Refillable Ag/AgCl pH Electrode User Guide
Troubleshooting
Follow a systematic procedure to isolate the problem. The pH
measuring system can be divided into four components for ease
in troubleshooting: pH meter, electrode, sample/application
and technique.
pH Meter
The meter is the easiest component to eliminate as a possible
cause of error. Thermo Scientific Orion pH meters include
an instrument checkout procedure and shorting cap for
convenience in troubleshooting. Consult the pH meter user
guide for directions.
Electrode
To test electrode operation:
1. Connect the electrode to a working meter that has a mV
measuring mode.
2. Set the meter to the mV measuring mode.
3. Rinse the electrode with distilled water and then insert the
electrode into fresh pH 7 buffer.
4. When the reading is stable, record the mV value of the
pH 7 buffer. The mV value should be -30 to +30 mV.
5. Rinse the electrode with distilled water and then insert the
electrode into fresh pH 4 buffer.
6. When the reading is stable, record the mV value of the
pH 4 buffer. The mV value should be +150 to +210 mV.
7. Calculate the absolute mV difference between the two
buffers. The mV difference should be 160 to 180 mV. The
actual mV values will change as the electrode ages, but the
mV difference between the two buffers should always be
160 to 180 mV.
If the electrode fails this procedure, clean the electrode
thoroughly as directed in the
Electrode Maintenance
section.
If the electrode response is slow or drifting, drain and refill the
electrode with fresh filling solution, Cat. No. 900011. Replace
the electrode if cleaning and maintenance fail to rejuvenate it.
Summary of Contents for 9101BN
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