Thermo Fisher Scientific Ion Selective Electrodes Silver - Manual (Page 10)

Silver/Silver Sulfide Electrode Instruction Manual
10
2. Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate.
Assure that the meter is in the concentration mode.
3. Lower the electrode tips into the solution.
4.
Adjust the meter to the concentration of the silver standard and fix the value in the memory
according to the meter manufacturer's instructions after stabilization of the reading.
5.
Rinse the electrodes with distilled water and blot dry.
6.
Place the more concentrated solution on the magnetic stirrer and begin stirring at a
constant rate.
7.
Lower the electrode tips into the solution.
8.
Adjust the meter to the concentration of the silver standard and fix the value in the memory
according to the meter manufacturer's instructions after stabilization of the reading.
9.
For low level measurements, place the rinsed, dried electrodes into the solution containing
100 ml of distilled water and 2 ml of ISA. After stabilization, fix the blank value in the
meter according to the meter manufacturer's instructions.
10. Place 100 ml of the sample and 2 ml of ISA in a 150 ml beaker, place it on the magnetic
stirrer, and begin stirring.
11. Immerse the electrode tips in the solution and wait for the reading to stabilize. Read the
concentration directly from the meter display.
12. The calibration should be checked every two hours. Assuming no change in ambient
temperature, place the electrode tips in the first silver standard. After the reading has
stabilized, compare it to the original reading in Step 4 above. A reading differing by more
than 0.5 mV or a change in the ambient temperature will necessitate the repetition of Steps
2-8 (9) above. The meter should be re-calibrated daily.
Direct Measurement of Sulfide (using a pH/mV meter)
1. By serial dilution of the weekly standard, prepare three standard sulfide solutions.
Measure out 50 ml of each standard into individual 150 ml beakers and add 25 ml of
SAOB and 25 ml of distilled water to each.
2.
Place the most dilute solution on the 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.
When the reading has stabilized, record the mV reading.
3.
Place the midrange sulfide standard on the magnetic stirrer and begin stirring. After rinsing
the electrodes with distilled water, blot dry and immerse the electrode tips in the solution.
When the reading has stabilized, record the mV reading.