H+-selective glass electrode (pH electrode)

Introduction

H+-selective glass electrodes (pH electrodes) can be manufactured from the classic Corning 015 glass which consists of silicon dioxide, sodium oxide & calcium oxide in the molar ratio of 72.2:21.4:6.4. A newer glass that is more selective to H+ consists of silicon dioxide, lithium oxide & calcium oxide in the molar ratio of 68:25:7, but many other compositions are suitable. With the older glass, interference from Na+ occurs at pH > 8.0, which increases with increasing temperature. The glass membrane of the electrode may be shaped to fit the requirements of the application.

More general terms

• glass electrode (ion-specific electrode, ISE)