Thermo Fisher Scientific Ion Selective Electrodes Potassium - Manual (Page 15)

Instruction Manual Potassium Electrode
15
Technique
Be sure that the electrode's limit of detection has not been exceeded. Be sure that the analysis
method is clearly understood and that Good Laboratory Practice has been followed.
Refer to the instruction manual again. Reread sections
GENERAL PREPARATION
and
ELECTRODE
CHARACTERISTICS.
If trouble still persists, call Eutech Instruments Pte Ltd. at (65) 6778-6876 and ask for the Customer
Services Department.
TROUBLESHOOTING HINTS
Symptom
Possible Causes Next Step
Out of Range defective meter check meter with shorting strap
Reading (see meter instruction manual)
electrode(s) not unplug electrode(s) and reset
plugged in properly
reference
electrode be sure reference electrode is
not filled filled
air bubbles on remove bubble by
membrane redipping electrode
electrodes
not put electrode(s) in solution
in solution
"Incorrect Answer"
incorrect scaling plot millivolts on the linear axis.
(but calibration of semi-log paper On the log axis, be sure
curve is good) concentration numbers within
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 = 39 ppm K
+1
= 75 ppm as KCl
sample
carryover rinse electrodes thoroughly
between samples