Thermo Scientific REDOX/ORP 9678BNWP User manual

Thermo Fisher Scientific
Environmental Instruments
Water Analysis Instruments
166 Cummings Center
Beverly, MA 01915 USA
Tel: [phone]
Toll Free: 800-225-1480
Dom. Fax: [phone]
Int’l. Fax: [phone]
www.thermo.com/water
User Guide
Redox/ORP
Electrodes

1Redox/ORP Electrode User Guide
Introduction
This user guide contains information on the preparation,
operation and maintenance of the Thermo Scientific Orion ORP
electrodes. These ORP electrodes combine a platinum redox
sensing electrode and a silver/silver chloride reference electrode
in one body.
The redox/ORP electrodes can be used to make direct
measurements of redox potentials or perform potentiometric
titrations. The ORP Triode electrodes have a built-in thermistor
for measuring temperature.
Epoxy Sure-Flow Combination Redox/ORP Electrodes,
Cat. No. 9678BNWP and 967800
The Sure-Flow junction prevents the electrode from clogging in
dirty, viscous or wastewater samples. The epoxy body is break-
resistant for rugged environments.
Glass Combination Redox/ORP Electrodes,
Cat. No. 9778BNWP and 9778SC
The glass body enables the electrode to be used in solutions
that contain organic solvents. Use the electrode in water,
wastewater, metal plating and organic solvent samples.
Epoxy Refillable ORP/ATCTriode,
Cat. No. 9180BNMD and 9180BN
The electrode includes a built-in temperature probe for
measuring ORP and temperature with one electrode. The
refillable design allows the electrode filling solution to be
changed in case of contamination or clogging.
Epoxy Low Maintenance ORP/ATCTriode,
Cat. No. 9179BNMD and 9179BN
The electrodes include a built-in temperature probe for
measuring ORP and temperature with one electrode. The
electrodes contain a gel reference solution, so no filling solution
is required.
Note: Redox/ORP electrodes are not designed for constant
current or amperometric titrations, such as Karl Fischer
moisture analysis.

2Redox/ORP Electrode User Guide
Required Equipment
1. Thermo Scientific Orion pH/mV meter, such as the 3-Star
pH meter, 4-Star pH/ISE meter, 4-Star pH/DO meter, 4-Star
pH/conductivity meter or 5-Star pH/ISE/DO/conductivity
meter.
ORP electrodes can be used on any pH/mV meter with a
BNC or U.S. standard connection. The electrodes can also
be used on meters with a variety of inputs when an adapter
cable is used. Visit www.thermo.com/water for details.
Refillable ORP Triodes have temperature connectors that
are compatible with specific meters, refer to the list below.
2. Thermo Scientific Orion ORP electrode.
• The 9180BNMD and 9179BNMD ORP/ATC Triode
electrodes have a temperature connector that is
compatible with the Star Series meters.
• The 9180BN and 9179BN ORP/ATC Triode electrode
have a temperature connector that is compatible with
the A+ Series meters.
3. ORP electrode filling solution. Use Cat. No. 900011
filling solution for samples that have a total ionic strength
greater than 0.2 M. Use Cat. No. 900001 filling solution for
samples that have a total ionic strength less than 0.2 M.
ORP electrode filling solution is not required if using a
9179BNMD or 9179BN low maintenance ORP/ATC Triode
4. ORP standard, Cat. No. 967901 or 967961.
ORP standard is highly recommended to ensure accurate
ORP measurements.
5. Beakers, plastic or glass.
6. Magnetic stirrer or Orion stirrer probe, Cat. No. 096019.
The stirrer probe can be used with 3-Star, 4-Star and 5-Star
benchtop meters.
7. Distilled or deionized water.

3Redox/ORP Electrode User Guide
Sample Requirements
Electrodes with an epoxy body should only be used in aqueous
solutions.
Electrodes with a glass body may be used in non-aqueous
solutions and solutions that contain organic solvents.
The ORP electrodes contain a silver/silver chloride (Ag/AgCl)
reference that may become clogged in solutions that contain
silver complexing or binding agents such as TRIS, proteins and
sulfides. Frequent cleaning may be required when measuring
solutions that contain these agents. Proteins cause the
additional problem of coating the electrode, so extra care should
be taken to keep the electrode clean while measuring samples
that contain proteins.

4Redox/ORP Electrode User Guide
Electrode Preparation
Electrode Preparation for Refillable Electrodes
1. Remove the protective shipping cap from the sensing
element and save the cap for storage.
2. Clean any salt deposits from the exterior of the electrode by
rinsing with distilled water.
3. Uncover the filling hole by removing the tape and then add
electrode filling solution, Cat. No. 900011, to the electrode.
To maintain an adequate flow rate, the level of filling
solution must always be above the reference junction and
at least one inch above the sample level. The filling hole
should be open whenever the electrode is in use.
4. For Sure-Flow electrode only, wet the junction by pressing
down on the electrode cap to let a few drops of the filling
solution flow out of the electrode and then replenish any
lost solution.
5. Shake the electrode downward (similar to a clinical
thermometer) to remove air bubbles.
6. Connect the electrode to the meter.
Note: The fill hole must be open when the electrode is in use.
Electrode Preparation for Gel-Filled Electrodes
1. Remove the protective shipping cap from the sensing
element and save the cap for storage.
2. Clean any salt deposits from the exterior of the electrode by
rinsing with distilled water.
3. Shake the electrode downward (similar to a clinical
thermometer) to remove air bubbles.
4. Connect the electrode to the meter.

5Redox/ORP Electrode User Guide
filling hole
Ag/AgCl
internal
reference
filling
solution
chamber
ceramic
reference
junction
sensing
element
fill hole
AgAgCl
internal
reference
reference
filling solution
chamber
Sure-Flow
junction
sensing
element
Figure 1– Refillable ORP Electrode
filling hole
Ag/AgCl
internal
reference
filling
solution
chamber
ceramic
reference
junction
sensing
element
fill hole
AgAgCl
internal
reference
reference
filling solution
chamber
Sure-Flow
junction
sensing
element
Figure 2– Sure-Flow Refillable ORP Electrode

6Redox/ORP Electrode User Guide
Electrode Calibration
ORP readings can be reported using the absolute mV values
or the EHmV values. EHmV values give the corresponding
mV values that would be obtained using a Standard Hydrogen
Electrode (SHE), also known as the Normal Hydrogen Electrode
(NHE). Orion ORP standard, Cat. No. 967901 or 967961, allows
operators to correlate measurements to the EHmV value with
an Orion ORP electrode.
The relative mV mode can be used to calibrate the ORP
electrode so the electrode reads the EHmV values in samples.
When an ORP electrode is calibrated to read EHmV values, the
resulting sample readings can be compared among multiple
meter and electrode systems.
Note: If the meter can perform an automatic ORP calibration
using an EHmode, refer to the meter user guide for detailed
instructions on the meter calibration procedure.
1. Set the meter to the relative millivolt mode. Refer to the
meter user guide for detailed instructions.
2. Place the ORP electrode in ORP standard, Cat. No. 967901
or 967961.
3. Set the meter to the EHmV value of the ORP standard at
the measured temperature using the information in Table 1.
Table 1– ORP Standard Values
Absolute mV values may vary by ± 60 mV
Temperature
(°C)
EHValue
(mV)
Absolute Value
with Cat. No.
900011 Filling
Solution (mV)
Absolute Value
with Cat. No.
900001 Filling
Solution (mV)
0 438 218 176
1 437 218 176
2 437 218 176
3 436 218 176
4 435 218 176
5 435 218 176
6 434 218 176
7 433 218 176
8 433 218 175
9 432 219 175

7Redox/ORP Electrode User Guide
Temperature
(°C)
EHValue
(mV)
Absolute Value
with Cat. No.
900011 Filling
Solution (mV)
Absolute Value
with Cat. No.
900001 Filling
Solution (mV)
10 431 219 175
11 430 219 175
12 430 219 175
13 429 219 175
14 428 219 175
15 428 219 175
16 427 219 174
17 426 219 174
18 425 219 174
19 424 219 174
20 424 219 174
21 423 219 174
22 422 219 174
23 421 219 173
24 420 220 173
25 420 220 173
26 419 220 173
27 418 220 173
28 417 220 172
29 416 220 172
30 415 220 172
31 414 220 172
32 413 220 172
33 412 220 171
34 412 220 171
35 411 220 171
36 410 220 171
37 409 220 171
38 408 220 170
39 407 220 170
40 406 220 170
41 405 220 170
42 404 220 169
43 403 220 169
44 402 220 169
45 401 220 169
46 400 220 168
47 399 220 168
48 398 220 168
49 397 220 168
50 396 220 167

8Redox/ORP Electrode User Guide
Measurement Techniques
• Always use fresh ORP standard for calibration.
• If the electrode is refillable, remove the filling hole cover
during measurements to ensure a uniform flow of filling
solution.
• Between measurements, thoroughly rinse the electrode
with distilled water. Gently shake the electrode after rinsing
to prevent solution carryover and then blot the electrode
dry with a lint-free tissue.
• Stir all standards and samples at a uniform rate.
• Place a piece of insulating material, such as Styrofoam or
cardboard, between the magnetic stirrer and beaker to
prevent measurement errors from the transfer of heat to
the sample.
• Allow all standards and samples to come to room
temperature for precise measurements.
• If the electrode is used in dirty or viscous samples or the
electrode response becomes sluggish, empty the electrode
completely and hold the junction under running water.
Empty any water from the electrode and refill it with fresh
electrode filling solution.
• If a Sure-Flow electrode is used in dirty or viscous samples
or the electrode response becomes sluggish, empty the
electrode completely and hold the junction open under
running water. Empty any water from the electrode and
refill it with fresh electrode filling solution. Press down on
the electrode cap to let a few drops of the filling solution
flow out of the electrode and then replenish any lost
solution.
• Make sure the electrode filling solution is appropriate
for the sample. Use Cat. No. 900011 filling solution for
samples that have a total ionic strength greater than 0.2 M.
Use Cat. No. 900001 filling solution for samples that have a
total ionic strength less than 0.2 M.