Xylem 6-Series Multiparameter - Manual (Page 89)

Sondes Section 2
YSI Incorporated Environmental Monitoring Systems Operations Manual 2-83
When selecting ISE3-NH4+, you will be given the choice of 1-point, 2-point, or 3-point calibrations for
your ammonium (NH
4
+ ) sensor.
Select the 1-point option only if you are adjusting a previous calibration. If a 2-point or 3-point calibration
has been performed previously, you can adjust the calibration by doing a one point calibration. Immerse
the sonde in any solution of known ammonium concentration and press Enter. You will be prompted to
type in the NH
4
+ value (in mg/L of NH
4
-N) of the solution you are using. Press Enter again, and the screen
will display real-time readings that will allow you to determine when the NH4 + readings have stabilized.
Pressing Enter will confirm the calibration.
Select the 2-point option to calibrate the NH
4
+ probe using only two calibration standards that are both at
approximately the temperature of your environmental sample. In this procedure, the NH
4
+ sensor is usually
calibrated using solutions that contain 1 and 100 mg/L of NH
4
-N . Be certain that the calibration solution
and sensor are thermally equilibrated prior to entering NH
4
+ values.
To begin the calibration immerse the sonde in the 1 mg/L standard, press Enter, input the NH
4
-N value,
and again press Enter. The screen will display real-time readings that will allow you to determine when
the sensor has stabilized. Pressing Enter will confirm the first calibration. Following the instructions on
the screen, place the sonde in the second NH
4
+ standard, press Enter, input the correct concentration value,
again press Enter, and view the stabilization of the values on the screen in real time. After the readings
have stabilized, press Enter to confirm the calibration. Then, as instructed, press any key to return to the
Calibrate menu.
Select the 3-point option to calibrate the NH
4
+ probe using three calibration solutions, two at ambient
temperature and one at a temperature significantly different from ambient. The 3-point calibration method
should be used to assure maximum accuracy when the temperature of the media to be monitored cannot be
anticipated. The procedure for this calibration is the same as for a 2-point calibration, but the software will
prompt you to place the sonde in the additional solution to complete the 3-point procedure. Be certain that
the calibration solution and sensor are thermally equilibrated prior to proceeding with the calibration. The
recommended order of calibration standards is (1) 100 mg/L standard at ambient temperature, (2) 1 mg/L
standard at ambient temperature, and (3) 1 mg/L standard at a different temperature (usually lower) than
ambient. For best results, insure a temperature difference of at least 10 C  between the two 1 mg/L
standards.
NOTE: YSI strongly recommends the use of the 3-point protocol to ensure the best possible performance
from all ISE sensors (ammonium, nitrate, and chloride)
NITRATE
When selecting ISE4 NO3, you will be given the choice of 1-point, 2-point, or 3-point calibrations for your
nitrate (NO
3
- ) sensor. The procedure is identical to that for the ammonium sensor, except that the calibrant
values are in mg/L of NO
3
-N instead of NH
4
-N.
NOTE: YSI strongly recommends the use of the 3-point protocol to ensure the best possible performance
from all ISE sensors (ammonium, nitrate, and chloride)