mercury Electrodes Zbign iew Galus

I. Introduction

1. Dropping Mercury Electrode 1. Hanging Mercury Drop Electrode

IV. Static Mercury Drop Electrode V. Streaming Mercury Electrodes

VI. Mercury Film and Other Types of Mercury Electrodes References

15 Solvents and Supporting Electrolytes

Albert J. Fry

I. Introduction 1. Recommended Solvents and Electrolytes

1. Some Other Solvents

IV . V . Experimental Procedures

Solvent- and Electrolyte-Dependent Phenomena

Appendix: Other Literature References

16 Electrochemical Studies at Reduced Temperature

Dennis H. Evans and Susan A. Lerke I. Introduction

Motivations for Variation of the Temperature in

Electrochemical Studies Examples of the Study of the Rates of Coupled Chemical Reactions Practical Aspects of Electrochemical Studies at Low Temperatures References

1. Molten Salt Systems 1. Apparatus and Techniques References

18 Vacuum-Line Techniques

Vladimir Katovic, Michael A. May, and Csaba P. Keszthelyi

I. Introduction 1. Vacuum Line

1. Electrochemical Glassware for the Vacuum Line References

19 Electrochemistry in the Dry Box

Steven N. Frank and Su-Moon Park

I. Introduction 1, Choosing an Inert-Atmosphere System

1. Experimental Procedures

Appendix References

20 Digital Simulation of Electrochemical Problems J. T. Maloy

I. 1. 1.

XI11 . XIV .

xv .

Introduction The Finite Difference Representation of Fick’s Laws The Model Diffusion Coefficient: Defining At and Ax

Establishing Initial and Boundary Conditions

Dimensionless Parameters A Sample BASIC Program Chronocoulometry Other Nernstian Electrode Boundary Conditions Homogeneous Kinetics Parametric Substitutions Electrogenerated Chemiluminescence Chronopotentiometry

Linear Sweep and Cyclic Voltammetry Simulation of Rotating Disk Hydrodynamics Simulation of Rotating Ring Disk Behavior The Steady-State Assumption Beyond the Basics References

1. Reduction of p-Chlorobenzonitrile 1. Oxidation of Adrenaline IV. Oxidation of a-Tocopherol V. Concluding Remarks References

2 Electroorganic Synthesis

Eberhard Steckhan

I. What Is Electroorganic Synthesis?

1. 1. Technically Interesting Processes IV. Classification of Electroorganic ReactionH

V. Experimental Factors and Techniques

Advantages and Disadvantages of Electroorganic Reactions

References

23 Instructional Examples of Electrode Mechanisms of Transition

Metal Complexes William E. Geiger

I. Electrode Mechanisms 1. Obtaining High-Quality Data 1. Mechanistic Studies

IV. Examples of Selected Mechanisms

V. Comments on Second-Order Homogeneous Reactions References

24 Elect roc hemical Preconcent rat ion

Joseph Wang

I. Why Preconcentration?

1. Stripping Analysis 1. Electrochemical Preconcentration for Spectroscopic Analysis

References

25 Controlled-Current Coulometry

David J. Curran

I. Introduction

1. Coulometric Generation of Reagents 1. Coulometric Titrations

References

1. Coulometric Methods 1. Voltammetric Methods References

(Parte 1 de 5)

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