Application of a fluoride selective electrode to the stoichiometric analysis of lithium carbonate for nuclear purposes

An improved version of a potentiometric method for the determination of lithium has been applied to the accurate, high precision analysis of lithium carbonate, a raw material for the solid-state synthesis of lithium metazirconate (Li2ZrO3). This is one of the most promising tritium breeders in fusion reactors. The analytical procedure consisted of a decomposition of the sample in hydrochloric acid followed by evaporation to dryness. The residual lithium chloride was then dissolved in ethanol and titrated with ammonium fluoride in water-ethanol (1+1). A lanthanum fluoride solid-state ion-selective electrode was used as end point detector. By increasing the analyte concentration and by dissolving the titrant in the mixed solvent, more accurate results where achieved with respect the older procedure. A comparison of the results obtained by this method and those obtained by ion-exchange showed no significant difference (P=0.05). The precision in terms of relative standard deviation was 0.3-0.4%.