Thermo Fisher Scientific Ion Selective Electrodes Ammonium - Manual (Page 19)

Instruction Manual Ammonium Electrode
13
TROUBLESHOOTING HINTS
Symptom
Possible Causes Next Step
Out of Range defective meter check meter with Reading
shorting strap
(see meter instruction manual)
electrode(s)
unplug electrode(s)
not plugged in and reset
properly
reference electrode be sure reference
not filled electrode is filled
air bubbles on remove bubble by
membrane redipping electrode
electrodes not put electrode(s)
in solution in solution
"Incorrect
incorrect scaling plot millivolts on the linear
Answer" of semi-log paper axis. On the log axis, be sure
curve is good) concentration numbers within
(but calibration each decade are increasing
with 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:
10-
3
M = 18 ppm NH
4
+ =
14 ppm as N
sample carryover rinse electrodes
thoroughly between samples
Drift (reading
samples and standards allow solutions
slowly changing at different to come to room
in one direction) temperatures temperature
before measurement
electrode exposed soak electrode
to interference in ammonium standard
incorrect reference use recommended
filling solution filling solution