Ion-Selective Electrode Methodology Volume I Editor Arthur K. Covington Reader in Physical Chemistry University of Newcastle Newcastle upon Tyne England Boca Raton London New York CRC Press is an imprint of the Taylor & FranCcisR GCrou Pp,r aens isn,fo Irmnca .business Boca Raton, Florida First published 1979 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 Reissued 2018 by CRC Press © 1979 by CRC Press, Inc. CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. 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Disclaimer The publisher has made every effort to trace copyright holders and welcomes correspondence from those they have been unable to contact. ISBN 13: 978-1-315-89478-2 (hbk) ISBN 13: 978-1-351-07388-2 (ebk) Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com PREFACE The idea for a volume of ion-selective electrodes, hailed as an important advance in analytical chemistry, in CRC's UNISCIENCE Series arose out of the great interest shown in my article for CRC's Critical Reviews in Analytical Chemistry published in 1974 (Crit. Rev. Anal. Chem., 1973, 3 (4), 355-406). In inviting experts to join me in the project, I was very much concerned to have those who were actively engaged in working with ion-selective electrodes and who could write on practical matters from firsthand experience. Their enthusiasm is apparent from the result which grew to two volumes. The intention was to produce a book which perforce would never be far from the laboratory, although CRC's use of Handbook in another connection precludes our use of that word in the title. I have, intentionally, wielded a strong editorial hand bringing, I hope, terminology and symbols to a common basis. I thank the contributors for their forebearance and their ready compliance with my suggestions. We trust you, the reader, will find these two volumes valuable in this second decade of ion-selective electrode potentiometry. A.K.C. Newcastle upon Tyne, England January 1979 THE EDITOR Arthur Kenneth Covington, B.Sc., Ph.D. , D.Sc. (Reading) C.Chem. FRIC, is Reader in Physical Chemistry in the University of Newcastle upon Tyne, U.K. and is well known for his work on glass, ion-selective and reference electrode systems, as well as for his studies of electrolyte solutions by thermodynamic and spectroscopic meth- ods. Dr. Covington represents The Chemical Society (London) on the British Stand- ards Institution Committees on the pH Scale, pH meters and Glass Electrodes, is Prin- cipal U.K. Expert on, and Leader of, the International Standards Organization Working Group on "pH and Potentiometry", and Titular Member of IUPAC Com- mission V5 on Electroanalytical Chemistry. He co-edited Physical Chemistry of Or- ganic Solvent Systems, Plenum, London, 1973 and Hydrogen-Bonded Solvent Sys- tems, Taylor and Francis, London, 1968. CONTRIBUTORS D. M. Band, Ph.D. E. Pungor, Ph.D., C. Sc. Senior Lecturer Professor, Head, Sherington School of Physiology Institute for General and Analytical St. Thomas Hospital Medical School Chemistry London, England Technical University Budapest, Hungary Richard P. Buck, Ph.D. Professor of Chemistry Malcom Riley, Ph.D. University of North Carolina Chief Chemist Chapel Hill, North Carolina Electronic Instruments, Ltd. Chertsey, Surrey, England Peter Burton Formerly Electronics Engineer Electronic Instruments, Ltd. R. J. Simpson Chertsey, Surrey, England Senior Research Officer SIRA Institute Arthur K. Covington, D. Sc. Chislehurst, Kent, England Reader in Physical Chemistry University of Newcastle J. D. R. Thomas, D. Sc. Newcastle upon Tyne, England University Reader in Chemistry University of Wales Instutute of Robert W. Cattrall, Ph.D. Science and Technology Senior Lecturer in Inorganic and Cardiff, Wales Analytical Chemistry La Trobe University KlaraToth, Ph.D., C. Sc. Bundoora, Victoria, Australia Associate Professor Institute for General and Analytical Phillip Davison, Ph.D. Chemistry Assistant Analytical Superintendent Technical University BP Chemicals, Ltd. Budapest, Hungary Salt End, Hull, England T. Treasure, M.S., F.R.C.S. G. J. Moody, Ph.D. Senior Registrar in Senior Lecturer in Chemistry Cardiac Thoracic Surgery University of Wales Institute of Brompton Hospital Science and Technology London, England Cardiff, Wales Pankaj Vadgama, M.B., B.S., B.Sc., Geza Nagy, Ph.D., C. Sc. M.R.C. Path. Senior Research Fellow Medical Research Council Training Institute for General and Analytical Fellow Chemistry Department of Clinical Biochemistry Technical University Royal Victoria Infirmary Budapest, Hungary Newcastle upon Tyne, England TABLE OF CONTENTS Volume I Chapter 1 Introduction: Basic Electrode Types, Classification, and Selectivity Considerations . . 1 A. K. Covington Chapter 2 Instrumentation for Ion-Selective Electrodes 21 P. R. Burton Chapter 3 Practical Techniques for Ion-Selective Electrodes 43 R. J. Simpson Chapter 4 pX Standards 67 A. K. Covington Chapter 5 Glass Electrodes 77 A. K. Covington Chapter 6 Liquid Ion Exchange Types 85 A. K. Covington and P. Davison Chapter 7 Poly vinyl Chloride Matrix Membrane Ion-Selective Electrodes Ill G. J. Moody and J. D. R. Thomas Chapter 8 Heterogeneous Membrane, Carbon Support, and Coated Wire Ion-Selective Elec- trodes 131 Robert W. Cattrall Chapter 9 Crystalline and Pressed Powder Solid Membrane Electrodes 175 Richard P. Buck Index 251 Volume II Chapter 1 Gas-Sensing Probes 1 M. Riley Chapter 2 Enzyme Electrodes 23 P. Vadgama Chapter 3 Ion-Selective Electrodes in Medicine and Medical Research 41 D. M. Band and T. Treasure Chapter 4 Analytical Methods Involving Ion-Selective Electrodes (Including Flow Methods). . .65 E. Pungor, G. Nagy, and K. Toth Index 123 Chapter 1 INTRODUCTION: BASIC ELECTRODE TYPES, CLASSIFICATION, AND SELECTIVITY CONSIDERATIONS A. K. Covington TABLE OF CONTENTS I. Introduction and Scope 1 II. Historical Development 3 III. Classification of Materials 8 A. Glass 9 B. Insoluble Inorganic Salts 9 C. Organic Ion Exchangers and Chelating Agents 10 IV. Electrode Forms and Construction 12 V. Theoretical Considerations 13 A. Derivation of the Nernst Relations 13 B. Selectivity and Interferences 15 References 19 I. INTRODUCTION AND SCOPE The term "ion-selective electrodes" is applied to a range of membrane electrodes which respond selectively towards one (or several) ion species in the presence of others. The formerly used but less preferred term "ion-specific" is not favored1 because these electrodes are rarely specific in their response to one ionic species over others, although this is a desirable property sought by the designer of new electrodes. The description "membrane" is used here in its broadest sense to denote a thin section of electrically conducting material separating two solutions across which a potential develops. Often, the term "membrane" has associated with it the notion of permeability to a species present in the flanking solutions. However, although this is undoubtedly true with certain porous biological and synthetic membranes, the actual mechanism of electrical conduction in general varies with the type of membrane material; indeed, it may change within it. The hydrogen ion-responsive glass electrode, well known for its use in pH measure- ments, falls within the definition given above. A number of reviews" and two books4 5 have dealt with its properties, use, suggested mechanism of functioning, and related studies of glass itself, so it is not the author's intention to devote space to a discussion of these. Glass electrodes responsive to alkali metal cations are a more recent devel- opment, and are discussed in Chapter 5, Volume I. All types of glass electrode are, however, considered as ion-selective electrodes. Unlike some developments in science, no startling new principle heralded the arrival