​Sodium Metabisulphite (SMBS) is a white/creamy chemical which is soluble in water. Its chemical formula is Na2S2O5, an inorganic compound made up of sodium, sulfur and oxygen, and used in many industries such as food, textile, mining, water treatment, construction chemicals and paper.
Sodium metabisulphite reduces the oxygen tension inducing the typical sickle-shape of red blood cells. Sample: Fresh blood in any anticoagulant. Reagents: 0.2 g of sodium metabisulphite in 10 ml of distilled water.