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Ion-Selective, pH, ORP, DO Electrodes ISE/pH Ion Analysers 4 & 8 Channel Analysers Aqualyser Range 'Multisens' Measuring Systems
Award of Excellence: June 2006
A Beginners Guide to Ion-Selective Electrode Measurements
"has been selected as one of the best educational resources
on the Web"
by studysphere.com

A Beginners Guide to Ion-Selective Electrode
Measurements

Chris C Rundle BSc, PhD. (Nico2000 Ltd, London, UK.)
Biography of author

First Public Version: 05 May 2000,     Last Update: 5 May 2014.
Major revision, including introduction of internet links, diagrams and illustrations: June 2004
Please Email
nico2000ltd@btinternet.com with any comments or suggestions for improvement.

Printer-friendly PDF version ( 30 x A4 pages. Mainly text - only a few illustrations. )

CONTENTS

1)    FOREWORD, RATIONALE AND ACKNOWLEDGEMENTS

2)    INTRODUCTION TO ION SELECTIVE ELECTRODES
         a) Applications.
         b) Advantages

3)    BASIC THEORY OF ISE MEASUREMENTS.
         a) The pH Electrode.
         b) Differences Between pH and Other Ion-Selective Electrodes.

4)    TYPES OF ION SELECTIVE ELECTRODES
         a) General Discussion.
         b) Crystal-Membrane Electrodes: e.g. Fluoride.
         c) Impregnated-PVC-Membrane Electrodes: e.g. Potassium.
         d) Care and Maintenance of ISEs.

5)    REFERENCE ELECTRODES
         a) The Silver / Silver Chloride Single Junction Reference Electrode.
         b) Double Junction Reference Electrodes.
         c) Liquid Junction Potentials.
         d) Combination Electrodes.
         e) Multiple Electrode Heads: Separable Combinations.

6)    LIMITATIONS and CONSTRAINTS
         a) Ionic Interference and Selectivity Coefficients.
         b) Ionic Strength and Activity Coefficients: Activity versus Concentration.
         c) Ionic Strength Adjustment Buffers.
         d) Potential Drift.

7)    CALIBRATION THEORY
         a) Linear Range.
         b) Total Measuring Range.
         c) Limit of Detection.

8)    CALIBRATION PRACTICE
         a) Standard Solutions.
         b) Minimising Drift Effects During Calibration.
         c) Frequency of Calibration.

9)    MEASURING PROCEDURES
         a) Adding ISAB.
         b) Taking Readings and Minimising Drift Effects.
         c) Cleaning Electrodes and Minimising Hysteresis Between Samples.

10)    METHODS OF ANALYSIS
         a) Direct Potentiometry.
         b) Incremental Methods: Standard Addition, Sample Addition & Subtraction.
         c) Potentiometric Titrations.

11)    ACCURACY AND PRECISION OF SAMPLE MEASUREMENTS.
          a) General Discussion.
          b) Reproducibility Experiments Using an Ammonium Electrode.
          c) Reproducibility of Chloride Measurements.
          d) Standard Addition & Sample Addition Methods.
          e) Conclusions from Experimental Data.

12)    TYPES OF MEASURING DEVICES AND DATA PROCESSING
         a) Analogue Meters.
         b) Digital Meters.
         c) Self-Calibrating, Direct-Reading Ion Meters.

13)    RECENT DEVELOPMENTS
         a) Meterless Computer Interfaces.
         b) Data Processing Software.
         c) Multi-Component Analysis.

14)    RECENT RESEARCH INTO CORRECTIONS FOR INTERFERING IONS
         a) Rationale and Problems.
         b) Creating a Calibration Net.
         c) Interfering Ion Correction Software.

APPENDICES - Available at www.nico2000.net.

A)    GLOSSARY OF TERMS AND CALCULATIONS

B)   INTERNET LINKS & BIBLIOGRAPHY
        Including over 100 links to Research Papers and Articles about
        Ion-Selective Electrode theory and practice available on the WWW.

C)    OPERATING INSTRUCTIONS FOR ELIT ION-SELECTIVE ELECTRODES
        Includes all the latest updates

D)   CATALOGUE OF NICO2000 ELECTROCHEMICAL PRODUCTS (pdf) .
        7 x A4 pages with illustrations.

E)   MS "POWER POINT" PRESENTATION
        About ELIT Ion Analyser Systems.

F)    DEMONSTRATION SOFTWARE FOR ELIT ION ANALYSERS
        Download or request a free CD

ELIT Ion Analyser Systems
ELIT Ion Analyzers
Ammonium Barium Bromide Cadmium Calcium
Chloride Copper Cyanide Fluoride Iodide
Lead Mercury Nitrate Nitrite Perchlorate
Potassium Sodium Silver Sulphide Sulfide
Thiocyanate (Sulphate) (pH) (ORP) (DO)
  • ELIT Ion Analyzers measure ion concentrations, pH, Temperature, Redox (ORP) in aqueous solutions.
  • Multi-channel versions permit continuous, simultaneous monitoring of different sensors in one solution or in several different solutions at the same time.
  • Based on proven Ion Selective Electrode Technology.
  • Versions available for also monitoring Dissolved Oxygen (DO), Conductivity and Biosensors.
  • Connect sensor electrodes directly to a lap-top or desk-top PC - no need for conventional meter.
  • Software available for any generation of Windows-based PC.
  • Complete system includes: Ion Selective Electrode, Reference Electrode, Electrode Head, pH electrode, Temperature Sensor, Electrode-Computer Interface, Ion Analyser Software, Comprehensive Instructions.


  • APPLICATIONS:
  • Water Quality Analysis: surface and ground waters, fish ponds, aquaculture, sewage, industrial effluent.
  • Food and Drink Quality Control, Bio-reactors and Fermentors.
  • Pharmaceutical Research, Agricultural Research, Medical Research,…etc.

Go To Chapter 1




Biography for Dr Chris C Rundle, Nico2000 Ltd, London, UK


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Chris Rundle worked for more than 25 years for the Natural Environment Research Council (British Geological Survey) as an Analytical Chemist / Geochronologist / Isotope Geochemist / Mass Spectrometrist. In the last few years at BGS a significant part of his work was the development of software for the automatic control of analysis, data acquisition and processing. His first degree in Chemistry and Geology was at the University of London (External joint honours BSc, 1968) and his PhD thesis was "The Chronology of Igneous Intrusion in the English Lake District", awarded by Birkbeck College, London, 1982.

After taking early retirement from NERC in 1994, Dr Rundle joined Nico2000 Ltd in 1997 and started to work with Ion-Selective Electrodes. Since then he has helped develop measuring techniques and software for a unique range of electrode-computer interfaces (as an alternative to conventional pH/Ion meters) and written software manuals, analytical procedures and electrode operating instructions for ISE measurements. He also developed and maintains the company website at www.nico2000.net and answers customer enquiries and problems. To maintain a comprehensive and up-to-date resource for students and researchers, the website is frequently updated if these enquiries reveal new analytical requirements or problems or ambiguities/deficiencies in the online help and advice .





















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