YSI ADV6600 - Manual (Page 66)

Section 4. Calibration and Diagnostics
ADV6600
Y S I
Environmental
Page 56
The ammonium sensor should not be exposed to pH calibration buffers. If accidentally exposed, the
ammonium readings will be erratic and take longer to stabilize. To restore function of the
ammonium sensor, soak the probe in 100 mg/L standard for a few minutes to several hours (or
overnight). Perform a new calibration and pay careful attention that ammonium readings are stable.
CAUTION: The ammonium membrane module is for use only at depths less than 50 feet (15.2
meters). Use of the probe at greater depths is likely to permanently damage the sensor.
4-6.8. Nitrate
When selecting to calibrate Nitrate, you will be given the choice of a 1-point, 2-point, or 3-point
calibration. The temperature response of ion selective electrodes is not as predictable as that of pH
sensors. Therefore, be sure to carry out a 3-point calibration the first time you use the probe. This
will provide a default setting for the effect of temperature on your particular sensor. After this
initial calibration, you can use the less time-consuming 2-point and 1-point routines to update the 3-
point calibration. However, it is strongly recommended to perform a new 3-point calibration after
each deployment of 30 days or longer.
A 1-point calibration is used to adjust a previous calibration, using any solution of known
ammonium concentration.
A 2-point calibration is performed using two calibration standards that are both at approximately the
temperature of your environmental sample. In this procedure, the NO
3
-
sensor is usually calibrated
using solutions that contain 1 and 100 mg/L of nitrate-nitrogen (NO
3
-N).
A 3-point calibration assures maximum accuracy when the temperature of the media to be
monitored cannot be anticipated. This procedure utilizes three calibration solutions, two at ambient
temperature and one at a temperature significantly different from ambient. The recommended order
of calibration standards is:
1. 100 mg/L nitrate-nitrogen (NO
3
-N) standard at ambient temperature
2. 1 mg/L nitrate-nitrogen (NO
3
-N) standard at ambient temperature
3. 1 mg/L nitrate-nitrogen (NO
3
-N) standard at a different temperature (usually lower)
than ambient. For best results, ensure a temperature difference of at least 10 C
°
between the second and third standards.
Calibration:
1. Attach the ADV6600 to a ring stand in an inverted position with the clean, dry calibration
cup attached.
2. Add enough nitrate standard to the calibration cup to ensure that the nitrate, pH, and
temperature sensors are completely covered. Allow at least 1 minute for temperature