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109117-1 Rev. A, 10/96
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3.1 Basic Theory (cont)
Temperature is also an important consideration when measuring
pH. It affects the electrode slope. ATC probes are recommended
so that the slope can be corrected for temperature. There are
many other factors that affect pH.
Further information on pH theory and the factors that affect the
ability to do accurate pH readings is included in ‘Guide to pH
Measurement’.
3.2 Operating Hints
This section gives some brief operating hints and good laboratory
practices to help assure trouble free pH measurements.
1. New electrodes (or electrodes that have been in storage)
should be conditioned in one inch (25mm) of pH 7.0 or 4.0
buffer for several hours prior to their use. Make sure that
the wetting cap has been removed from the tip of the
electrode.
2. Always remove the wetting cap and fill hole plug during
calibration and measurements. Replace the fill hole plug
when done.
3. Calibrate the electrode daily. Though a 1 point calibration
may be suitable for some applications, we recommend that
a 2 point calibration (that brackets the expected pH range)
be performed.
4. Be aware that if you are measuring hot or cold samples
without the use of an ATC probe, the values displayed are
not accurate. You should be calibrating and measuring at
room temperature.
5. When transferring from one sample to another, always
rinse the electrode with distilled water and blot dry.
Handle the electrode carefully and do not use it as a
stirring rod.
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