The antimony electrode has been investigated for its ability to function as a
pH electrode.
[Bates, Roger G. ''Determination of pH: theory and practice''. Wiley, 1973, pp 252-256] The electrode is made of elemental
antimony
Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient time ...
. The electrochemical process can be formulated as
:Sb
2O
3(s) + 6 H
+ + 6 e
− 2Sb(s) + 3H
2O
The oxide, Sb
2O
3, is present on the surface of the electrode. Although this electrode does not give measurements of high accuracy, its rapid response, simplicity and rugged construction make it useful for continuous industrial pH monitoring. It can be used at elevated temperatures.
In an unusual application, an antimony electrode was used to measure pH inside the human stomach. The simplicity of construction meant that the electrode could be made small enough to be swallowed. Thin copper wires were attached to the electrode and one terminal on a pH meter. The subject's foot was placed in a saline solution. A calomel reference electrode was also placed in this solution and was connected to the other terminal on the meter.
Antimony electrodes continue to be used for ''in vivo'' measurements. The use of antimony-based electrodes for analytical determinations has been reviewed.
Antimony electrodes are available commercially. They can be employed with solutions containing
hydrofluoric acid
Hydrofluoric acid is a Solution (chemistry), solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly Corrosive substance, corrosive. It is used to make most fluorine-containing compounds; examples include th ...
for which the
glass electrode
A glass electrode is a type of ion-selective electrode made of a doped glass membrane that is sensitive to a specific ion. The most common application of ion-selective glass electrodes is for the measurement of pH. The pH electrode is an example ...
cannot be used because of the reaction of glass with solutions containing
hydrogen fluoride
Hydrogen fluoride (fluorane) is an inorganic compound with the chemical formula . This colorless gas or liquid is the principal industrial source of fluorine, often as an aqueous solution called hydrofluoric acid. It is an important feedstock i ...
.
References
Electrodes
Electroanalytical chemistry devices
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