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titration, immediately wash off the electrode with distilled water and replace it in the storage
buffer.
e)
To prevent contamination of solutions, always wash the electrode with distilled water and
gently dry it with a kimwipe when moving the electrode to a different solution (including the
storage buffer).
f)
The pH meter works best if it is kept plugged in continuously.
2.
Calibration Procedure
The pH meters available are made by different manufacturers. The calibration procedure varies
slightly for the different models.
a)
Fisher Scientific Accumet pH meters
These meters must be set to STANDBY whenever the electrode will be moved from one
solution to another.
i)
Measure the temperature of the solution and set the pH meter to the same temperature using the
temperature adjustment knob (generally it will be room temperature, 20-22
C).
ii)
Rinse the electrode with distilled water and dry it with a kimwipe tissue.
iii)
Using the standard buffer of pH 7.00, turn to “pH” and set the meter display to 7.00 using the
“standardize knob”.
iv)
Rinse and dry the electrode.
v)
Using the standard buffer of pH 4.00, turn to “pH” and set the meter display to 4.00 using the
“slope knob”.
vi)
Rinse and dry the electrode and store it in the “storage buffer” until required.
b)
VWR Scientific pH meter, Model 8000
i)
Press “MODE” key to move the pH meter from the “standby” position.
ii)
Press “Cal” key to initiate calibrations sequence. CAL is displayed for 2 seconds, then SLP is
displayed for 2 seconds.
iii)
The display will show the calibration mode, pH 7-4. Press “yes” to accept this calibration
mode.
iv)
pH 7 will be displayed for two seconds. Rinse and dry the electrode, then immerse the
electrode in pH 7.00 standard buffe®. The pH meter is calibrated for pH 7.00 when the
ready light comes on. Press “yes” to accept the calibration.
