Thermo Fisher Scientific Ion Selective Electrodes Silver - Manual (Page 6)

Silver/Silver Sulfide Electrode Instruction Manual
6
Electrode Slope Check (with ion meter)
(Check electrodes each day)
Using silver standards:
1. Prepare standard silver solutions whose concentrations vary by tenfold. Use either the
0.1M AgNO
3
or 1,000 ppm stock solutions. 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.
6.
Adjust the meter to the concentration of the standard and fix the value in the memory.
7.
Read the electrode slope according to the meter manufacturer's instructions. Correct
electrode operation is indicated by a slope of 90-100%. See the
TROUBLESHOOTING
section if the potential is not within this range.
Using sulfide stock solutions:
1. Prepare standard sulfide solutions whose concentrations vary by tenfold. Use the serial
dilution method and the weekly sulfide standard to prepare these solutions.
2.
To a 150 ml beaker, add 50 ml of the lower value standard, 25 ml of SAOB, and 25 ml of
distilled water. 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 a 150 ml beaker, add 50 ml of the higher value standard, 25 ml of SAOB, and 25 ml of
distilled water. Place the beaker on a magnetic stirrer and begin stirring at a constant rate.
Lower the electrode tips into the solution.
6.
Adjust the meter to the concentration of the standard and fix the value in the memory.