Sodium Meta bisulfite (SMBS) is an inorganic compound known as sodium pyro-sulfite or “disodium meta bisulfite.” SMBS is a sulfur-containing ionic compound, and it is a yellowish-white powder in a normal state. SMBS has a pungent odor like sulfur dioxide. It is a well-known antioxidant that medicine and pharmaceuticals use it. It is also known for its preservative nature because it controls bacteria growth. SMBS is an essential disinfectant and used in many products. Its chemical formula is Na2S2O5.