Does the operating life of an ISE depend on the number of samples analysed?
ISE operation is based on ion-exchange / charge-transfer principles. Thus there is hardly any consumption of materials or wear and tear on components when samples are analysed. Assuming that the electrode is not exposed to damaging chemicals, the only deterioration is due to the gradual corrosion (oxidation, hydration, leaching) of the membrane, the plastic body, and the adhesive used to attach the membrane to the body (or to physical damage to the membrane surface or to the pin connecting to the electrode head). The extent of the corrosion is affected by the length of time the electrode is immersed or exposed to the atmosphere rather than the number of samples analysed. Experience has shown that electrodes can be immersed continuously for months without deteriorating. This demonstrates that, for individual sample measurements with average immersion times of two or three minutes, many thousands of samples can be measured with one electrode.
