Are Ion Selective Electrodes (ISE) measurements temperature compensated or corrected?

Document ID

Document ID TE7337

Version

Version 3.0

Status

Status Published

Published Date

Published Date 09/20/2018
Question
Are Ion Selective Electrodes (ISE) measurements temperature compensated or corrected?
Summary
ISE measurement and temperature
Answer
Sample measurement by an ISEs is not corrected or compensated for temperature (with the exception of pH which is technically an ISE for H+). Because of this, variations in temperature will impact results. It is important that all standards and samples are at the same temperature during calibration and measurement within ± 2 °C.

This is one of the reasons that stirring is important for ISE measurement and calibration. It not only ensures that the Ionic Strength Adjuster is well mixed, but it also that the sample or standard in the beaker is all at temperature equilibrium, and that there aren't hot or cold spots in the beaker impacting the results depending on where the electrode is located.

The most common way to guarantee that everything is at the same temperature is to allow for standards and samples to all equilibrate to ambient temperature in a climate controlled lab. Which is another reason that ISE measurement is not recommended for field use, but instead recommended for benchtop measurement.

If the samples are at a consistent temperature and there is a concern that samples that are collected and measured after reaching equilibrium with ambient temperature will no longer be representative of the sample source, then standards can be adjusted to the sample temperature before calibration. Then samples can be measured immediately after being collected.

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