Overview

Ion selective electrodes (ISE) are modern analytical tools that enable rapid and direct determination of ion activity in sample solutions. Together with a suitable ion meter or titrator, the ISE forms an affordable and versatile measuring system. Like the ph theory, the ISE theory is also based on the Nernst equation. ISE's approach is easy to understand and simple to apply in many situations.

Ion selective electrodes are used to measure the activity of the ions being measured. Ions must be dissolved in water. If the sample does not dissolve, it should be dissolved first using other methods to dissolve the ions in the solution. The color and turbidity of the sample usually do not interfere with the measurement. Ion chromatography (IC) and titration are alternative analytical methods for measuring ion activity. For IC, the sample solution needs to be transparent, the measured ion concentration is preferably in the ppm range, and the equipment cost is higher than ISE.

ISE methods are used in a variety of applications, such as chemical and pharmaceutical samples, as well as environmental monitoring, water quality testing, food and plants, which are very suitable for ISE analysis.

Cations suitable for ISE: ammonium, barium, calcium, cadmium, copper, lead, lithium, potassium, silver, sodium

Anions used in ISE: bromide, chloride, cyanide, fluoride, fluoroborate, iodide, nitrate, sulfide, thiocyanate?

How ion selective electrode work?

Ion selective electrodes are dividedd into two types: composite electrodes and half cells. In the case of a composite electrode, the measuring and reference electrodes are integrated into one electrode. The half-cell electrode consists only of ion-selective elements. In order to form a complete electrode system, a suitable reference electrode needs to be configured. The sensitive membrane element of ISE is an ion-selective membrane, which can generated different potentials under different ion concentration conditions. Therefore, there is a corresponding change in the potential difference between the ion-selective measurement electrode and the reference electrode, which can be measured using an ion meter.

This potential difference is directly proportional to the activity of the relevant ions in the solution. Ionic activity is related to the concentration and ionic strength of the sample solution. In everyday applications, ion concentration is tested rather than activity. commonly used concentration units are mol/L, mg/L or ppm.

Delfino focuses on the R&D and production of water quality analysis instruments. Its main products include pH ORP analyzer, conductivity analyzer, turbidity analyzer, COD analyzer, dissolved oxygen analyzer, ammonium analyzer, chlorine analyzer, etc. We have many different types of online ISE sensors, such as Fluoride ion electrode, chloride ion electrode, ammonium ion electrode, etc. If you are interested in the products, feel free to contact us!

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