CAS : 7681-57-4 Assay : 97-98% SO2% : 64-65% Sodium metabisulphite  is an inorganic compound composed of sodium, sulfur dioxide. Its chemical formula is Na2S2O5. SMBS typically comes in a white, or yellowish-white crystalline powder, which is easily soluble in water, and leaves that familiar sulfur (rotten egg) smell.it is widely used as food preservative in food industry. Sodium meta bisulfite food grade also known as Sodium meta bisulfite, SMBS, Sodium meta bisulfate, sodium hydrogen sulphite. It is widely used as Food Preservatives, Pharmaceutical Industry, Laboratory Chemicals, Leather Treatment, Photograph, Specialty Chemicals, Dye & Intermediates, Effluent Treatment, Metal Cleaning Chemical, Textile Industry, Oil Field Chemicals, Paper Mills, Agro Industry etc