IOP 019A.1
Effective Date: 1/11/2017
Page 8 of 11
then pull apart the connectors.
IV.
pH sensor calibration
IMPORTANT: Exposure of an ammonium sensor to the pH buffers will cause extremely long
ammonium calibration times. If an ammonium sensor is installed, cover it with a tight rubber seal
or remove it and insert a port plug before calibrating the pH sensor.
A.
Press
Cal
. Select
None
. Highlight
ISE (pH)
and press
enter
. The message line will show
the instrument is “Ready for point 1”. The pH calibration allows up to six calibration
points.
B.
Place the sensor in a pH 7 buffer solution. The instrument should automatically recognize
the buffer value and display it at the top of the calibration screen. If the calibration value
is incorrect, the auto buffer recognition setting in the Sensor Setup menu may be
incorrect. If necessary, highlight the Calibration Value and press enter to input the correct
buffer value. After 5 minutes and once the pH and temperature readings stabilize,
highlight
Accept
Calibration
and press
enter
to accept the first calibration point. The
message line will then display “Ready for point 2”.
C.
Rinse and place the sensor in the second buffer solution. The instrument should
automatically recognize the second buffer value and display it at the top of the screen. If
necessary, highlight the Calibration Value and press enter to input the correct buffer
value. After 5 minutes and once the pH and temperature readings stabilize, highlight
Accept Calibration
and press
enter
to confirm the second calibration point. The
message line will then display ‘Ready for point 3” and you can continue with the 3
rd
calibration point if desired. If you do not wish to perform a 3rd calibration point, press
Cal
to complete the calibration.
V.
Ammonium sensor calibration
The calibration procedures for ammonium, nitrate, or chloride are similar to pH. The only
differences are the calibration solutions. If the ammonium sensor was capped in order to calibrate
the pH sensor, remove the cap before beginning the ammonium sensor calibration.
A.
Place the proper amount of 1 mg/L Ammonium standard into the pre-rinsed calibration
cup. Carefully immerse the sensor into the solution. Allow at least 1 minute for
temperature equilibration before proceeding.
B.
Press
Cal
. Select
None
. Highlight
ISE (Ammonium)
and press
enter
. The message line
will show the instrument is ready for the 1st calibration point. The instrument will
display the calibration value at the top of the screen. If necessary, highlight the
Calibration value and press enter to input the correct value. After 5 minutes and once the
ammonium and temperature readings stabilize, highlight
Accept
Calibration
and press
enter
to accept the first calibration point. The message line will then display “Ready for
point 2”.
C.
Rinse the sensor with clean water, then dry it before placing it in the 100 mg/L
calibration standard. Allow at least 5 minutes for temperature equilibration before
