pH and ion-selective microelectrodes are rapidly finding an increasing number of applications in the study and control of living (and nonliving) systems. They are unique in their capacity to mea sure chemical species without altering natural or controlled envir onmental conditions. Furthermore, these potentiometric tools mea sure the activity of the chemical species in contrast to conven tional ones that measure total concentration. The "Workshop on Ion-Selective Microelectrodes" is designed to provide an insight into the principles, theory, fabrication, tech niques, present limitations, goals, and applications of some of these tools. The importance and types of microelectrodes and guidelines for their application in biological systems are discussed by Berman. Their present limitations are reviewed by Durst. He warns that their use in analyzing living matter should be approached with caution because of the ill-defined nature of biologic systems. Techniques are presented next for the fabrication of pH (Hebert), antimony (Green and Giebisch, and Malnic et al.), oxygen (Whalen), then single-barrelled (Wright, Walker and Ladle, Morris and Krnjevic) and double barrelled (Zeuthen et al., and Khuri) potassium and chloride liquid ion-exchanger microelectrodes. Difficulties with and fabrication of reference and glucose electrodes are covered, respectively, by Durst and Wright, and Bessman and Schultz.

Inhalt
I. Theory, Potential and Existing State of Development.- 1. Perspective: Ion-Selective Microelectrodes: Their Potential in the Study of Living Matter In Vivo.- 2. Ion-Selective Electrode Response in Biologic Fluids.- 3. Glass Microelectrodes for pH.- 4. Some Problems with an Intracellular PO2 Electrode.- 5. Some Problems with the Antimony Microelectrode.- II. Intracellular Applications.- 6. Ionic Activity in Identifiable Aplysia Neurons.- III. Kidney.- 7. Use of Potassium Ion-Exchanger Electrode for Microanalysis.- 8. Kinetic Analysis of Renal Tubular Acidification By Antimony Microelectrodes.- 9. Electrochemical Potentials of Potassium and Chloride in the Proximal Renal Tubules of Necturus maculosus.- IV. Brain.- 10. Some Measurements of Extracellular Potassium Activity in the Mammalian Central Nervous System.- 11. Microelectrode Registration of Ion Activity in Brain.- V. Myocardium.- 12. Intracellular Potassium and Chloride Activities in Frog Heart Muscle.- VI. Clinical Applications.- 13. Muscle pH, PO2, PCO2 Monitoring: A Review of Laboratory and Clinical Evaluations.- 14. Progress Toward a Glucose Sensor for the Artificial Pancreas.