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Cleaning Procedure
Use diagnostic messages to aid pH electrode troubleshooting. Several cleaning solutions are
available:
• General – Soak in Hanna Instruments HI7061 or HI8061 General Cleaning Solution for
approximately ½ hour.
• Protein –Soak in Hanna Instruments HI7073 or HI8073 Protein Cleaning Solution for
15 minutes.
• Inorganic – Soak in Hanna Instruments HI7074 Inorganic Cleaning Solution for
15 minutes.
• Oil/grease – Rinse with Hanna Instruments HI7077 or HI8077 Oil and Fat Cleaning
Solution.
Note: After performing any of the cleaning procedures, rinse the electrode thoroughly with
distilled water, refill the reference chamber with fresh electrolyte (not necessary for gel-filled
electrodes) and soak the electrode in HI70300 or HI80300 Storage Solution for at least
1 hour before taking measurements.
Temperature Correlation For pH Sensitive Glass
Verify the temperature range by reading the limits on electrodes cap. The pH electrode’s life also
depends on the temperature that is used. If constantly cycled between two temperatures, the life of
the electrode is drastically reduced.
Alkaline Error
High concentrations of sodium ions interfere with readings in alkaline solutions. The pH at which the
interference starts to be significant depends upon the composition of the glass. This interference is
called alkaline error and causes the pH to be underestimated. Hanna Instruments’s glass formulations
have the indicated characteristics. Sodium Ion error for various glass types at ambient temperature:
MAINTENANCE
Alkali Error with 0.1 mol /L Na
+
pH GP HT LT
12.5 0.11 0.05 0.28
13.0 0.23 0.11 0.35
13.5 0.35 0.16 0.45
14.0 0.48 0.20 0.54
Alkali Error with 1.0 mol/L Na
+
pH GP HT LT
11.5 0.11 0.01 0.46
12.0 0.21 0.06 0.62
12.5 0.32 0.11 0.79
13.0 0.43 0.15
13.5 0.45 0.21
14.0 0.65 0.27
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