117
TROLL
9500
Operator’s Manual
0095110 rev. 007 01/09
s
Single-point
calibration. After the initial three-point bithermal cali-
bration has established the sensor slope, offset, and isopotential
point, a single-point calibration may be used with good results to
adjust the offset on a daily basis.
CALIBRATION SOLUTIONS
Potassium nitrate (KNO
3
) solutions certified to N.I.S.T. standards are
supplied in the In-Situ Nitrate Calibration Kits:
14.0 ppm as N
140 ppm as N
1400 ppm as N
Specialized calibration kits are available for calibrating the nitrate sen-
sor for low-range and high-range measurements:
Low range: two quarts each 14.0 ppm and 140 ppm
High range: two quarts each 140 ppm and 1400 ppm
RECOMMENDED CALIBRATION FREQUENCY
Ion-selective electrodes are inherently unstable and drift is quite
normal. To achieve the most accurate sensor response, we recom-
mend a complete three-point bithermal calibration once a week, with a
single-point calibration daily or after 4-6 hours of use.
PREPARING TO CALIBRATE
You will need:
s -042/,,WITHTHEHYDRATEDNITRATESENSORINSTALLEDANDSEN
-
sors o0r plugs in the other sensor ports
s #AL#UP
s /NETWOORTHREENITRATECALIBRATIONSOLUTIONSSELECTEDFORTHE
range you expect to measure. When performing a multi-point
calibration, begin with the lowest-concentration solution
s &ORATHREEPOINTBITHERMALCALIBRATIONATEMPERATUREBATHORA
container of ice large enough to hold the Cal Cup (and stirrer, if
used).
s 3TIRRER5SEASTIRRERDURINGCALIBRATIONIFITWILLALSOBEUSEDINTHE
field—for example, in stagnant or very slowly moving water. The
MORECLOSELYCALIBRATIONCONDITIONSREmECTlELDCONDITIONSTHEMORE
successful the calibration. For more information on the stirrer, see
“Stirring” in Section 10.
NITRATE CALIBRATION PROCEDURE
1. Rinse the Cal Cup and front end of the MP
TROLL 9500 in clean water. Shake to dry.
For best results, follow this with a rinse in a
portion of the selected calibration solution.
Discard the rinse solution.
2. Insure the black PVC base (or the stirrer) is
attached to the Cal Cup, and fill the Cal Cup
to the fill line with the selected calibration solu-
tion.
s "EGINWITHTHELOWESTCONCENTRATIONWHEN
performing a multi-point calibration.
s 7ITHAFULLCOMPLEMENTOFSENSORSINSTALLED
use the lower line as a guide.
s 7ITHORREMOVABLESENSORSINSTALLEDlLL
to the upper line.
3. Insert the front end of the MP TROLL 9500
into the open end of the Cal Cup. Thread the
Cal Cup onto the body until seated against the
o-ring, then back off slightly to avoid overtight-
ening.
To stabilize the instrument, you may wish to use a calibration stand
or other support.
4. Connect the MP TROLL 9500 to a PC and establish a connection
in Win-Situ 4 or Pocket-Situ 4. Win-Situ screens are illustrated
here. The Pocket-Situ interface is similar, with the Navigation tree
at the top of the screen and the Information pane below it.
5. Select the MP TROLL 9500 in the Navigation tree.
The software will automatically detect and display the installed sen-
sors. If one or more sensors is installed in the wrong port, an error
message will be displayed. Simply remove the sensor and install it
in the correct position, then “refresh” the device before continuing.
SECTION 17: NITRATE
3
Cal Cup
Stirrer
(optional)