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6. Before replacing a “faulty” electrode, review the instruction manual
and be sure to:
-Clean the electrode thoroughly
-Prepare the electrode properly
-Use proper filling solutions, CO
2
buffer, and standards
-Measure correctly
-Review
Troubleshooting Checklist
Standard
The quality of results depends greatly upon the quality of the
standards. ALWAYS prepare fresh standards when problems arise,
it could save hours of frustrating troubleshooting! Error may result
from contamination of prepared standards, accuracy of dilution,
quality of distilled water, or a mathematical error in calculating
the concentrations.
The best method for preparation of standards is by serial dilution.
This means that an initial standard is diluted, using volumetric
glassware, to prepare a second standard solution. The second is
similarly diluted to prepare a third standard, and so on, until the
desired range of standards has been prepared.
Sample
If the electrodes work properly in standards but not in samples, look
for possible interferences, complexing agents, or substances which
could affect response or physically damage the sensing electrode or
the reference electrode. If possible, determine the composition of the
samples and check for problems. See
Sample Requirements,
Interferences,
and
pH Requirements.
Technique
Check the method of analysis for compatibility with your sample.
Direct measurement is usually the method of choice for this electrode.
However, known addition may be better for low level work. If the
sample is viscous, analate addition may solve the problem.
Also, be sure that the expected concentration of the ion of interest is
within the electrode’s limits of detection.
If problems persist, review operational procedures and instruction
manuals to be sure that proper technique has been followed. Reread
Measuring Hints
and
Analytical Procedures
.
