Vesifaasiin

Vesifaasiin is the term used in chemistry to describe the aqueous phase in a biphasic liquid–liquid system. It is the water-based phase that is separated from a nonpolar or organic phase, though in some systems it may be the dispersed phase in water-in-oil emulsions. In extraction and formulation work, the distribution of solutes between vesifaasiin and the other phase is governed by polarity, hydrogen bonding, ionic strength, temperature, and pH. The pH can notably alter the partitioning of acids and bases via protonation or deprotonation, changing solubility in each phase.

In practice, vesifaasiin is important for liquid–liquid extraction, pharmaceutical and cosmetic formulations, and food chemistry, where hydrophilic compounds are recovered or purified. Its composition commonly includes water with dissolved salts, buffers, surfactants, and dissolved gases, and its properties such as conductivity, pH, and ionic strength influence solute behavior. The relative polarity and the presence of solutes determine the partition coefficient between vesifaasiin and the coexisting phase.

Analytically, the aqueous phase is characterized by measurements of moisture (water content), pH, conductivity, and composition via chromatography or spectroscopy. The term is often contrasted with the organic phase, sometimes referred to as the oil phase or organic solvent phase. See also aqueous phase, partition coefficient, and liquid–liquid extraction.