Question

Which eletrode is used for measurment of fluriode ions?

Answer 1

Lanthanum fluoride is a fluoride sensitive electrode which can be used to measure the concentration of the fluoride ions.

Cell notation:

Ag, AgCl | NaF | LaF3 | fluoride anlayte(soln)

NaF,NaCl | AgCl,AgI is an internal reference inside the fluoride selective electrode

And usually a hg, hg+2 is used as external reference electrode.