Hach-Lange NH4D sc Ammonium Sensor - Manual (Page 23)

23
Operation
4.6.2 Matrix correction overview
With the NH4D sc sensor, there are various options ( Table 1 ) for
correcting the measured value with laboratory reference values.
For the laboratory reference value, a sample is taken for laboratory
analysis and the measurement value at that time is stored.
Depending on the parameter set, the laboratory reference value of
the water sample is stored as ammonium nitrogen (NH
4
–N) or as
ammonium (NH
4
). This laboratory reference value replaces the
prior value measured by the sensor.
Table 1 Correction options for the NH4D sc sensor
Correction Option Application
MATX1
The most commonly used Matrix correction. It performs a 1 point matrix correction (offset
adjustment) for ammonium (
4.6.3.1 on page 24 ).
MATX1 K+
With the MATX1 K+ the ammonium value will be corrected as with the MATX1 and in addition the
potassium value can be corrected. This is necessary if a higher precision of the ammonium value is
required as the potassium value will interfere the ammonium measurement (
4.6.3.2 on page 24 ).
MATX2
Where there is a dynamic process with a large ammonium fluctuation (at least 1/2 decade between
the lowest and highest concentration)
1 , it is recommende to perform the MATX2 ( 4.6.3.3 on page
25 ).
MATX2 K+
Where there is a dynamic process with a large ammonium fluctuation (at least 1/2 decade between
the lowest and highest concentration)
1 and potassium value is to be corrected, it is recommended to
perform the MATX2 K+ ( 4.6.3.4 on page 26 ).
VALUE CORR
The ammonium and potassium displayed value and the ammonium laboratory value can be entered
for two points. This is a different way to perform a MATX2 Correction. Here, for two points, the
displayed ammonium and potassium values and the ammonium laboratory value are entered via an
input screen.
PREVIOUS CAL Activation of one of the last four matrix and value corrections performed.
FACTORY CAL
If the current sensor code is no longer available, average data for the sensor can be activated using
FACTORY CAL.
1 Example of a half decade: The ammonium nitrogen concentration moves between 1 and 5 mg NH
4
–N or
between 5 and 25 mg/l NH
4
–N.