How to calibrate an Ion Selective Electrode Meter

Proper calibration of ion selective electrode (ISE) meters is vital to ensure accurate results. Here are some top tips for calibration:

• Calibration standard concentrations should bracket your expected sample – you should use at least 2 standard calibration standards which bracket the expected concentration of your sample, and these concentrations should be decades apart e.g. 0.1mg/L and 1mg/L
• Calibrate with the lowest concentration first – this limits the effect of contaminants if the electrode is not cleaned properly with deionized water in between calibration standards
• Don’t introduce contaminants – the preparations of dilutions must be carried out with analytically clean glassware and should be prepared on the day of use
• Keep the temperature constant – the temperature alters the activity of the ions in the solution and therefore to maintain the highest accuracy, all your samples and calibration solutions should be the same temperature
• Stir your sample – this ensures the sample is well-mixed
• Use ionic strength adjustment buffers – this should be added in equal amounts to your calibration standards and your sample. ISABs will adjust the standards/sample so they have the same ionic strength.

The TRUEscience multi-parameter meter, based on an Android App, makes calibration easy and intuitive. It harnesses the accuracy of standard laboratory grade sensors with the computing power of an Android tablet, expanding measurement capabilities, connecting to the cloud and making your readings smart. Being able to access the features of the TRUEscience system on a familiar device such as a tablet or phone makes navigation of the app simple. Check out the below video to see an ISE calibration in action: