Instruction Manual
Potassium Electrode
8
5.
Rinse the electrode tip(s) 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 tip(s) into the solution.
8.
Adjust the meter to the concentration of the potassium 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 electrode(s) into a 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 tip(s) in the solution and wait for the reading to stabilize. Read the
concentration directly from the meter display.
12. The electrodes should be re-calibrated every 1-2 hours. Simply repeat Steps 2-8 (2-9)
above.
Low Level Potassium Determination (using a standard pH/mV meter)
This procedure is recommended for solutions with ionic strengths less than 1.0 x 10-2M. If the
solution is high in ionic strength, but low in potassium, use the same procedure, but prepare a
calibration solution with a composition similar to the sample.
1.
Using 2 ml of stock ISA, dilute to 100 ml with distilled water.
2.
Dilute 1 ml of the 0.1M standard to 100 ml to prepare a 1.0x10
-3
M standard solution for
measurements in moles per liter. Dilute 10 ml of the 1,000 ppm standard to 100 ml to
prepare a 100 ppm standard solution for measurements in ppm.
3.
To a 150 ml beaker, add 100 ml of distilled water and 1 ml of low level ISA. Place the
beaker on the magnetic stirrer and begin stirring at a constant rate.
4.
Place the electrode tip(s) in the solution. Assure that the meter is in the mV mode.
5.
Add increments of the 1.0x10
-3
M or 100 ppm standard as given in Table 2 below.
6.
After the reading has stabilized, record the mV reading after each addition.