Electroanalysis: Theory and Applications in Aqueous and Non-Aqueous Media and in Automated Chemical Control (Technqs & Instrumentation in Analytical)

401 Pages·1986·19.4 MB·English

by  E. A. M. F. Dahmen

TECHNIQUES AND INSTRUMENTATION IN ANALYTICAL CHEMISTRY - VOLUME 7
ELECTROANALYSIS
THEORY AND APPLICATIONS IN AQUEOUS AND
NON-AQUEOUS MEDIA AND IN AUTOMATED
CHEMICAL CONTROL
TECHNIQUES AND INSTRUMENTATION IN ANALYTICAL CHEMISTRY
Volume 1 Evaluation and Optimization of Laboratory Methods and Analytical
Procedures. A Survey of Statistical and Mathematical Techniques
by D.L. Massart, A. Dijkstra and L. Kaufman
Volume 2 Handbook of Laboratory Distillation
by E. Krell
Volume 3 Pyrolysis Mass Spectrometry of Recent and Fossil Biomateriats.
Compendium and Atlas
by H.L.C. Meuzelaar, J. Haverkamp and F.D. Hileman
Volume 4 Evaluation of Analytical Methods in Biological Systems
Part A. Analysis of Biogenic Amines
edited by G.B. Baker and R.T. Coutts
Part 6. Hazardous Metals in Human Toxicology
edited by A. Vercruysse
Volume 5 Atomic Absorption Spectrometry
edited by J.E. Cantle
Volume 6 Analysis of Neuropeptides by Liquid Chromatography and Mass
Spectrometry
by D.M. Desiderio
Volume 7 Electroanalysis. Theory and Applications in Aqueous and Non-Aqueous
Media and in Automated Chemical Control
by E.A.M.F. Dahmen
TECHNIQUES AND INSTRUMENTATION IN ANALYTICAL CHEMISTRY - VOLUME 7
ELECTROANALYSIS
THEORY AND APPLICATIONS IN
AQUEOUS AND NON-AQUEOUS
MEDIA AND IN AUTOMATED
CHEMICAL CONTROL
E.A.M. F. Dahmen
Emeritus Professor, Twente University of Technology, Enschede, The Netherlands
E LSEVl ER
Amsterdam - Oxford - New York - Tokyo 1986
ELSEVIER SCIENCE PUBLISHERS B.V.
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Distributors for the United States and Canada:
ELSEVIER SCIENCE PUBLISHING COMPANY INC.
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L.ibrsrv of Cnngreea Cataloging-inPubl~~tioDna ta
Dahmen, E. A. Y. F. (Edouard Albert Msrie Fernad),
1914-
Electroanalysis : theory and applications in aqueous
and non-aqdeous media and in automated chemical control.
(Techniques and instrumentation in analytlcnl chemis-
try ; v. 7)
Includes bibliographies and indexes.
1. Electrochemical analysis. I. Title. 11. Series.
QD115.D25 1986 543' .0871 86-8992
ISBN 0-444-42534-9 (U.S. )
ISBN 0-444-42534-9 (Val. 7)
ISBN 0-444-41744-3 (Series)
3 Elsevier Science Publishers B.V.. 1986
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V
CONTENTS
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IX
List of symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . XI
General introduction . . . . . . . . . . . . . . . . . . . . . . . . XV
A . ELECTROANALYSIS (SYSTEMATIC TREATMENT)
Chapter 1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1. Definitions and selected bibliography . . . . . . . . . . . . . . .
1.2. Systematics and standard abbreviations . . . . . . . . . . . . .
1.2.1. Systematics . . . . . . . . . . . . . . . . . . . . . . . .
1.2.2. Standard abbreviations . . . . . . . . . . . . . . . . . .
1.3. Electrochemical cells . . . . . . . . . . . . . . . . . . . . . .
1.3.1. Electrodes . . . . . . . . . . . . . . . . . . . . . . . . .
1.3.2. Cell features . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 2
Non-faradaic methods of electrochemical analysis . . . . . . . . . . . 11
2.1. Conductometric analysis . . . . . . . . . . . . . . . . . . . . . 11
2.1.1. Conductometry . . . . . . . . . . . . . . . . . . . . . . 11
2.1.1.1. Electrolytic conductance . . . . . . . . . . . . . . 11
2.1.1.2. Practice of conductometry . . . . . . . . . . . . . 17
2.1.2. Conductometric titration . . . . . . . . . . . . . . . . . . 21
2.1.3. High-frequency titration . . . . . . . . . . . . . . . . . . 25
2.2. Potentiometric analysis . . . . . . . . . . . . . . . . . . . . . 25
2.2.1. Potentiometry . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.1.1. Indicator electrodes, reference electrodes and diffusion
potentials . . . . . . . . . . . . . . . . . . . . . 25
2.2.1.2. Normal electrodes . . . . . . . . . . . . . . . . . 28
2.2.1.2.1. Redox electrodes . . . . . . . . . . . . . 28
2.2.1.2.2. Electrodes of the lst, 2nd and 3rd kinds . . 44
2.2.1.3. Membrane electrodes . . . . . . . . . . . . . . . . 47
2.2.1.3.1. General theory of membrane electrodes . . . 48
2.2.1.3.2. Types of membrane electrodes . . . . . . . 56
2.2.1.3.2.1. Solid-state membrane electrodes 56
2.2.1.3.2.2. Liquid membrane electrodes . . . 64
2.2.2. Practice of potentiometry . . . . . . . . . . . . . . . . . 69
2.2.3. ISFETs in potentiometry . . . . . . . . . . . . . . . . . . 80
VI
2.2.4. Potentiometric titration . . . . . . . . . . . . . . . . . . 82
2.2.4.1. Acid-base titrations . . . . . . . . . . . . . . . . 82
2.2.4.2. Precipitation titrations . . . . . . . . . . . . . . . 87
2.2.4.3. Complex-formation titrations . . . . . . . . . . . . 88
2.2.4.4. Redox titrations . . . . . . . . . . . . . . . . . . 89
2.2.4.5. Experimental titration curves and end-point detection 91
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Chapter 3
Faradaic methods of electrochemical analysis . . . . . . . . . . . . . 97
3.1. Pragmatic treatment of the theory of electrolysis . . . . . . . . . 97
3.2. Kinetic treatment of the theory of electrolysis . . . . . . . . . . 102
3.2.1. Current-potential curves at fixed redox concentrations . . . 104
3.2.2. Current-potential curves at non-fixed redox concentrations 106
3.2.3. The concept of overpotential . . . . . . . . . . . . . . . . 109
3.3. Voltammetry . . . . . . . . . . . . . . . . . . . . . . . . . . 111
3.3.1. Voltammetry at a non-stationary electrode, in particular at the
dme (polarography) . . . . . . . . . . . . . . . . . . . . 111
3.3.1.1. Conventional (DC) polarography . . . . . . . . . . 111
. .
3.3.1.1.1. Principles of conventional polarography 112
3.3.1.1.2. Theory of conventional polarography . . . . 114
3.3.1.1.3. Practice of conventional polarography . . . 127
3.3.1.2. Newer methods of polarography . . . . . . . . . . . 133
3.3.1.2.1. Advanced DC polarography . . . . . . . . 133
1. Rapid DC polarography . . . . . . . . . 133
2 . Current-sampled DC polarography (Tast
polarography) . . . . . . . . . . . . . 135
3. Subtractive DC polarography . . . . . . 137
4 . Derivative DC polarography . . . . . . . 138
5. Linear sweep voltammetry at the dme . . 139
6. Pulse polarography . . . . . . . . . . . 143
3.3.1.2.2. AC polarography . . . . . . . . . . . . . 148
.
1 Polarography with superimposed AC
signal . . . . . . . . . . . . . . . . . 148
2. Oscillographic AC polarography . . . . . 158
3.3.1.3. Polarographic titration . . . . . . . . . . . . . . . 161
3.3.2. Voltammetry at stationary and hydrodynamic electrodes . . 161
3.3.2.1. Voltammetry at stationary electrodes . . . . . . . . 161
1. Linear sweep voltammetry (chronoamperometry) . 162
2 . Pulse voltammetry . . . . . . . . . . . . . . . . 163
3. Voltammetry with superimposed AC signal . . . . 165
4 . Chronopotentiometry . . . . . . . . . . . . . . 165
5. Stripping voltammetry . . . . . . . . . . . . . . 174
VII
3.3.2.2. Voltammetry at hydrodynamic electrodes . . . . . . 186
3.3.2.2.1. Voltammetry at rotating electrodes . . . . . 186
3.3.2.2.2. Voltammetry at other hydrodynamic elec-
trodes . . . . . . . . . . . . . . . . . . . 191
3.3.2.3. Voltammetric titration . . . . . . . . . . . . . . . 193
3.3.2.3.1. Constant-current potentiometric titration . . 195
3.3.2.3.2. Differential electrolytic potentiometric
titration . . . . . . . . . . . . . . . . . 196
3.3.2.3.3. Amperometric titration . . . . . . . . . . 197
3.3.2.3.4. Dead-stop end-point titration . . . . . . . . 200
3.3.2.3.5. Potentiometric dead-stop end-point titration 206
3.3.2.3.6. Polarovoltry . . . . . . . . . . . . . . . 206
3.3.3. Practice of voltammetry in general . . . . . . . . . . . . . 206
3.4. Electrogravimetry . . . . . . . . . . . . . . . . . . . . . . . . 211
3.4.1. Constant-current electrolysis . . . . . . . . . . . . . . . . 212
3.4.2. Constant-potential electrolysis . . . . . . . . . . . . . . . 212
3.4.3. Controlled-potential electrolysis . . . . . . . . . . . . . . 212
3.4.4. Electrolysis at a mercury pool . . . . . . . . . . . . . . . 214
3.5. Coulometry . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
3.5.1. Controlled-potential coulometry . . . . . . . . . . . . . . 217
3.5.2. Coulometric titration (controlled-current coulometry) . . . . 218
3.5.3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . 224
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
B . ELECTROANALYSIS IN NON-AQUEOUS MEDIA
Chapter 4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
4.1. Theory of electrochemistry in non-aqueous media . . . . . . . . . 231
4.1.1. Acid-base systems in non-aqueous media . . . . . . . . . . 232
4.1.1.1. Differentiation between acids . . . . . . . . . . . . 244
4.1.1.2. Differentiation between bases . . . . . . . . . . . . 247
4.1.2. Choice of solvents for acid-base reactions . . . . . . . . . 251
4.1.3. Associates (donors-acceptor complexes or salts,
self-aggregates and hydrogen-bonded conjugates) . . . . . . 254
4.1.3.1. Donor-acceptor complexes or salts . . . . . . . . . 254
4.1.3.2. Self-aggregates . . . . . . . . . . . . . . . . . . . 255
4.1.3.3. Hydrogen-bonded conjugates . . . . . . . . . . . . 255
4.1.4. Exploratory acid-base titrations in solvents with a very low
dielectric constant (E) . . . . . . . . . . . . . . . . . . . 257
4.1.4.1. Acid-base titrations in protogenic solvents with low E 257
4.1.4.2. Acid-base titrations in protophilic solvents with low E 264
4.1.4.3. Acid-base titrations in inert solvents with low E . . . 268
4.1.4.4. Comparison of acid-base equilibria in solvents with
low E and in water . . . . . . . . . . . . . . . . . 273
VIIT
4.1.5. Kedox systems in non-aqueous media . . . . . . . . . . . . 2 75
4.2. Practice of electroanalysis in non-aqueous media . . . . . . . . . 279
4.2.1. Non-faradaic methods of electroanalysis in non-aqueous media 283
4.2.2. Faradaic methods of electroanalysis in non-aqueous media . . 289
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
C . ELECTROANALYSIS IN AUTOMATED CHEMICAL CONTROL
Chapter 5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
5.1. Nature of chemical control . . . . . . . . . . . . . . . . . . . 3 03
5.2. Character and degree of automation in chemical control . . . . . 305
5.3. Role of electroanalysis in automated chemical control . . . . . . . 3 11
5.4. Automated electroanalysis in laboratory control . . . . . . . . . 312
5.4.1. Automated autonomic electroanalytical systems in laboratory
control . . . . . . . . . . . . . . . . . . . . . . . . . . 312
5.4.2. Systems with electroanalytical detection in laboratory control 322
5.4.2.1. Automated titrations with electroanalytical detection 322
5.4.2.1.1. Automated discontinuous titration . . . . . 322
5.4.2.1.2. Automated continuous titration . . . . . . 329
5.4.2.2. Flow techniques with electroanalytical detection . . 335
5.4.2.2.1. Non-separational flow techniques . . . . . 335
5.4.2.2.2. Separational flow techniques . . . . . . . . 344
5.4.3. Electroanalysis and computerization . . . . . . . . . . . . 3 54
5.5. Automated electroanalysis in plant control . . . . . . . . . . . . 3 55
5.5.1. Special sampling requirements in plant control . . . . . . . 355
5.5.2. Special measurement requirements in plant control . . . . . 356
5.6. Automated electroanalysis in environment control . . . . . . . . 358
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
Appendix
Table of selected half-wave potentials for inorganic substances . . . . 365
Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369
Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
IX
PREFACE
The tremendous success of the International Congress on Polarography, held
at Prague from August 25th to 29th 1980 in honour of Prof. Jaroslav Heyrovskjr,
illustrates once more the great importance of Electroanalysis, not only from a
theoretical point of view but also as a source of experimental techniques of
increasing applicational potential.
Since the appearance of the well known books by Kolthoff, Lingane and
Delahay in the early 1950s, thousands of papers on electroanalysis appeared;
however, at present there are few up-to-date comprehensive textbooks on
Electroanalysis. It is the aim of this book to fill that gap to a certain extent, by
presenting on the one hand a systematic treatment of electroanalysis and its
commonly used techniques on a more explanatory basis, and on the other by
illustrating the practical applications of these techniques in chemical control
in industry and of health and environment. As such control today requires the
increasing introduction of automation and computerization, electroanalysis
with its direct input and/or output of electrical signals often has advantages
over other techniques, especially because recent progress in electronics and
computerization have greatly stimulated new developments in the electro-
analysis techniques themselves.
I have tried to make the book self-contained, apart from the assumption that
the reader has an adequate knowledge of basic physical chemistry and will
consult the selected bibliography when necessary. Moreover, having kept
practice constantly in mind, I hope I have succeeded in building a welcome
bridge between electroanalytical chemistry as a science and electrochemical
analysis as an art.
I am most indebted to Prof. Dr. F. Verbeek of the State University of Ghent,
Belgium, for his kindness in criticizing many topics in the manuscript, and to
that University in general for providing library facilities.
Also, I would like to pay tribute to my former co-workers, especially those in
the field of titration in non-aqueous media: Dr. H. B. van der Heijde, Dr. N.
van Meurs and Dr. M. Bos, of whom the last mentioned also deserves my
additional appreciation not only for his work on electroanalysis in solvents of
relatively low dielectric constants, but also for his development of automated
and computerized methods of electroanalysis. Some other investigators, such
as Dr. H. Donche (State University of Ghent, Belgium) and Dr. B. H. van der
Schoot (Twente University of Technology, The Netherlands), most obligingly
provided me with details of their recent work even before it had been published.
My sincere thanks are also due to Mr. A. A. Deetman for his literature
research on automation of electroanalysis and to his employers AKZO Zout
Chemie, Hengelo, The Netherlands, for their kind permission to carry out this
task. Further, I am indebted to many firms and their representatives in The