Thermo Fisher Scientific Ion Selective Electrodes Copper - Manual (Page 22)

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1. Be sure to use distilled or deionized water when
following the procedures given in Electrode Slope
Check
.
2.
If the electrode fails to respond as expected, see the
sections Measuring Hints and Electrode Response.
Repeat the slope check.
3.
If the electrode(s) still fail to respond as expected
substitute another cupric ion electrode that is known
to be in good working order for the questionable
electrode. If the problem persists and you are using
an electrode pair, try the same routine with a working
reference electrode.
4.
If the problem persists, the reagent may be of poor
quality, interferences in the sample may be present or
the technique may be faulty. See Reagents, Sample, and
Technique
sections below.
5.
If another electrode is not available for test
purposes, or if the electrode in use is suspect, review
the instruction manual and be sure to:
- Clean and rinse the electrode(s) thoroughly.
- Prepare the electrode(s) properly.
- Use the proper filling solution.
- Adjust the pH and the ionic strength of the solution by
the use of the proper ISA.
- Measure correctly and accurately.
- Review TROUBLESHOOTING HINTS .
Reagents
Whenever problems arise with the measuring procedure that has
been used successfully in the past, be sure to check the reagent
solutions. If in doubt about the credibility of any of the
reagents, prepare them again. Errors may result from
contamination of the ISA, incorrect dilution, poor quality
distilled/deionized water, or a simple mathematical
miscalculation.
Sample
Look for possible interferences, complexing agents, or substances
which could affect the response or physically damage the sensing
electrode (or the reference electrode) if the electrode(s) work
perfectly in the standard, but not in the sample.