Oyster-10, V1.9 11/09
8
Troubleshooting an Electrode Problem
Symptom
Cause
Recommended Solution
Long response time or
reading drift
Clogged Junction
Soak in 4.07 M Potassium Chloride
(KCl) @ 60
o
C for 30 minutes. Replace
electrode if necessary.
Strong Alkaline
measurement
Soak in 0.1 M HCL overnight
Deteriorated Gel layer of
pH sensing membrane
Replace electrode
Protein coating on
electrode surface
Soak in 1 gm Pepsin dissolved in
100ml of 0.1 m HCL for 30 mins. or as
needed
Oil, paint, dyes, suspended
solids on sensor
Rinse electrode alternately with
materials solvent (briefly) then a
buffer 7.00
Organic solvents are
coating sensor
Organic mole fraction has to be less
than 50% to assure reasonable
readings. Limit time of measurement.
Keep probe in the 7.0 buffer between
readings.
Dehydrated membrane
Read solution for dry bulb below
Dry Bulb
Long term storage without
wetting
Soak electrode tip in wetting cap filled
with 1ml 7.00 buffer for 24 to 48 hours
Static Charge
Wiping electrodes
Rinse electrode in 7.0 buffer and blot.
Do no wipe electrode.
Same readings in
different buffers and
samples
Cracked or broken bulb
Replace electrode. Use bulb guard.
Avoid plunging electrode to bottom of
container and spinning bars. A wetting
cap will protect bulb between
measurements.
Erratic LCD display
Samples have low ionic
strength (lacks salt); e.g.
distilled, de-ionized, boiled,
lake water (high pressure)
For each 50 ml of sample add 1 drop
(50uL) of SAT.KCL No alteration in
pH will occur by inert KCL.
