Beginners Guide to ISE Measurement. Chapter 1.

FOREWORD AND RATIONALE.

Ion-Selective Electrodes (ISEs) have been widely used for more than thirty years, yet it is still remarkably difficult for the beginner to find an adequate explanation of the basic principles and applications of this technology. Manufacturer’s advertising pamphlets tend to oversimplify the principles of operation and gloss over the difficulties and limitations, whereas numerous scientific research papers and specialist text books tend to overwhelm the non-specialist with endless equations for complex electrochemical reactions, masses of mathematical formulae, and many unnecessary details. Moreover, most of these works are now more than twenty years old and do not contain any reference to modern computer-based techniques.

It is hoped that this guide will fill the gap between these two extremes. It’s aim is to give sufficient information, in relatively simple language and with the minimum of technical detail and mathematics, to enable the non-specialist to gain an appreciation of the advantages and disadvantages of ISE measurements and to assist the new analyst in achieving the best possible results when using this technology. It also gives details of the latest developments in data acquisition and processing using meterless computer interfaces and sophisticated software.

I would like to express my deep gratitude to Heinz Kreuzberg for introducing me to ISEs, for encouraging me to write this guide and, most importantly, for masterminding much of the development of the computer interfaces discussed in the last part of the work. I am also indebted to Dr. Alexander Kapustin for giving me basic training in the theory and practice of ISE measurements and for patiently answering my interminable questions, and to Dr. Jonathan Slater for providing additional background information by allowing me to see his course notes on Principles of Electroanalysis and Potentiometry.

The latter part of this guide would not have been possible without the inspired and dedicated work of Yiying Cui and Feng Xiao in developing and writing the computer programmes which were essential to permit any further advances in the techniques and data processing of ISE measurements. Their patience and understanding in the face of many months of bombardment with interminable requests for changing and re-writing the software cannot be praised too highly.

Much of the information provided here has also been confirmed by reference to the British Standards Specification for Ion-Selective Electrodes, BS7310:1990, and gleaned from several ISE manufacturer’s catalogues and advertising material.

Chris C Rundle. 5 May 2000.