Myron L 729II - Manual (Page 64)

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e. Sources of Error
Because sources of error are much the same as for pH. Though
the platinum surface will not break like the glass pH surface, its
protective glass sleeve can be broken. A surface film will slow the
response time and diminish sensitivity. It can be cleaned off with
IPA, detergent, or acid, as with the pH glass.
3. pH and ORP SENSOR CAUTIONS
Leaving high pH (alkaline) solutions in contact with the pH and /or
sensor for long periods of time can damage it. Samples containing
chlorine, sulfur, or ammonia can “poison” any pH electrode. Any
sample element which will reduce (add an electron to) silver, such
as cyanide, will attack the reference electrode. Fluorides in the
water will reduce the life of any pH sensor.
Our unique line of pH and ORP sensors are a nonrefillable
combination type featuring a porous liquid junction. It should not
be allowed to dry out in use or in storage. If it does, the sensor
can sometimes be rejuvenated by first cleaning the sensor with
isopropyl alcohol and rinsing well. Do not scrub or wipe the
sensor.
Then use one of the following methods:
1. Soak the sensor in a HOT salt solution ~60°C (140°F),
preferably potassium chloride (KCI) solution — HOT tap water
with table salt (NaCl) will work fine — and allow to cool. Retest.
Or
2. Soak the sensor in DI water and allow to stand for no more than
4 hours (longer can deplete the reference solution and damage
the glass bulb). Retest.
If neither method is successful, sensor must be replaced.
“Drifting” can be caused by a film on the pH sensor bulb. Isopropyl
alcohol may be used to clean the sensor. The sensor bulb is very
thin and delicate. Do not scrub or wipe the sensor.
Replacement sensors are available only from the Myron L
Company or its authorized distributors.