Monosodium

Monosodium is a general term used in chemistry to describe a salt in which one sodium ion is bound to an acidic residue. It is typically used when an acid with multiple ionizable hydrogens forms a monosodium salt, such as a monosodium phosphate, where one hydrogen of phosphoric acid is replaced by sodium to yield NaH2PO4.

One well-known example is monosodium glutamate (MSG), the sodium salt of the amino acid glutamic acid, widely used as a flavor enhancer in foods. Other common monosodium salts include monosodium phosphate (NaH2PO4), used as a buffering agent and leavening aid in baking and as a water-conditioning chemical; and sodium bisulfate (NaHSO4), the monosodium salt of sulfuric acid, used in cleaning products and as a pH adjuster.

Chemical properties: Monosodium salts tend to be highly water-soluble and can impart acidic or near-neutral pH solutions depending on the remaining acid groups. They often function as buffers because of the remaining acidic protons.

Safety and regulation: MSG has been evaluated by food safety agencies and is generally considered safe at typical dietary intake, though a small subset of people report sensitivity. Other monosodium salts used in food or industry are subject to safety and handling regulations as appropriate for their application.

See also: Sodium salt; Glutamic acid; Food additive.