Thermo Fisher Scientific Ion Selective Electrodes Silver - Manual (Page 5)

Instruction Manual Silver/Silver Sulfide Electrode
5
GENERAL PREPARATION
Electrode Preparation
Remove the rubber caps covering the electrode tips and the rubber insert covering the filling hole of
the reference electrode. Fill the combination electrode or the reference electrode with the filling
solution shipped with the electrode to a level just below the fill hole. No preparation is required for
a sealed reference electrode. Connect the electrodes to the proper terminals as recommended by the
meter manufacturer.
Electrode Slope Check (with pH/mV meter)
(Check electrodes each day)
Using silver standards:
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
mV mode, lower the electrode tips into the solution.
2.
Using a pipet, add 1 ml of 0.1M or 1,000 ppm silver standard to the beaker. When the
reading has stabilized, record the millivolt reading.
3.
Using a pipet, add 10 ml of the same silver standard used above to the beaker. When the
reading has stabilized, record the millivolt reading.
4.
Determine the difference between the two readings. A difference of 57±2 mV indicates
correct electrode operation, assuming the solution temperature is between 20o and 25oC.
See the
TROUBLESHOOTING section if the potential change is not within this range.
Using sulfide stock solutions:
1. To a 150 ml beaker, add 50 ml of distilled water and 50 ml of SAOB solution. Place the
beaker on a magnetic stirrer and begin stirring at a constant rate. After assuring that the
meter is in the mV mode, lower the electrode tips into the solution.
2.
Using a pipet, add 1 ml of weekly standard sulfide solution to the beaker. When the
reading has stabilized, record the millivolt reading.
3.
Using a pipet, add 10 ml of weekly standard sulfide used above to the beaker. When the
reading has stabilized, record the millivolt reading.
4.
Determine the difference between the two readings. A difference of 26±2 mV indicates
correct electrode operation, assuming the solution temperature is between 20o and 25oC.
See the
TROUBLESHOOTING
section 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.