Fluoride-ion electrode

Specific ion electrodes, similar in design to the glass electrode, have been developed to analyze for a variety of cations and anions. One of the first to be used extensively was a fluoride ion electrode that is sensitive to F- at concentrations as low as 0.1 part per million and hence is ideal for monitoring fluoridated water supplies. An electrode that is specific for Cl- ions is used to diagnose cystic fibrosis. Attached directly to the skin, it detects the abnormally high concentrations of sodium chloride in sweat that are a characteristic symptom of this disorder. Diagnoses that used to require an hour or more can now be carried out in a few minutes as a result, large numbers of children can be screened rapidly and routinely. 

A single crystal electrode is exemplified by the lanthanum fluoride electrode in which a crystal of lanthanum fluoride is sealed into the bottom of a plastic container to produce a fluoride ion electrode. The container is charged with a... 

Example Fluoride-ion Electrode In this particular instance the membrane essentially comprises of a single crystal of lanthanum fluoride (LaF3), usually doped with a slight trace of europium (II), Eu2+, so as to initiate the crystal defects required for establishing its electrical conductivity. Therefore, the potential developed at each surface of the membrane is finally determined by the exact status of the equilibrium ... 

D.A. Levaggi, W. Oyung, M. Feldstein, Microdetermination of fluoride in vegetation by oxygen bomb combustion and fluoride ion electrode analysis, J. Air Pollut. Control... 

Several species, including [MF6] , [MF7]2-, [MFS]3-, [MF9]4- and [M2Fu] , have been detected in HF solutions of the metals, using a selective fluoride ion electrode,41-43 or by 19F NMR studies.42,44"46 These complexes can be extracted by organic solvents IR showed that solutions of trioctyl amine in To or CC14 extract Mv from 1-12 M HF solutions as [MF6]. 47... 

Pentahalides form adducts with nearly all types of neutral or anionic donors. " The high Lewis acidity of MF5 is illustrated by facile fluoride transfer and formation of anionic adducts. Species such as MF ", n = 1-4) and M2Fn have been detected in HF solutions of the metals using a selective fluoride ion electrode or by F NMR. These complexes... 

Fluoride ion electrode method, internal standard, dilutions at 0.1, 0.02, 0.01. Colorimetric method with internal standard, dilution at 0.004. 

For an idea of some historic and more recent applications of electrochemical techniques, the reader is referred to Table 2.11 of applications providing examples of applications of electrochemical analytical techniques to elemental determinations in a variety of materials. Shearer and Morris (1970) report on the microdetermination of fluorine in organic compounds with a fluoride ion electrode following an oxygen flask combustion based on the careful work of Morris. Dabeka et al. (1979) developed a microdiffusion and fluoride-specific electrode determination of fluoride in foods. Determination of lead and cadmium in foods by anodic stripping voltammetry ... 

Shearer DA and Morris GF (1970) Microdetermination of fluorine in organic compounds with a fluoride ion electrode following an oxygen flush combustion. Microchem J 15 199—204. 

The fluoride ISE is used routinely for measuring fluoridated water and fluoride ion in dental products such as mouthwash. A 50 mL aliquot of water containing sodium fluoride is analyzed using a fluoride ion electrode and the method of standard additions. The pH and ionic strength are adjusted so that all fluoride ion is present as free F ion. The potential of the ISE/reference electrode combination in a 50 mL aliquot of the water was —0.1805 V. Addition of 0.5 mL of a 100 mg/L F ion standard solution to the beaker changed the potential to —0.3490 V. Calculate the concentration of (1) fluoride ion and (2) sodium fluoride in the water sample. 

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