Thermo Fisher Scientific Ion Selective Electrodes Calcium - Manual (Page 17)

Instruction Manual Calcium Electrode
17
TROUBLESHOOTING HINTS
Symptom
Possible Causes Next Step
Out of Range defective meter check meter with shorting strap
Reading (see meter instruction manual)
defective electrode check electrode operation
electrodes not unplug electrodes and reset
plugged in properly
reference electrode be sure reference electrode is filled
not filled
air bubbles on remove bubbles by
membrane re-dipping electrode
electrodes not put electrodes in solution
in solution
Noisy or Unstable
defective meter check meter with
Readings (readings shorting strap
continuously or
randomly changing air bubble on
remove bubble by
membrane re-dipping electrode
meter or stirrer ground meter or stirrer
not grounded
outer filling solution fill electrode to level just
too low below fill hole
defective electrode replace electrode
electrode exposed to soak electrode in calcium standard
interferences
"Incorrect
incorrect scaling plot millivolts on the linear
Answer" of semi-log paper axis. On the log axis, be sure
(but calibration concentration numbers within
curve is good) each decade are increasing
increasing concentration
incorrect sign be sure to note sign of
millivolt number correctly
incorrect standards prepare fresh standards
wrong units used apply correct conversion factor:
1.0x10
-3
M = 40 ppm Ca
+2
=
100 ppm as CaCO
3
sample carryover rinse electrodes thoroughly