eutech-instruments cadmium epoxy User Manual
Cadmium Electrode
Instruction Manual
4
dissolve the solid. Fill to the mark with distilled water, cap, and upend several times to
mix the solution.
mix the solution.
GENERAL PREPARATION
Electrode Preparation
Remove the rubber caps covering the electrode tips and the rubber insert covering the filling hole of
the cadmium combination electrode or 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 the
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.
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 1,000 ppm cadmium standard to the beaker.
When the reading has stabilized, record the mV reading.
When the reading has stabilized, record the mV reading.
3.
Using a pipet, add 10 ml of the standard used above to the beaker. When the reading has
stabilized, record the mV reading.
stabilized, record the mV reading.
4.
Determine the difference between the two readings. The electrode is operating correctly if
the mV potential has changed 27±2 mV, assuming the temperature is between 20
the mV potential has changed 27±2 mV, assuming the temperature is between 20
o
and
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.
10.
Electrode Slope Check (with ion meter)
(Check electrodes each day)
1.
Prepare standard cadmium solutions whose concentrations vary be tenfold. Use either the
0.1M or 1,000 ppm standard and the serial dilution method for this preparation.
0.1M or 1,000 ppm standard and 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 the 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.
beaker on the 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.
according to the meter manufacturer's instructions.
4.
Rinse the electrodes with distilled water and blot dry.