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Effective ion-selective electrodes are an important part of your electrochemistry toolkit. In addition to H+ ion selective probes, METTLER TOLEDO offers a wide range of half-cell and combined ion selective electrode types to meet your needs for measuring ions such as silver, fluoride, bromide, nitrate, cadmium, ammonia, chloride, lead, and more.
With high-quality materials and effective features, our modular combined and half-cell ion-selective electrode range is designed to offer you a complete reference system when working in industries including biomedical, environmental monitoring, mining and petroleum processing. Whether the species of interest is being determined in an aqueous solution or a more complex matrix such as wastewater, you achieve accurate results.
A PerfectION™ combined ion selective probe enables precision—no additional reference electrode required. The low-maintenance design helps to ensure a long lifetime, making these ion selective electrodes ideal for almost any application. An attached cable with either a BNC or LEMO plug ensures fast, secure connection to the instrument.
Our ion-selective half-cell ISE electrodes consist of a universal shaft plus an ion-specific module that can be quickly exchanged to measure different ion species. Simply choose the correct half-cell for your application to achieve easy readings for your species of interest.
The Click & Clear™ junctions of our PerfectION™ ion selective electrodes enable optimal electrolyte contact. They also offer you an effective mechanism for quick cleaning. A simple cap-click flushes and clears, while the junction is automatically reset when you release the cap. This helps to ensure stable, drift-free ion-selective electrode readings—even in dirty or viscous samples. Electrolyte refilling or replacement is also quick and easy.
Accuracy depends on more than your ion-selective electrode’s features. All components in an electrochemistry system must work together to provide reliable results. Our experts can help you select meters, solutions and services that complement your specific application needs.
We offer a variety of durable benchtop and portable meters. Our portfolio has options to meet your needs for compliance and routine measurements, and it includes economical models for those working under tight budgets.
Benchtop MetersPortable Meters
Choose from our ready-to-use ion calibration standards, ionic strength adjusters (ISAs) and electrolytes. With our ready-to-use calibration standards, no weighing or diluting is required, while our ISAs ensure you obtain accuracy from your ion selective electrode. The most common standards are available in concentrations of 10, 100 and 1000 mg/L (ppm).
Our pH Competence and Support Center (pH CSC) offers you easy access to dedicated application specialists for your pH, ORP, ion, conductivity, and DO measurements. These specialists provide know-how and collaborate with product management and development to help ensure a high degree of success in all your critical electrochemical analyses.
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All user manuals come with the necessary information about the short and long term storage of the respective sensor. Generally Ion Selective Electrodes should be stored dry for long term storage.
The response time depends on the type of ion as well as its concentration.
Whereas the relatively fast sensors for Na+ and F- feature response times of 1-3 minutes at higher concentrations, the response time increases to 5-10 minutes when measuring in the range of the lower detection limits.
The size of an ion has an important impact on the speed of a measurement. That is why most of the other ions take longer to be measured. Analysis of heavy metals such as Cu2+ or Cd2+ can even take 20-30 minutes when performed near the lower detection limit.
A gentle and constant stirring in ion measurement is crucial for achieving a stable signal as fast as possible. Stabilization is reached faster, when moving from a lower concentration to a higher one than going the inverse way. Therefore, it is recommended to always start with the lowest concentration when calibrating and measuring.
The potential of the sensor is measured at many different concentrations of the ion of interest. One draws a curve of these mV signals against the concentration (logarithmic). Normally, it is S-shaped: rather flat at very high and at very low concentrations, almost linear in-between. The specified detection limits are defined by the range in which the behavior is more or less linear. To make an ISE usable for a different range, one would have to change the membrane surface (larger for lower concentrations) or use a different ion-selective substance in the membrane.
A sodium selective electrode is a glass electrode very similar to a pH electrode. pH glass electrodes show a negligible alkali error, and amplification of the "alkali error" leads to sodium selective electrodes which respond only to changes in the sodium ion concentration at pH values above 7. Therefore the lifetime of a sodium ISE is similar to the lifetime of a pH electrode, and is influenced by a number of factors (e.g. elevated temperatures, extreme pH values, etc.).
