The fluoride ion selective electrode is a selective electrode sensitive to the concentration of fluoride ion, the most common one is the lanthanum fluoride electrode.
Lanthanum fluoride electrode is a sensor made of lanthanum fluoride single crystal doped with europium fluoride with lattice holes as the main material. This crystal film has the characteristics of fluoride ion migration in the lattice holes.
Therefore, it has very good ion conductivity. Using this crystal membrane, the fluoride ion electrode can be made by separating two fluoride ion solutions. The fluoride ion sensor has a selectivity coefficient of 1.
And there is almost no choice of other ions in the solution. The only ion with strong interference is OH-, which will react with lanthanum fluoride and affect the determination of fluoride ions. However, it can be adjusted to determine the sample pH <7 to avoid this interference.