YSI ADV6600 - Manual (Page 65)

Section 4. Calibration and Diagnostics
ADV6600
Y S I
Environmental
Page 55
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 NH
4
+ sensor is usually calibrated
using solutions that contain 1 and 100 mg/L of ammonium-nitrogen (NH
4
-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 ammonium-nitrogen (NH
4
-N) standard at ambient temperature
2. 1 mg/L ammonium-nitrogen (NH
4
-N) standard at ambient temperature
3. 1 mg/L ammonium-nitrogen (NH
4
-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 ammonium standard to the calibration cup to ensure that the ammonium, pH, and
temperature sensors are completely covered. Allow at least 1 minute for temperature
equilibration before proceeding. (Allow at least five minutes for the third, chilled standard in a
3-point calibration.)
3. From the Calibrate menu, select ISE NH
4
+ to access the ammonium calibration choices and
select either a 1-point, 2-point, or 3-point calibration.
4. Input the value of the first standard at the prompt.
5. Press Enter and the current values of all enabled sensors will appear on the screen and change
with time as they stabilize in the solution. Observe the readings under NH4
+ and when they
show no significant change for approximately 30 seconds, press Enter. The display will
indicate if the calibration is accepted.
6. Press Enter again, as instructed on the screen. If a 2- or 3-point calibration was chosen, rinse
the sonde in deionized or distilled water and dry the sonde before proceeding with the next
ammonium standard, following the same steps as outlined above.
Ammonium sensors generally drift more than pH sensors. To check for this drift, place the probe in
one of your standards at the end of each deployment.
Ammonium standards are good growth media for a variety of organisms. This growth can
significantly reduce the nitrogen content of your standards, an effect that is particularly important
for the 1 mg/L solution. It is best to use new standards for each deployment, but if you decide to
save your solutions for reuse, we recommend refrigerated storage to minimize the growth of these
organisms.