Sodium tetraphenylboron is widely used in analytical chemistry as a reagent for the quantitative determination of potassium, ammonium, and other cations. It forms insoluble salts with these ions, allowing for their precipitation and subsequent measurement. In organic synthesis, it serves as a phase-transfer catalyst, facilitating reactions between compounds in different phases. Additionally, it is employed in the preparation of organoboron compounds and as a stabilizing agent in certain polymerization processes. Its ability to form stable complexes with specific ions also makes it useful in ion-selective electrodes and in the purification of pharmaceuticals.