YSI EXO ISE Ammonium Sensor
Features
- Measures NH4 in freshwater applications
- Depths not to exceed 17 meters (55 ft) or 25 psi
- 3 month warranty on sensing module
- Free ground shipping
- Expedited repair and warranty service
- Lifetime technical support
- More
The EXO ion-selective electrode (ISE) ammonium sensor uses a silver/silver chloride wire electrode in a custom filling solution. The internal solution is separated from the sample medium by a polymer membrane, which selectively interacts with ammonium ions. When the sensor is immersed in water, a potential is established across the membrane that depends on the relative amounts of ions in the sample and the internal solution. This potential is read relative to the Ag/AgCl reference electrode.
Ammonium is calculated from the pH, salinity, and temperature readings. If a pH sensor is not in use, the instrument will assume the sample is neutral (pH 7) for the calculation. If a conductivity sensor (salinity) is not in use, the instrument will use the salinity correction value entered in the ammonium sensor calibration screen for the calculation.
In The News
Total algae sensor is the newest addition to YSI's EXO sondes
Many algae sensors can detect Chlorophyll a or levels of blue-green algae. YSI’s new Total Algae Sensor can measure both at the same time. 
 “If you’re only looking at Chlorophyll a, you can miss a very big portion of total algae biomass,” said Tim Finegan, product manager. 
 The new sensor is an optional attachment to the company’s line of EXO sondes, which debuted earlier this year. It’s an optical probe and maintenance is limited to keeping the sapphire windows on the unit clean. 
 The Total Algae Sensor can be calibrated in two different ways, one for spot sampling and one for continuous sampling, which allows users to make sure readings are accurate for their specific monitoring applications.
Read MoreYSI's fDOM sensor sheds light on organic matter
The new YSI EXO Sonde expands monitoring capabilities for users compared to YSI’s the previous generation of sondes. One new feature for the EXO is a fluorescent dissolved organic matter probe that measures light-absorbing particles in water. 
 
The sensor is another attempt by YSI to provide instrumentation options to those in the waste water industry, or anyone interested in measuring dissolved organic matter alongside other parameters. 
 
YSI’s fDOM sensor detects only on a narrow wavelength range. “The wavelength at which (particles) absorb light optimally and then the wavelength that they emit, or fluoresce light optimally, is unique to that molecule,” said Rob Ellison, YSI EXO director of research and development, during a webinar on the fDOM sensor.
Read MoreYSI improves sonde technology with EXO
A new line of multiparameter sondes is making a splash in the water monitoring market. The recently introduced YSI EXO line offers simpler calibration, more rugged materials and a future-proof design. 
 
The new water quality sondes can measure temperature, conductivity, depth, dissolved oxygen, pH, ORP, total algae (chlorophyll and blue-green algae), turbidity and fluorescent dissolved organic matter. 
 
The EXO sondes carry Smart QC, which is a series of quality control checks that run automatically to help maintain calibration. Feedback from testing has confirmed that the checks cut down on wasted trips into the field due to setup or configuration errors.
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