Hofmeister Phenomena: An Update on Ion Specificity in Biology

Hofmeister's work provided significant information about the importance of ion specificity in biology. Specific ion effects occurred in simple aqueous solutions of electrolytes involving properties such as viscosity, density, refractive index, heat capacity, activity coefficient, freezing point depression and boiling point elevation, and osmotic pressure. Hofmeister's work on the relative effectiveness of different salts on the precipitation of proteins and some other colloids was initiated in the 1870s. He demonstrated that salts and trace amounts of specific ions determined the structure and function of the hierarchically lower structures that supported life. They participated in the osmotic regulation of cells and in the main living processes and any biological system suffered a significant stress when specific salt concentrations were varied or one was replaced with another.