pH and Ion Selective Electrodes

pH electrodes

The vast majority of pH electrodes comprise a thin glass bulb as the measuring electrode. They also require a reference electrode which may be incorporated into the measuring electrode (which is then known as a combination electrode). Both combination electrodes and electrodes with a separate reference are suitable for use with the:

We also supply a:

  • ET042 pH Electrode combination 'double junction' design resists fouling and is easily cleaned - especially good for biological samples. Supplied with guarded tip for general purpose use, and micro tip for use with small samples (about 0.5 mL or more). Good quality laboratory electrode.
  • ET060 Redox Electrode combination redox electrode (oxidation/reduction potential, ORP, electrode), featuring an easy to clean double junction and a platinum wire sensor.
  • ET5733 pH 'Tuff Tip' electrode. Specially hardened glass bulb for use in student laboratories.
  • ET044 Flow Thru pH electrode. Small internal volume; suitable for biological fluids.

Manufacturers of other pH electrodes include:

Ion Selective electrodes

Although there are several methods of construction most of these electrodes work by changing their potential (voltage) in response to changes in ionic concentration, Many pH meter are suitable and they are often marketed as 'pH/ISE meters'. Often these electrodes require a separate reference electrode (usually a silver/silver chloride reference is suitable). 

eDAQ makes suitable amplifiers for these electrodes:

Ion selective electrodes are available for many ionic species including sodium, potassium, calcium, chloride, nitrate, sulfide, etc, and are available from:

Combination and half cell electrodes

'Combination' pH electrodes and ISEs have an internal reference and can be directly connected to the BNC socket on the back of an eDAQ pH & ISE isoPod.

'Half cell' pH electrodes and ISEs must be used with a separate reference electrode. In this case the reference electrode is connected to the shell of the BNC socket on the back of an eDAQ pH & ISE isoPod, while the sensor electrode is connected to the center pin of the socket. You may find the following adaptors useful in connecting such electrodes to the isoPod:

 pHFET and ISFET electrodes

Occasionally you may come across pHFET (pH field effect transistor) and ISFET (ion selective field effect transistor) electrodes. In general these electrodes require a specially designed meter (they will NOT work with the pH/ISE isoPods, or most other standard pH meters). Usually the pHFET or ISFET electrode and meter will be obtained from the same manufacturer - you will need to check the meter specification to see is an analog signal is provided that is compatible with e-corder.

  • Sentron, TitanX meter and electrodes

Fibre Optic probes

It is possible to monitor pH by the use of fibre optic technology. The tip of the fibre optic probe is coated in a special dye which changes colour in a known way with changes in pH. A special meter must be used with the probe and both are usually bought from the same manufacturer.


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This page was last modified on: 12 Sep 2017 17:51:39