EDT directION manufacture a full range of standards, filling solutions and Ionic Strength Adjustment Buffers (ISABs).

All ISE measurements require calibration using typically two standards plus the addition of an ISAB. Details of the type and concentration of standards and ISABs can be found in both the ISE instruction manual or the Application sheet where published.

Ionic Strength Adjustment Buffers (ISAB) are required for accurate Ion analysis using Ion Selective Electrodes (ISEs). The EDT Potassium ISAB has been specially formulated to allow the buffering of all samples and standards to the same Ionic Strength without interfering with the Potassium measurement. The Potassium ISAB comes in 500ml leak-proof bottles with an inner seal. Typical addition is 2ml of ISAB to every 100ml of standard and sample.

The ionic strength of standards and samples are not the same thereby the ability of ions to freely move around varies from sample to sample. This means that the effective activity of ions will vary between these solutions. ISEs measure activity as they can only sense ions that come into contact with the sensor surface. To ensure all ions have an equal probability of contacting the ISE the total Ionic Strength of all solutions should be equal (or as close as possible). This is achieved by adding a small volume of ISAB (Ionic Strength Adjustment Buffer) to a fixed volume of all standards and samples.

Each ISAB is carefully selected for each different ISE to ensure that the added ions do not interfere with the measurement but do have sufficient concentration to increase the overall Ionic strength to the desired level without diluting the solutions significantly.

Application methods available from EDT directION are available.

Specialist ISABs can also be used to equalize pH or remove interferents as required. For advice on these applications please contact our technical support team sales@edt.co.uk