In-Situ TROLL 9500 Operators Manual User Manual
Page 125
120
TROLL 9500 Operator’s Manual
0095110 rev. 007 01/09
POTENTIAL INTERFERENCES
The following table shows concentrations of possible interfering ions
that cause 10% error at various levels of NO
3
–
.
SENSOR CARE AND HANDLING
SENSOR REMOVAL
Position the yoke of the sensor removal tool at the point
where the sensor meets the sensor block and pry the
sensor upward.
Avoid touching the membrane at the tip of the
sensor. Contaminants on the membrane can
change its properties and affect measurements.
MAINTENANCE/INSPECTION/CLEANING
As long as extreme pH and high organic solvent content is avoided,
the sensor should last for several months at room temperature.
Eventually some of the components will leach out, and this will affect
the response (detection limit and scope), but this can be compensated
through calibration.
If film buildup is visible on the membrane, rinse under a gentle stream
of clean water, or swish gently in a mild detergent solution, rinse well
with clean water, and shake to dry.
To avoid depletion of the reference solution, do not allow the sensor to
soak in pure water for more than a few minutes at a time.
The electrode is not customer-refillable.
STORAGE
Store the sensor immersed in 14 or 140 ppm N solution, depending
on usage requirements, rather than dry or in DI water.
REFERENCES
Eaton, A.D., L.S. Clesceri, E.W. Rice, and A.E. Greenberg, eds.,
Standard Methods for the Examination of Water and Wastewater,
21st edition, Washington, D.C.: American Public Health Associa-
tion, American Water Works Association, and Water Environment
Federation, 2005. Section 4500-NO
3
–
D. Nitrate Electrode Method.
EPA, Methods for Chemical Analysis of Water and Wastes,
EPA/600/4-79-020, revised March 1983. Method 350.3, Nitrogen,
Ammonia, Potentiometric, Ion Selective Electrode. Approved at 40
CFR Part 136.
Rundle, Chris C., A Beginners Guide to Ion-Selective Electrode
Measurements. Nico2000 Ltd., London, UK. On the web at www.
nico2000.net
sensor
removal
tool
Ion
100 ppm NO
3
–
10 ppm NO
3
–
1 ppm NO
3
–
ClO
4
–
0.01 0.001
0.0001
I
–
0.5
0.05
0.005
ClO
3
–
5 0.5 0.05
CN
–
10 1 0.1
Br
–
70
7 0.7
NO
2
–
70 7 0.7
HS
–
100
10 1
HCO
3
–
1000 100 10
CO
3
2–
2000 200 20
Cl
–
3000
300
30
H
2
PO
4
–
5000 500 50
HPO
4
2–
5000 500 50
PO
4
3–
5000 500 50
AcO
–
20,000
2000
200
F
–
60,000
6000
600
SO
4
2–
100,000
10,000
1000
SECTION 17: NITRATE