Ion Selective Electrodes ISE

Why Use Ion Selective Electrodes?

The main reasons Ion selective electrodes are popular:-
  The initial set up is inexpensive (typically one only needs a pH/mV meter or Ion meter, the electrodes, a stirring stand, and some basic chemicals)
  The measurements are unaffected by colour or turbidity in the sample
   The sample pre-treatment is usually simple
   The measurements can be done in “real time”, and can be easily automated
   Wide dynamic range-usually several decades

Where Are They Used?

Ion selective electrodes or ISE’s are commonly used in environmental, food and agriculture, power plants, research and in clinical applications.
Examples include:  Fluoride in drinking water, Calcium in beer, Nitrates in plants, Chloride in canned food products,  and Calcium in dental studies.

Limitations

- selectivity/interferences
- accuracy, typically 2-5% relative
- calibrating solutions and samples need to have the ionic strength adjusted
- lifetime and maintenance requirements of polymer membrane electrodes
- sample pre treatment is sometimes necessary for non-ideal samples

Care and Maintenance

Care must be taken to avoid damaging the membrane surface. Follow the instructions supplied with the electrodes to assure maximum life. After extensive use, the membranes may become coated with contaminants or become scratched. The solid state types such as Chloride and Fluoride can usually be easily repaired with fine emery and then washing with distilled water to remove debris. You should never touch the membranes of ISE's such as Calcium and Potassium, because it is very easy to damage the surface. These should instead be rinsed in standard solution and the deposits removed with a fine jet of water.