Instruction Manual
Iodide Electrode
4
GENERAL PREPARATION
Electrode Preparation
Remove the rubber caps covering the electrode tips and the rubber insert covering the filling hole of
the combination electrode or of the reference electrode. Fill the reference electrode or the
combination electrode with the filling solution shipped with the electrode to a level just below the
fill hole. No preparation is required with a sealed reference electrode.
Connect the electrodes to the proper terminals as recommended by the meter manufacturer.
Electrode Slope Check (with a pH/mV meter)
(Check electrodes each day)
1.
To a 150 ml beaker, add 100 ml of distilled water and 2 ml of ISA. Place the beaker on a
magnetic stirrer and begin stirring at a constant rate. After assuring that the meter is in the
millivolt mode, lower the electrode tips into the solution.
2.
Using a pipet, add 1 ml of either the 0.1M or the 1,000 ppm standard to the beaker. When
the reading is stable, record the mV reading.
3.
Using a pipet, add 10 ml of the same standard used above to the beaker. When the reading
has stabilized, record the mV reading.
4.
Determine the difference between the two readings. The electrode is operating correctly if
the mV potential has changed by a difference of 57±3 mV, assuming the solution
temperature is 25
o
C. See the
TROUBLESHOOTING
sections if the potential change is not
within this range.
Slope is defined as the change in potential observed when the concentration changes by a factor of
10.
Electrode Slope Check (with an ion meter)
(Check electrodes each day)
1.
Prepare standard iodide solutions whose concentrations vary by tenfold. Use either the
0.1M or the 1,000 ppm iodide standard. Use the serial dilution method for this preparation.
2.
To a 150 ml beaker, add 100 ml of the lower value standard and 2 ml of ISA. Place the
beaker on a magnetic stirrer and begin stirring at a constant rate. Lower the electrode tips
into the solution. Assure that the meter is in the concentration mode.
3.
Adjust the meter to the concentration of the standard and fix the value in the memory
according to the meter manufacturer's instructions.
4.
Rinse the electrodes with distilled water and blot dry.
5.
To another 150 ml beaker, add 100 ml of the higher value standard and 2 ml of ISA. Place
the beaker on a magnetic stirrer and begin stirring at a constant rate. Lower the electrode
tips into the solution.