Some inorganic anions such as BF4-, CF3COO-, ClO4-, and H2PO4-, can affect the solubility of proteins and amino acids. Their effects were observed since 1888 by Fran Hofmeister. During the past decade, these ions have been used increasingly in reversed-phase high-performance liquid chromatography (HPLC), because of their abilities to improve the retention of basic substances in their protonated forms without changing a new column or mobile phase pH. Moreover, addition of these ions in mobile phase can improve theoretical plate number and tailing factor as well.
