Complexation
Fluoride forms complexes with aluminum, silicon, iron (+3), and
other polyvalent cations as well as hydrogen. The extent of
complexation depends on the concentration of complexing
agent, the total fluoride concentration, and pH of the solution,
and the total ionic strength of the solution.
TISAB II and III contain a reagent, CDTA, that preferentially
complexes aluminum or iron in the sample. In a 1ppm fluoride
sample, TISAB II or III complexes about 5 ppm aluminum or
iron. Higher levels of aluminum or iron can be complexed by
using TISAB IV.
Electrode Life
Electrode should last at least through the warranty period. In
time, the electrode slope will decrease and readings will start to
drift, indicating that electrode should be replaced. Before
replacement, refer to
Troubleshooting Checklist
to verify that
the electrode causes the symptoms.
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Summary of Contents for 96-09
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