Sodium metabisulfite

Chemical properties

Sodium metabisulfite is a white crystalline powder. Sulfur dioxide odor. It may be considered the anhydride of 2 molecules of sodium disulfite.

Chemical properties

Sodium metabisulfite occurs as colorless, prismatic crystals or as a white to creamy-white crystalline powder that has the odor of sulfur dioxide and an acidic, saline taste. Sodium metabisulfite crystallizes from cold water as a hydrate containing seven water molecules.

The Uses of Sodium metabisulfite

sodium metabisulfite is an anti-oxidant and reducing agent.

The Uses of Sodium metabisulfite

Pharmaceutic aid (antioxidant).

The Uses of Sodium metabisulfite

Sodium Metabisulfite is a preservative and antioxidant that exists as crystals or powder having a sulfur dioxide odor. it is readily solu- ble in water. it is used in dried fruits to preserve flavor, color, and to inhibit undesirable microorganism growth. it prevents “black spots” due to oxidative deterioration in shrimp. it is used in maraschino cherries. it is found in lemon drinks as a preservative. see sulfur dioxide.

What are the applications of Application

Sodium metabisulfite is an antioxidant reducing agent, with antimicrobial and antifungal properties

Definition

ChEBI: An inorganic sodium salt composed of sodium and disulfite ions in a 2:1 ratio.

Production Methods

Sodium metabisulfite is prepared by saturating a solution of sodium hydroxide with sulfur dioxide and allowing crystallization to occur; hydrogen is passed through the solution to exclude air. Sodium metabisulfite may also be prepared by saturating a solution of sodium carbonate with sulfur dioxide and allowing crystallization to occur, or by thermally dehydrating sodium bisulfite.

General Description

Sodium metabisulfite (MBS, Sodium disulfite) is an inorganic salt. It is the sodium salt of disulphurous (pyrosulfurous) acid. It is widely used in textile dyeing, photography and paper industry. It is also commonly added to various food products and wines as a preservative.

Hazard

Toxic by inhalation. Upper respiratory tract irritant. Questionable carcinogen.

Health Hazard

Sodium metabisulfite may cause bronchospasm, oculonasal symptoms, and urticaria in sulfite-sensitive individuals; irritation of mucous membranes may occur from inhalation of the dust.

Flammability and Explosibility

Non flammable

Pharmaceutical Applications

Sodium metabisulfite is used as an antioxidant in oral, parenteral, and topical pharmaceutical formulations, at concentrations of 0.01–1.0% w/v, and at a concentration of approximately 27% w/v in intramuscular injection preparations. Primarily, sodium metabisulfite is used in acidic preparations; for alkaline preparations, sodium sulfite is usually preferred. Sodium metabisulfite also has some antimicrobial activity, which is greatest at acid pH, and may be used as a preservative in oral preparations such as syrups.
In the food industry and in wine production, sodium metabisulfite is similarly used as an antioxidant, antimicrobial preservative, and antibrowning agent. However, at concentrations above about 550 ppm it imparts a noticeable flavor to preparations. Sodium metabisulfite usually contains small amounts of sodium sulfite and sodium sulfate.

Contact allergens

This agent is frequently used as a preservative in pharmaceutical products, in the bread-making industry as an antioxidant, and it can induce contact dermatitis. It can be used as a reducing agent in photography and caused dermatitis in a photographic technician, probably acting as an aggravating irritative factor. Sodium metabisulfite contains a certain amount of sodium sulfite and sodium sulfate.

Safety Profile

An inhalation hazard. Poison by intravenous route. Moderately toxic by parenteral route. Experimental reproductive effects. Mutation data reported. When heated to decomposition it emits toxic fumes of SOx and Na2O.

Safety

Sodium metabisulfite is widely used as an antioxidant in oral, topical, and parenteral pharmaceutical formulations; it is also widely used in food products.
Although it is extensively used in a variety of preparations, sodium metabisulfite and other sulfites have been associated with a number of severe to fatal adverse reactions. These are usually hypersensitivity-type reactions and include bronchospasm and anaphylaxis. Allergy to sulfite antioxidants is estimated to occur in 5–10% of asthmatics, although adverse reactions may also occur in nonasthmatics with no history of allergy.
Following oral ingestion, sodium metabisulfite is oxidized to sulfate and is excreted in urine. Ingestion may result in gastric irritation, owing to the liberation of sulfurous acid, while ingestion of large amounts of sodium metabisulfite can cause colic, diarrhea, circulatory disturbances, CNS depression, and death.
In Europe, the acceptable daily intake of sodium metabisulfite and other sulfites used in foodstuffs has been set at up to 3.5 mg/kg body-weight, calculated as sulfur dioxide (SO2). The WHO has similarly also set an acceptable daily intake of sodium metabisulfite, and other sulfites, at up to 7.0 mg/kg body-weight, calculated as sulfur dioxide (SO2).
LD50 (rat, IV): 0.12 g/kg

Potential Exposure

Sodium metabisulfite is used as an antioxidant in pharmaceutical preparations and as a preservative in foods. People with asthma have a greater chance of having an allergic reaction with this chemical. Individuals allergic to sodium bisulfite (a food preservative found in some wine, fresh shrimp; packaged foods; and restaurant salads and potatoes) may have a severe reaction when exposed to sodium metabisulfite.

Carcinogenicity

Sodium metabisulfite was genotoxic in mice in vivo as determined by chromosomal aberration, micronucleus, and sperm shape assays. It was not mutagenic in bacterial assays.

storage

On exposure to air and moisture, sodium metabisulfite is slowly oxidized to sodium sulfate with disintegration of the crystals. Addition of strong acids to the solid liberates sulfur dioxide.
In water, sodium metabisulfite is immediately converted to sodium (Na+) and bisulfite (HSO3-) ions. Aqueous sodium metabisulfite solutions also decompose in air, especially on heating. Solutions that are to be sterilized by autoclaving should be filled into containers in which the air has been replaced with an inert gas, such as nitrogen. The addition of dextrose to aqueous sodium metabisulfite solutions results in a decrease in the stability of the metabisulfite.
The bulk material should be stored in a well-closed container, protected from light, in a cool, dry place.

Shipping

UN1759 Corrosive solids, n.o.s., Hazard class: 8; Labels: 8-Corrosive material, Technical Name required. UN2693 Bisulfites, inorganic, aqueous solutions, n.o.s., Hazard class: 8; Labels: 8-Corrosive material.

Incompatibilities

A strong reducing agent. Keep away from oxidizers. Mixtures with water forms a strong corrosive. Contact with acids releases toxic fumes. Heat causes decomposition. Slowly oxidized to the sulfate on exposure to air and moisture. Attacks metals

Incompatibilities

Sodium metabisulfite reacts with sympathomimetics and other drugs that are ortho- or para-hydroxybenzyl alcohol derivatives to form sulfonic acid derivatives possessing little or no pharmacological activity. The most important drugs subject to this inactivation are epinephrine (adrenaline) and its derivatives. In addition, sodium metabisulfite is incompatible with chloramphenicol owing to a more complex reaction; it also inactivates cisplatin in solution.
It is incompatible with phenylmercuric acetate when autoclaved in eye drop preparations.
Sodium metabisulfite may react with the rubber caps of multidose vials, which should therefore be pretreated with sodium metabisulfite solution.

Regulatory Status

GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (epidural;inhalation; IM and IV injections; ophthalmic solutions; oral preparations; rectal, topical, and vaginal preparations). Included in nonparenteral and parenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.