Theory Of Operation - Hach NO3D sc User Manual

General Information

2.3 Theory of operation

The NO3D sc sensor utilizes ion-selective electrode technology to
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measure nitrate ions (NO ) in a waste water sample. Well-known
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interferences of temperature and chloride are compensated by
using appropriate built-in sensors. The reference electrode is a
differential pH technology and does not have direct contact with the
process and therefore, it is particularly stable against drift.
Ion-selective electrodes have a special membrane to which only a
specific type of ion can adhere. As a result an ion-specific potential
forms on the membrane surface. To be able to measure a potential
difference, a reference electrode is required, which is not affected
by the sample to be measured.
TM
CARTRICAL technology reduces cross-sensitivities by not only
calibrating each electrode individually but also calibrating all
3 electrodes to each other.
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