YSI 6000UPG - Manual (Page 61)

4-12
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 which 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 which are
both as close as possible to the temperature of your environmental sample. In this procedure, the
NH
4
+
sensor is usually calibrated using solutions which 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 which 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 two calibration solutions, one 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
°
.
On selecting this option, you will be given the choice of 1-point, 2-point, or 3-point calibrations for
your nitrate (NO
3
- ) sensor. The procedures for calibration of the nitrate sensor are identical to
those in 7 above for the ammonium sensor, except that the calibrant values are in mg/L of NO
3
-N
instead of NH
4
-N.
On selecting this option, you will be given the choice of 1-point, 2-point, or 3-point calibrations for
your turbidity sensor.
The 1-point option is used only to zero the turbidity probe. Place the sonde in clear water with no
suspended solids, and input 0 NTU at the screen prompt. Press Enter and the screen will display
real-time readings which will allow you to determine when the turbidity readings have stabilized.
Press Enter after the readings have stabilized to confirm the calibration and zero the sensor. Then,
8. Nitrate
9. Turbidity