Ion selective electrode determination of free versus total fluoride ion in simple and fluoroligand coordinated hexafluoropnictate (PnF6-, Pn = P, As, Sb, Bi) salts

Interpretation of the results of determinations of free fluoride (F-f(-)) and total fluoride (F-t(-)) obtained with fluoride ISE while conducting elemental chemical analysis of bulk material of newly synthesized inorganic fluoride compounds is of crucial importance for the purpose of determination of purity and stoichiometry of these compounds. Knowledge of the properties and behavior of these compounds in aqueous media is therefore essential. Observations are presented on the determinations of the amounts of F-t(-) and F-f(-) in fluorinated compounds, in the particular hexafluoropnictate salts (PnF(6)(-), Pn = P, As, Sb, Bi) as found in aqueous media and in some compounds with XeF2, AsF3 ligands. A critical look at the determined amounts of F-f(-), F-t(-) and calculated amounts of bound fluoride (F-b(-)) is provided.