Teledyne Analytical Instruments LXT-380, Instructions Manual

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LXT-380 Universal Transmitter SP3X Sensors
Teledyne Analytical Instruments
63
8.3.6 PION ELECTRODE CARTRIDGE CLEANING
Ion selective electrodes require periodic service. Weekly checks
should be performed to assure the accuracy of the measurement.
The ion selective crystal that senses the ion concentration can
become sluggish in response due to coating or reactions with the process
solution. Periodic cleaning or polishing will minimize drift and maintain
the sensors response.
CLEANING
The solid state crystal based electrodes, bromide, chloride, copper,
cyanide, fluoride, silver, sulfide are fairly robust and can be cleaned with
alcohols, detergents or dilute acids to remove coatings caused by greases,
oils or films. A soft tooth brush or paper towel should be used to remove
stubborn coatings. Do not clean with a wire brush. Metal carryover from
the brush will compromise the measurement. Cleaning should be followed
by polishing before calibrating the sensor.
The PVC membrane sensors, Ca
++
, K
+
, NH
4
+
, NO
3
-
are fragile
membranes and should be cleaned using a soft artist style paint brush
while rinsing with a stream of water. Dilute dish washing detergents can
be used to remove oily films Solvents or strong acid/alkaline solution
will irreparably harm the electrode.
Calibration may be necessary after cleaning.
POLISHING
Abrasive polishing is only recommended for the solid state crystal
style Combination Electrodes. Teledyne supplies two styles of abrasive
cleaning kits, a package of light blue colored polishing strips or a small vial
of 0.3 micron alumina powder with Q-tips with the fluoride electrodes.
The sensing surface of solid state electrodes can wear over time,
which causes drift, poor reproducibility and loss of response in low level
samples. The electrode can be restored by polishing the sensing surface
with a polishing kit. The polishing kit can also be used if the sensing
surface has been etched or chemically poisoned.