Used as a reagent in analytical chemistry for the determination of quaternary ammonium compounds and certain cations. It forms insoluble precipitates with large organic cations, making it useful in gravimetric and titrimetric methods. Commonly applied in pharmaceutical analysis to assay drugs containing quaternary ammonium groups. Also employed in ion-pair extraction techniques and as a precipitating agent in qualitative inorganic analysis. Its ability to form stable complexes allows for the isolation and identification of specific ions in complex mixtures.