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7. RECONDITIONING
When reconditioning is required due to electrode aging (see
Helpful Operating Techniques, Part 9), the following
chemical treatments can be tried. They are presented in the
order of the severity of their attack on the pH glass and may
not improve ( and in some case actually further deteriorate )
electrode performance.
Note :
Use proper precautions when handling these
hazardous chemicals. Ammonium bifluoride and HF
(hydrofluoric acid) are extremely hazardous and
should only be used by qualified personnel.
1)Immerse the electrode tip in 0.1N HCL for 15 seconds,
rinse in tap water and then immerse tip in 0.1N NaOH
for is seconds and rinse in tap water. Repeat this
sequence three times and then recheck the electrode
performance. If performance has not been restored, try
Step 2.
2)Immerse the tip in a 20% solution of NH4F.HF
(ammonium bifluoride) for 2 or 3 minutes, rinse in tap
water and recheck performance. If performance has not
been restored, try Step 3.
3)Immerse electrode tip in 5% HF for 10 to 15 seconds,
rinse well in tap water, quickly rinse in 5N HCL, rinse well
in tap water and recheck performance. If performance
has not been restored it is time to get another epoxy
body, sealed reference combination pH electrode.
5
0701-PE21
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