International Numbering System (INS) for Food Additives: 513
Food additives Europe numbers: E513
Functional Category
Acidifying agent.
Applications in Pharmaceutical Formulation
Sulfuric acid is used as an acidifying agent in a variety of pharmaceutical and food preparations. It may also be used to prepare dilute sulfuric acid, which, in addition to its use as an excipient, has some therapeutic use for the treatment of gastric hypoacidity, as an astringent in diarrhea, or to stimulate appetite. Sulfuric acid has been used in parenteral, oral, topical, and ophthalmic pharmaceutical formulations
Description
Sulfuric acid occurs as a clear, colorless, odorless, oily liquid. It is very corrosive and has a great affinity for water. The USP32–NF27 specifies that sulfuric acid contains not less than 95% and not more than 98%, by weight, of H2SO4; the remainder is water. See also Section 9
Stability and Storage Conditions
Sulfuric acid is stable but very corrosive and hygroscopic. It will draw moisture from the atmosphere. Sulfuric acid should be stored in a tightly closed container in an explosion-proof area. Containers should be stored out of direct sunlight and away from heat. Avoid heat and moisture. Isolate from incompatible materials. See also Section 12.
Incompatibilities
Avoid storage in close proximity to water, most common metals, organic materials, strong reducing agents, combustible materials, strong bases, carbonates, sulfides, cyanides, strong oxidizing agents, and carbides. Sulfuric acid is a powerful oxidizer and may ignite or explode on contact with many materials. It can react violently with the evolution of a large amount of heat. Oxides of sulfur and hydrogen can be generated during reactions. Great care must be exercised when mixing with other liquids. Always add sulfuric acid to the diluent with great caution.
Safety
Sulfuric acid is widely used in a variety of pharmaceutical formulations. Although concentrated sulfuric acid is very corrosive, it is normally used well diluted in formulations. Concentrated sulfuric acid will react violently with water and much heat is generated. When diluting sulfuric acid, the acid should always be added to the other liquid with great caution. The concentrated solution is extremely corrosive and can cause severe damage or necrosis on contact with the eyes and skin. Ingestion may cause severe injury or death. Inhalation of concentrated vapors can cause serious lung damage. LD50 (rat, oral): 2.14 g/kg(3)