SODIUM METABISULFITE

Sodium metabisulfite = SMBS

CAS Number: 7681-57-4
EC Number: 231-673-0
E number: E223 (preservatives)
Linear Formula: Na2S2O5
Molecular Weight: 190.11

Sodium metabisulfite or sodium pyrosulfite is an inorganic compound of chemical formula Na2S2O5. 
Sodium metabisulfite is sometimes referred to as disodium metabisulfite. 
Sodium metabisulfite is used as a disinfectant, antioxidant, and preservative agent.
Sodium Metabisulfite is generally immediately available in most volumes. 
Sodium metabisulfite has a high purity, submicron and nanopowder forms may be considered. 

Sodium Metabisulfite (sodium bisulfite anhydrous, sodium pyrosulfate, SMBS, MBS) is a white inorganic crystalline compound with the chemical formula Na2S2O5.
Sodium metabisulfite is an inorganic compound used as an antioxidant, a preservative in food, or for dichlorination in a broad range of industrial applications.

Sodium metabisulfite uses
Sodium metabisulfite have many major and niche uses. 
Sodium metabisulfite is widely used for preserving food and beverages.
Sodium metabisulfite is added as an excipient to medications which contain adrenaline (epinephrine), in order to prevent the oxidation of adrenaline.
For example, Sodium metabisulfite is added to combination drug formulations which contain a local anaesthetic and adrenaline, and to the formulation in epinephrine autoinjectors, such as the EpiPen.
This lengthens the shelf life of the formulation, although the sodium metabisulphite reacts with adrenaline, causing Sodium metabisulfite to degrade and form epinephrine sulphonate.
In combination with sodium hydrosulfite Sodium metabisulfite is used as a rust-stain remover
Sodium metabisulfite is used in photography.
Concentrated sodium metabisulfite can be used to remove tree stumps. 
Some brands contain 98% sodium metabisulfite, and cause degradation of lignin in the stumps, facilitating removal.
Sodium metabisulfite is also used as an excipient in some tablets, such as paracetamol.

A very important health related aspect of this substance is that Sodium metabisulfite can be added to a blood smear in a test for sickle cell anaemia (and other similar forms of haemoglobin mutation). 
The substances causes defunct cells to sickle (through a complex polymerisation) hence confirming disease.
Sodium metabisulfite is used as a bleaching agent in the production of coconut cream
Sodium metabisulfite is used as a reducing agent to break sulfide bonds in shrunken items of clothing made of natural fibres, thus allowing the garment to go back to its original shape after washing
Sodium metabisulfite is used as a SO2 source (mixed with air or oxygen) for the destruction of cyanide in commercial gold cyanidation processes.
Sodium metabisulfite is used as a SO2 source (mixed with air or oxygen) for the precipitation of elemental gold in chloroauric solutions.
Sodium metabisulfite is used in the water treatment industry to quench chlorine residual
Sodium metabisulfite is used in tint etching iron-based metal samples for microstructural analysis.
Sodium metabisulfite is used as a fungicide for anti-microbe and mould prevention during shipping of consumer goods such as shoes and clothing. 

Sodium metabisulfite (also known as sodium bisulfite) is an affordable and effective selective precipitant for gold. 
Sodium metabisulfite can recover up to 99.95% of pure gold when the precipitated gold is thoroughly rinsed. 
Sodium metabisulfite works well even at room temperature. 
This product has a chemical grade purity of 99.98%.
Proper ventilation is required. 
Sodium metabisulfite has a very strong, pungent, acid odor and is corrosive.
Precipitated gold particles vary in size, but tend to be small and float easily in the rinse water. 
For this reason, special care must be taken to avoid accidentally pouring off gold with the rinse water.

Plastic stickers and packaging containing the anhydrous, sodium metabisulfite solid active ingredient are added prior to shipping. 
The devices absorb moisture from the atmosphere during shipping and release low levels of sulfur dioxide.
Sodium metabisulfite is used for preserving fruit during shipping.
Sodium metabisulfite is used as a solvent in the extraction of starch from tubers, fruit, and cereal crops.
Sodium metabisulfite is used as a pickling agent to treat high pressure reverse osmosis water desalination membranes for extended storage periods between uses.

Sodium metabisulphite is used as an antioxidant agent in many pharmaceutical formulations. 
Sodium metabisulfite is extensively used as a food preservative and disinfectant. 
Sodium metabisulfite has been demonstrated that sulphite exposure can affect some organs. 
Curcumin, the main element of Curcuma longa, has been identified to have multiple protective properties. 

Sodium metabisulfite applications
-Cyanide destruction and leaching in the mining industry (Manganese, Gold, Cobalt, Iodine, Nickel and Silver)
-Dechlorination in municipal wastewater, pulp & paper, power, and textile water treatment plants
-Disinfectant
-Water treatment in leather tanning process
-Oxygen scavenger
-Cherry brining process
-Preservative in photo developer solutions
-Antioxidant
-Used in production of cleaning agents, detergents, and soaps

Sodium metabisulfite is used as a food additive, mainly as a preservative and is sometimes identified as E223. 
As an additive, Sodium metabisulfite may cause allergic reactions, particularly skin irritation e.g. eczema; gastric irritation and asthma. 
Sodium metabisulfite is not recommended for consumption by children. 
Sodium metabisulfite is present in many dilutable squashes. 
Sodium metabisulfite is commonly used in home brewing preparations to sanitize equipment. 
Sodium metabisulfite is used as a cleaning agent for potable water reverse osmosis membranes in desalination systems. 
Sodium metabisulfite is also used to remove chloramine from drinking water after treatment.

Sodium metabisulphite (SMBS), the commercially produced salt of sulphurous acid, is a preservative used to extend the shelf life of meat products such as fresh sausages and burgers, even though it can have adverse effects on some people, especially asthmatics. 
SMBS is not permitted in several countries for use in meat products. 
Chemically, SMBS contains 67% sulphur dioxide (SO2). 
When SMBS is applied to a meat product, the SMBS instantly reacts with water and, as a rule of thumb, around 50–55% added SMBS can be found analytically in the meat product as SO2. 
Some SO2 is ‘lost’ as a result of countless reactions and cannot be detected any longer. 
Therefore meat products are not analysed with regard to their SMBS content. 
The level of SO2 has to be measured instead and food standards refer to the SO2 level, rather than the SMBS level, of a product. 
In countries such as Australia and New Zealand, 500 ppm of SO2 is the maximum per kilogram of fresh sausage. 
In the UK, SMBS is permitted in certain meat products only and Sodium metabisulfite is not permitted in most other countries within the EU. 
One of the reasons that Sodium metabisulfite is not permitted in some countries is that SMBS causes a significant loss in vitamins such as thiamin in foods.

Sodium metabisulfite preparation
Sodium disulfite can be prepared by treating a solution of sodium hydroxide with sulfur dioxide.
When conducted in warm water, Na2SO3 initially precipitates as a yellow solid. 
With more SO2, the solid dissolves to give the disulfite, which crystallises upon cooling.
SO2 + 2 NaOH → Na2SO3 + H2O
SO2 + Na2SO3 → Na2S2O5
which yields a residue of colourless solid Na2S2O5.

What is Sodium Metabisulfite?
Sodium metabisulfite is a reducing agent used in  dough. 
Sodium metabisulfite is used frequently in cookie and cracker production. 
Sodium metabisulfite is also used as a preservative for baked goods, wine, dried fruit and jams due to its antioxidant capacity.

Sodium metabisulfites chemical structure
The anion metabisulfite consists of an SO2 group linked to an SO3 group, with the negative charge more localised on the SO3 end. 
The S–S bond length is 2.22 Å, and the "thionate" and "thionite" S–O distances are 1.46 and 1.50 Å, respectively.

CAS Number: 7681-57-4 
CHEBI:114786 
ChEMBL: ChEMBL2016976 
ECHA InfoCard: 100.028.794 
EC Number: 231-673-0
E number: E223 (preservatives)
PubChem CID: 656671
RTECS number :UX8225000
UNII: 4VON5FNS3C
CompTox Dashboard (EPA): DTXSID0029684

Sodium metabisulfite is commonly used as preservative in foods but can oxidize to sulfite radicals initiating molecular oxidation. 
Ghrelin is a peptide hormone primarily produced in the stomach and has anti-inflammatory effects in many organs. 
Sodium Metabisulfite is a common additive used to preserve and stabilize wines, ciders, and occasionally beers. 
When added to wine or must, Sodium metabisulfite forms sulfur dioxide gas (SO2). 
This prevents most wild microorganisms from growing and acts as a potent antioxidant, protecting both the color and delicate flavors of wine. 
Sodium metabisulfite solutions are also used as sanitizing rinses for winemaking equipment.
Sodium metabisulfite functions identically to potassium metabisulfite. 
Potassium metabisulfite is usually preferred as an additive becuase Sodium metabisulfite does not contribute any dietary sodium, but sodium metabisulfite is more popular as a sanitizing rinse.

Recommended Usage
Dosage varies when used to kill wild bacteria in must, halt fermentation, or preserve finished wines against oxidation. 
The addition of ¼ teaspoon of sodium metabisulfite to 5 gallons contributes approximately 50 ppm of free SO2.
To make a sanitizing rinse for equipment, dissolve 8 teaspoons of sodium metabisulfite into 1 gallon of water. 
High concentrations of sulfur dioxide gas are irritating and toxic, so use in a well ventilated area. 
After applying the solution to your equipment, the items must be rinsed with clean, cold water.

Chemical formula: Na2S2O5, Na-O-(S=O)-O-(S=O)-O-Na
Molar mass: 190.107 g/mol
Appearance: White to yellow powder
Odor: Faint SO2
Density: 1.48 g/cm3
Melting point: 170 °C (338 °F; 443 K) decomposition begins at 150 °C
Solubility in water:
45.1 g/100 mL (0 °C)
65.3 g/100 mL (20 °C)
81.7 g 100 mL (100 °C)
Solubility:
Very soluble in glycerol
Slightly soluble in ethanol

What Is Sodium metabisulfite?
Sodium Sulfite, Potassium Sulfite, Ammonium Sulfite, Sodium Bisulfite, Ammonium Bisulfite, Sodium Metabisulfite and Potassium Metabisulfite are inorganic sulfite salts. 
In cosmetics and personal care products, these ingredients are used in the formulation of permanent waves, hair bleaches, hair dyes, colors and tints, and in some bath and skin care products.

Why is Sodium metabisulfite used in cosmetics and personal care products?
All these ingredients function as reducing agents, which means they donate hydrogen molecules to other substances in cosmetics and personal care products. 
With the exception of Sodium Metabisulfite, these ingredients also modify hair fibers to facilitate changes to the structure of the fibers, such as with permanent waves or with hair straightening. 
In addition, Sodium Sulfite, Potassium Sulfite, Sodium Bisulfite and Sodium Metabisulfite function as antioxidants preventing or slowing deterioration of cosmetics and personal care products caused by chemical reactions with oxygen.

Scientific Facts about Sodium metabisulfite: 
Sodium Sulfite, Sodium Bisulfite, Potassium Bisulfite, Sodium Metabisulfite and Potassium Metabisulfite are referred to as sulfiting agents because they release sulfur dioxide under certain conditions.

What Are The Benefits of Sodium Metabisulfite?
In cosmetics and personal care products, sodium metabisulfite functions as an antioxidant preservative and a hair-waving/straightening agent.

Preservative
As an antioxidant preservative, sodium metabisulfite works by protecting the other ingredients in a formulation from oxidation. 
Oxidation occurs when products are exposed to air. 
Oxidation changes the composition of some of the formulation’s ingredients such as fats and oils. 
Oxidation results in rancidity, color changes, viscosity changes, and deterioration of active ingredients in your skincare and bodycare products. 
Adding an antioxidant preservative like sodium metabisulfite will make the product less susceptible to degradation when exposed to environmental elements and prevent the growth of bacteria and molds.

Sodium metabisulfite and hair care
In addition to use as an antioxidant preservative, sodium metabisulfite functions as a hair-waving/straightening agent. 
Sodium metabisulfite is often used in combination with sodium sulfite and sodium sulfate in products used to straighten the hair and in permanent waves. 
Other hair care products that use sodium sulfite include hair bleaches, hair dyes, colors and tints.

Synonyms:
Sodium disulfite
Sodium pyrosulfite
Sodium metabisulfite

How is Sodium Metabisulfite made?
Sodium metabisulfite can be made from the reaction between sulfur dioxide with sodium carbonate. 
The following is the reaction equation: SO2 + Na2SO3 → Na2S2O5
Here is the manufacturing process came up by Solvay (1): Reaction between sodium carbonate (Na2CO3) and sodium bisulfite (NaHSO3) solution to form the mixed solution of sodium bisulfite and sodium sulfite (Na2SO3). 
Reaction equation: Na2CO3+2NaHSO3 = Na2SO3+H2O+CO2
Add excess sulfur dioxide (SO2) to the above solution to convert sodium sulfite to sodium bisulfite and also obtain the dissolved sulfur dioxide. 
Reaction equation: Na2SO3+H2O+SO2=2NaHSO3
Convert the dissolved sulfur dioxide to sodium bisulfite by adding an alkali ingredient, e,g, sodium carbonate, sodium hydroxide, or sodium sulfite, or the mixtures. 
Reaction equation: Na2CO3+H2O+SO2=2NaHSO3+CO2
Obtaining sodium metabisulfite (Na2S2O5) through two sodium bisulfite molecules reacts itself by cooling the above sodium bisulfite solution, and follows purification and drying processes to produce crystals or powder. 
Reaction equation: 2NaHSO3 = Na2S2O5+H2O

What is Sodium metabisulfite?
Sodium metabisulfite has a molecular formula of Na2O5S2 and is consider an antioxidant. 
Sodium metabisulfite is used as a food preservative and in the commercial wine making industry. 
In the paper and textile industry Sodium metabisulfite is used as a bleaching agent. 
Sodium metabisulfite can be associated with serious allergic reactions. 
Although primary exposure in children is through foods, serious reactions have also occurred after oral, inhalational, parenteral, and ophthalmic administration of sulfite-containing drugs. 
Reactions to sulfites most often occur in patients with reactive airway disease like asthma. 
Symptoms most frequently reported include wheezing, dyspnea, and chest tightness; anaplylaxis has also been reported. 
Sulfites have been removed from metered-dose inhalers, including albuterol. 
The diagnosis of a sulfite sensitivity is made by history and through a challenge testing with a qualified physician. 
Read food package labels carefully to avoid sulfites in foods. 
In addition, drug manufacturers are required to list the inclusion of sulfites in medicine product labeling. 
Metabisulfites may be present in some intravenous preparations. 
People who do not have a sensitivity to sulfites rarely show any reaction.

Application of sodium metabisulfite in food industry
Sodium Metabisulfite is widely used in food industry. 
Besides bleaching effect, Sodium Metabisulfite also owns the following functions:
1) Sodium Metabisulfite in food has anti-browning effects. 
Enzymatic browning often occurs in fruit, potato food. 
Sodium Metabisulfite is a kind of reducing agent, has a strong inhibitory effect on the polyphenol oxidase activity. 
0.0001% of sulfur dioxide can reduce 20% of the enzyme activity, 0.001% of sulfur dioxide can completely inhibit the enzyme activity and can prevent enzymatic browning; In addition, can consume oxygen in food organization and has deoxidation effect. 
Furthermore, sulfite and glucose can have addition action, prevent glucose and amino acids in food ammonia reaction sugar ammonia reaction, so as to own the function of anti-browning.
2) Sodium Metabisulfite in food has antiseptic effect. 
Sodium Metabisulfite can play the role of acidic preservative, the undissociated sulfurous acid is considered Sodium metabisulfite can inhibit yeasts, moulds and bacteria. 
The inhibition of undissociated sulfurous acid for colon bacillus is 1000 times stronger than Hydrogen sulfite, 100 to 500 times stronger than beer yeast, 100 times stronger than leaf mold. 
Sulfur dioxide in the acid has the most powerful anti microorganism effects.
3) Sodium Metabisulfite in food has loosen machine effect. 
Sodium Metabisulfite can be used as the constituent of loosen machine.
4) Sodium Metabisulfite in food has oxidation resistance effect. 
Sodium Metabisulfite has distinctive resistance effect. 
Sulfurous acid is strong reducing agent, Sodium metabisulfite can consume the oxygen in organization of fruits and vegetables, inhibit the activity of inhibit the activity of oxidizing enzyme, it is effective to prevent oxidation and breaking of vitamin C in fruits and vegetables.

The mechanism Sodium Metabisulfite effects: Decolorizers can be divided into two types by its function: oxidation type bleaching agent & reducing type bleaching agent. Sodium Metabisulfite belongs to reducing type bleaching agent.

What’re the Uses of Sodium Metabisulfite?
Sodium metabisulfite is a strong reducing agent that can react with oxidizing agents as the sulfur atom in Sodium metabisulfite with a positive valence of 4, the maximum valence of which is 6. 
That is the mechanism why sodium metabisulfite is a multifunctional ingredient that can be used as a preservative, antioxidant and bleaching agent in agricultural food products, wine and other applications.

Preservative
SMBS is a sulfur-containing preservative that inhibits the oxidase in the food, and also can block the normal physiological oxidation process of microorganisms and thus inhibit the reproduction of microorganisms in food preservation. 

Antioxidant
Since sulfite is a strong reducing agent, Sodium metabisulfite reacts with oxygen from fruits and vegetables and also inhibits oxidase activity, so it prevents food spoilage caused by oxidation and protects vitamin C in them.

Bleaching agent
Reduce the colored material to a bright and fresh color or prevent/slow oxidative browning.

Wine
You may have seen sulfur dioxide in the ingredients list of wine, but not like other ingredients you notice in the label, sulfur dioxide is not directly added to wine, it is formed by the adding of sodium metabisulfite or potassium metabisulfite. 
The following are the reaction equation of Na2S2O5 in wine:

Na2S2O5 + H2O <===> 2Na+ + 2(HSO3)-
HSO3- + H+ <===> H2O + SO2 
Sulfur dioxide plays an important role in almost every manufacturing process of winemaking, from grape picking to bottling. 
Sodium metabisulfite is mainly to inhibit the growth of yeast and bacteria, and therefore preserve the wine fresh and extend the shelf life. 

Sodium metabisulfite or potassium metabisulfite is commonly added to wines, ciders, or maybe beers as an antioxidant, preservative and stabilizer. 
Also, Sodium metabisulfite can be used to clean and sanitize wine equipment and wine bottles. 

Sodium metabisulfite is commonly used to precipitate dissolved gold out of aqua regia and gold chloride solutions. 
When Sodium metabisulfite is dissolved into water, Sulfur dioxide gas is created which is excellent at precipitating gold from the solution.
Sodium metabisulfate is a popular choice in this process because Sodium metabisulfite is more selective in precipitating gold by itself.

Sodium metabisulfite (SMBS) is not a disinfectant. SMBS dissolved in water converts to sodium bisulfite.  
When dosed online at high dosages, Sodium metabisulfite is an oxygen scavenger and many biofilm forming bacteria are anaerobic, making oxygen scavenging useless.  
In many cases, such high dosages have been associated with increased biological growth, especially where the water contains high TOC levels.
SMBS does however prevent fungal growth in membranes when used as a storage solution, because most fungi can’t grow without oxygen.  
Sodium metabisulfite goes without saying that growth of aerobic bacteria is also inhibited under these storage conditions.
Fungus requires nitrogen for growth making polyamide membranes especially susceptible to deterioration should fungal growth not be prevented.  
Fungi and heterotrophic bacteria obtain their energy from organic compounds, so Sodium metabisulfite’s important to clean the membranes well and remove all organic foulants from the membrane surface prior to long term storage in bisulfite solution.

Bakery 
Like L-cysteine, sodium metabisulfite functions as a reducing agent in biscuit/pastry dough which loosens the dough, reduces the rest time and accelerates the kneading process by reacting with disulfide bonds and generating thiolsulfate esters in gluten protein after hydrolyzed to bisulfite (HSO3−) in water.

Processed fruit products
Like other sulfites (e.g. sodium sulfite, sulfur dioxide), sodium metabisulfite can be used as both a preservative and antioxidant in processed fruit products to slow browning reactions, as well as inhibit the growth of certain microorganisms. 

Industrial 
Industrial grade sodium metabisulfite is used in a wide range of applications: 

Pharmaceuticals: used for the purification of chloroform, phenyl propyl sulfone and benzaldehyde.
Rubber: a coagulant.
Printing and dyeing:  as a dechlorination agent for bleached cotton.
Leather: impart leather the properties of soft, waterproof, folding resistance in leather treatment.
Surfactants and polymerization: as a sulfonating agent and reducing agent.
Gold refining: as a reducing agent to precipitate gold out of an aqua regia solution by reducing the Au³⁺ to Au.

What Is Sodium Metabisulfite?
Sodium metabisulfite is an antioxidant-based preservative that is used in cosmetics and skincare products to prevent contamination by bacteria and mold and to extend the shelf-life of products. 
Antioxidants help to prevent oxidation of products which is a natural process that occurs when oxygen takes electrons from the ingredients in the formulation, changing their composition and efficacy. 
Oxidation often is associated with a change in the color and texture of a product. 
Antioxidants donate electrons to oxygen so that Sodium metabisulfite doesn’t damage the formulation. 
Additionally, sodium metabisulfite prevents the growth of bacteria and yeasts in a similar way, making it an effective preservative. 
Preservatives are important for the stability of your product and help to reduce contamination through use and from general environmental contamination from being open. 
Sodium metabisulfite, also known as sodium pyrosulfite, is a white crystalline or powder solid with a slight sulfur odor. 
In addition to use in the cosmetic industry, sodium metabisulfite functions as a food preservative with the code E223. 
Sodium metabisulfite is commonly used to stabilize wine or beer. 
When added to these beverages, the sulfite compounds release sulfur dioxide gas, which prevents oxidation and also inhibits the growth of yeasts and fungi. 
Additionally, sodium metabisulfite is used in the medical industry, in the oil and gas industry, and various other industries for different purposes. 
Sodium metabisulfite also functions as a hair-waving/straightening agent.

Is Sodium Metabisulfite Safe to Eat?
Yes, Sodium metabisulfite almost has no side effects and the safety has been approved by the U.S. Food and Drug Administration (FDA) and European Food Safety Authority (EFSA), as well as the Joint FAO/WHO Expert Committee on Food Additives (JECFA).  

In food industry as additive (E223) preservative, antioxidant and antimicrobic for fruits (dried, glazed and
candled), vegetables (onions, potatoes, etc.), juices (citrus and grapes) and fish (shrimps and prawns).
In silage treatment as antifermentative.
In starch and sweeteners production as bacteriostatic.
In the photographic industry as component of developer bath.
In desalting plants with reverse osmosis (for removing the excess of chlorine and for membrane preservation) or in drinking water treatment (to remove the excess of chlorine).
In chemical synthesis in the production of acrylic fibres, vitamin K and A, pharmaceutical intermediates, etc

CAS Number: 7681-57-4
Formula Weight: 190.10
Formula: Na2S2O5
Density (g/mL): 1.33
Boiling Point (°C): 104
Solubility: Water and Alcohol
Synonyms: Sodium Pyrosulfite Anhydrous
Shelf Life (months): 12
Storage: Green

Sodium Metabisulfite, (often referred to as SO2, sulfites meta, or meta-bi) has several uses in winemaking. 
Sodium metabisulfite is used at the crush, to help control the spoilage bacteria and indigenous yeast that may already be present on the fruit or the equipment. 
The amount used is enough to stop most of the unwanted organisms but not enough to hinder a cultured yeast, which has a higher tolerance to sulfites. 
This effectively “wipes the slate clean” for the cultured yeast to step in and rapidly colonize the must.
Sulfites also help to inhibit the enzymatic browning of musts and finished wines. 
During storage and in the bottle, sulfites at the proper levels will protect a wine by continuing to inhibit spoilage organisms, as well as by scavenging oxygen.
Campden tablets are Sodium Metabisulfite in an easier to measure format. 
Adds 75 ppm of sulfites at the rate of one tablet per gallon. 
These must be fully ground-up prior to use. 
Potassium Meta-bi in powder form, AD495 or AD500, is much easier to use if you have a scale and does not add sodium to your wine.
Sodium metabisulfite is possible the sodium could contribute a very small salty flavor. 
Especially when making white wine Sodium metabisulfite is preferable to add potassium over sodium since added potassium can later help with cold stabilization.

FDA
Sodium metabisulfite is generally recognized as safe (GRAS) when used as a preservative except in meats, foods recognized as a source of vitamin B1 and fresh fruits or vegetables.

EFSA
Sodium metabisulfite (E223) is listed in Commission Regulation (EU) No 231/2012 as an authorised food additive and categorized in “ additives other than colours and sweeteners”

Sodium metabisulfite is a chemical compound with the formula Na2S2O5. 
Sodium metabisulfite is also known as sodium pyrosulfite and sodium disulfite. Na2S2O5 is an ionic compound containing the sodium cation (Na+) and the metabisulfite anion (S2O52-). 
In its standard state, sodium metabisulfite exists as a white or yellowish-white powder, as shown below.

THE GOOD: Helps to preserve your product, reducing contamination and extending its shelf life.
THE NOT SO GOOD: Has been linked to allergy and sensitivity in some skin types.
WHO IS IT FOR? All skin types except those that have an identified allergy to it.
SYNERGETIC INGREDIENTS: Works well with most ingredients
KEEP AN EYE ON: Its other name, E223, which is what sodium metabisulfite is called when used as a food additive.

What is Sodium Metabisulfite used for?
In cosmetics and personal care products, sodium metabisulfite functions as an antioxidant preservative and a hair-waving/straightening agent. 
As an antioxidant preservative, sodium metabisulfite works by protecting the other ingredients in a formulation from oxidation, which is the loss of electrons.

Other names
Sodium pyrosulite
Sodium disulfite
Sodium metabisulfite
7681-57-4
Sodium pyrosulfite
Sodium disulfite
Disodium disulphite

Sodium Metabisulfite, Anhydrous, Granular, Reagent, ACS, also known as disodium or metabisulfite, is typically used as an antioxidant, disinfectant or preservative agent. 
As an ACS grade quality reagent, Sodium metabisulfites chemical specifications are the de facto standards for chemicals used in many high-purity applications and typically designate the highest quality chemical available for laboratory use. 
Spectrum Chemical manufactured Reagent ACS grade products meet the toughest regulatory standards for quality and purity.

Sodium metabisulfite (MBS) is used as a preservative in food and wine and frequently triggers attacks of asthma. 
To determine the characteristics of responses to inhaled MBS, 30 asthmatic subjects and 16 nonasthmatic subjects inhaled MBS, in concentrations of 6.2, 12.5, 50, and 100 mg/ml, from a DeVilbiss No. 40 nebulizer in doses ranging from 0.1 to 12.8 µmol. 
Response was measured as the dose that caused a 20% fall in FEV1 (PD20FEV1). 
All the asthmatic subjects responded; one of the atopic, nonasthmatic subjects responded and none of the nonatopic, nonasthmatic subjects responded. 
The response occurred within 1 min, and most subjects recovered to within 10% of baseline after 30 to 40 min. 
Dose-response curves to MBS were steep and were reproducible, within a 7-day period, to within one doubling dose, with mean PD20FEV1 values of 2.17 and 2.11 µmol in 11 subjects. 
There was no correlation between PD20FEV1 values to MBS and histamine, and inhalation of MBS did not enhance responses to subsequent challenge with histamine (mean PD20FEV1 to histamine was 0.65 µmol and to histamine 1 h after MBS was 0.74 µmol). 
Challenge with MBS (mean PD20FEV1 4.07 µmol) did not cause refractoriness to a second challenge 1 h later (mean PD20FEV1 5.39 µmol). 
Of 20 subjects tested, prior inhalation of 8 mg nedocromil sodium blocked the response to MBS in 15 subjects and reduced it in two others. 
Cromolyn sodium (4 mg) blocked the response to MBS in three subjects but did not alter the mean PD20FEV1 in the remaining 17 subjects. 
The characteristics of responses to MBS suggest that the response is due to the effect of inhaled SO2. 
Sodium metabisulfites mode of action, like that of SO2, appears to be different from that caused by mediator release and may be due to an effect on sensory nerves.

Disodium pyrosulfite
Sodium metabisulphite
Disodium disulfite
Disodium metabisulfite
Sodium bisulfite anhydrous
UNII-4VON5FNS3C
sodium pyrosulphite
MFCD00167602
4VON5FNS3C
Na2S2O5

Sodium metabisulfite is an organic salt commonly use in the healthcare and food industries. 
As a food additive, Sodium metabisulfite is used as a preservative. When used as a health product it is used most often in hair care products. 
A further common use of sodium metabisulfite is as a disinfectant. 
So, is Sodium metabisulfite bad for you? Well, that depends entirely on the amount of exposure. 
The sodium metabisulfite that helps keep your food fresher longer isn't going to harm you. 
Multiple studies have been done and no carcinogenic effects have been found. 
There are some studies that indicate sulfite can cause copper levels in the kidney to rise, but any sulfite you are getting from sodium metabisulfite has been diluted far more than what was used in the experiment. 
In fact, a reaction to sodium metabisulfite will most likely occur only in people who are allergic to sulfite or in people who are exposed to pure sodium metabisulfite. 

When pure sodium metabisulfite is ingested, Sodium metabisulfite can cause gastrointestinal damage by releasing sulfurous acid as it comes into contact with stomach acid. 
Inhaled, sodium metabisulfite is a strong irritant and can cause shortness of breath and coughing. 
Sodium metabisulfite is also a skin and eye irritant . 

Preparation
When a solution of NaHSO3 (sodium bisulfite) is saturated with SO2 (sulfur dioxide) and then allowed to evaporate, a residue of sodium metabisulfite is obtained. 
The equilibrium reaction can be written as follows.
2HSO3– ⇌ S2O52- + H2O
The free sodium ions in the solution form an ionic bond with the metabisulfite ion, resulting in the formation of solid Na2S2O5 residue.

Appearance
White crystals or crystalline powder. 
Slowly oxidized to Na2SO4 (sodium sulfate) and release sulfur dioxide (SO2) gas if exposed to air and moisture. 
SO2 is also released by the reaction with acid.

Sodium metabisulfites solubility
Soluble in water and Sodium metabisulfites water solubility increases with temperature, 54g/100ml at 20°C and 81.7g/100ml at 100°C. 
Sodium metabisulfite produces sodium bisulfite (HSO3−) when dissolved in water and the aqueous solution is acidic with the PH 4.0-5.5 (10 % aqueous solution). 
Na2S2O5 + H2O = 2 NaHSO3
Soluble in glycerin, slightly soluble in ethanol, insoluble in benzene.

Sodium metabisulfites origin
Sodium metabisulfite can be produced by crystallizing a solution of sodium bisulfite. 
Sodium bisulfite results from introducing sulfur dioxide into a solution of sodium sulfite. 
Sodium sulfite, in turn, can be produced by introducing sulfur dioxide into sodium hydroxide.

Sodium metabisulfite [NF]
Disulfurous acid, sodium salt (1:2)
Fertisilo
Natrii disulfis
Campden Tablets
Sodium metabisulfite (NF)
Natrium pyrosulfit
Natriummetabisulfit
Natrium metabisulfurosum

Sodium metabisulphite is used to neutralize regular bleach that can stay in fabric even after rinsing. 
After bleaching, soaking in a solution of metabisulphite prevents the deterioration of fibers by bringing the pH back to neutral.

Sodium metabisulfite, for analysis
Sodium metabisulfite, 97+%, ACS reagent
CCRIS 3951
HSDB 378
Sodium pyrosulfite (Na2S2O5)
Sodium metabisulfite (Na2-S2O5)
Sodium metabisulfite, 97%, extra pure, anhydrous

Function
As a reducing agent, sodium metabisulfite makes the dough flexible for better sheeting, and this is the rationale for sodium metabisulfite’s working as reducing agent. 
Sodium metabisulfite reacts with the cysteine amino acids in dough, creating S-sulfocysteine residues within the protein structure, which inhibit the restoration of disulfide bonds.
Essentially, sodium metabisulfite acts as a cap, covering the reactive thiol group on cysteine, so it is unavailable to reform disulfide bonds. 
Lack of adequate disulfide bonds means that dough can’t form a strong gluten network.
Recent studies show that the presence of sodium metabisulfite slows down the Maillard reaction, thereby reducing levels of acrylamide.

Sodium Metabisulfite is generally immediately available in most volumes. 
High purity, submicron and nanopowder forms may be considered. 
American Elements produces to many standard grades when applicable, including Mil Spec (military grade); ACS, Reagent and Technical Grade; Food, Agricultural and Pharmaceutical Grade; Optical Grade, USP and EP/BP (European Pharmacopoeia/British Pharmacopoeia) and follows applicable ASTM testing standards.

Application
Compared with other reducing agents, like glutathione and L-cysteine, sodium metabisulfite has the greatest reducing capacity. 
There is far greater danger of over-dosing a formulation. 
The reducing power is one reason that sodium metabisulfite is not the preferred reducing agent in the industry. 
Sodium metabisulfite is usually used at 0.03% dry flour weight in cracker production. 
Sodium metabisulfite is rarely used in bread dough production.

Sodium Metabisulfite Na2S2O5
Molar Mass 190.107 grams per mole
Density    1.48 grams per cubic centimetre
Melting Point 170oC but begins to decompose at 150oC
Boiling Point Decomposes

Sodium metabisulfites physical properties
Sodium sulfite has a white or whitish-yellow appearance in its solid-state.
Sodium metabisulfite has a faintly pungent smell similar to SO2.
Na2S2O5 is fairly soluble in water – its solubility corresponds to 65.3g/100mL at a temperature of 20o
This compound is highly soluble in glycerol but not very soluble in ethanol.

Sodium metabisulfites chemical properties
When introduced to water, sodium metabisulfite liberates sulfur dioxide gas which has a very pungent and unpleasant odour. 
This gas can also lead to respiratory problems in humans.
SO2 gas is liberated by this compound on exposure to strong acids such as hydrochloric acid. 
The chemical equation for this reaction is given by: 2HCl + Na2S2O5 → 2SO2 + 2NaCl + H2O
When heated, sodium metabisulfite undergoes decomposition to form sodium sulfite and sulfur dioxide. 
The chemical reaction is: Na2S2O5 → SO2 + Na2SO3

Sodium metabisulfites uses
Sodium sulfite has several applications as an antioxidant, a preservative and as a disinfectant. 
Some important uses of this compound are listed below.

Na2S2O5 is one of the primary ingredients used in Campden tablets. 
Sodium metabisulfite is also used to sanitize the equipment used for winemaking.
This compound is also used to increase the shelf life of several local anaesthetics.
Concentrated Na2S2O5 can be used for the removal of tree stumps since it degrades the lignin in it.
Sodium sulfite is also used to test for sickle cell diseases.
When gold is dissolved in aqua regia, Sodium metabisulfite can be precipitated out with the help of this compound.
Since Sodium metabisulfite can act as an oxygen scavenger, Na2S2O5 is used as a corrosion inhibitor in the oil industry.
Sodium metabisulfite is also used in the treatment of wastewater since it can reduce hexavalent chromium into its trivalent form.

Compound Formula: Na2S2O5
Molecular Weight: 190.1
Appearance: White crystals or poqder
Melting Point: >300 °C
Boiling Point: N/A
Density: 1.4 g/cm3
Solubility in H2O: N/A
pH: 3.5-5.0 (20 °C, 5%)
Exact Mass: 189.898254
Monoisotopic Mass: 189.898254

Sodium Metabisulfite is an inorganic salt used as a disinfectant and preservative agent in cosmetics and personal care products. 
Sodium metabisulfite is also considered a reducing agent that donates hydrogen molecules to other substances in cosmetics and personal care products. 
Sodium metabisulfite can sometimes function as an antioxidant, preventing or slowing deterioration of formulas caused by chemical reactions with oxygen. 
Sodium Metabisulfite is seen as an ingredient primarily in hair care products, such as formulas for permanent waves, hair bleaches, hair dyes, colors and tints, and also in some bath and skin care products

What are the uses of sodium metabisulfite?
Sodium metabisulfite, a chemical compound with the formula Na2S2O5, is widely used as an antioxidant in pharmaceutical formulations. 
Sodium metabisulfite is also used as a disinfectant and as a food preservative in many industries.

List some examples of foods that contain sodium metabisulfite
Examples of food items that contain sodium metabisulfite are listed below:
-Jams
-Baked products
-Potato chips
-Pickled food items
-Dried fruits

Is sodium metabisulfite organic or inorganic?
Sodium metabisulfite, also known as sodium pyrosulfite, is an inorganic compound with the chemical formula Na2S2O5. 
The IUPAC spelling of the compound is sodium metabisulphite or sodium pyrosulphite.
Sodium metabisulfite is used as a preservative and antioxidant in food and is also known as E223. 
Sodium metabisulfite can be used to preserve color of some fruits, such as bananas. 
Sodium metabisulfite may cause allergic reactions in those who are sensitive to sulfites, including respiratory reactions in asthmatics, anaphylaxis, and other allergic reactions in sensitive individuals.
Sodium metabisulfite and potassium metabisulfite are the primary ingredients in Campden tablets, used for wine and beer making.
The acceptable daily intake is up to 0.7 milligrams per kilogram of body weight. 
Sodium metabisulfite oxidizes in the liver to harmless sulfate which is excreted in the urine.
Sodium metabisulphite is added as an excipient to medications which contain adrenaline (epinephrine), in order to prevent the oxidation of adrenaline. 
For example, Sodium metabisulfite is added to combination drug formulations which contain a local anaesthetic and adrenaline, and to the formulation in epinephrine autoinjectors, such as the EpiPen. 
This lengthens the shelf life of the formulation, although the sodium metabisulphite reacts with adrenaline, causing it to degrade and form epinephrine sulphonate.
Concentrated sodium metabisulfite can be used to remove tree stumps. 
Some brands contain 98% sodium metabisulfite, and cause degradation of lignin in the stumps, facilitating removal.
A very important health related aspect of this substance is that Sodium metabisulfite can be added to a blood smear in a test for sickle cell anaemia (and other similar forms of haemoglobin mutation). 
The substances causes defunct cells to sickle (through a complex polymerisation) hence confirming disease.

EINECS 231-673-0
AI3-51684
Disodiumdisulphite
Sodium metasulfite
sodiummetabisulphite
sodium metabisuifite
sodium metabisuiphite
sodium meta bisulfite
sodium meta-bisulfite
ACMC-1BJUM
Na2O5S2
EC 231-673-0

What is Sodium Metabisulfite?
Sodium metabisulfite is an inorganic compound composed of sodium, sulfur and oxygen. 
Sodium metabisulfite's typically a white, or yellowish-white crystalline powder that easily dissolves in water, which leaves that unpleasantly familiar sulfur smell.

In Food
Sodium metabisulfite is commonly used as a food preservative for dried foods like potato chips, raisins and apples, as well as fruit concentrate juices. 
As a food product, the safe daily intake of sodium metabisulfite has been determined to be about .
7 grams per kilogram of body weight. 
However, those with allergies to sulfites – often exhibited by rashes, hives and wheezing - may want to steer clear of this preservative altogether.

As a Cleaning Agent
The compound is also present in wines and beers, as Sodium metabisulfite's used as both a sterilizer and an antioxidant in the process of brewing beer or fermenting wine. 
If you or someone you know claims to have an allergy to red wine, Sodium metabisulfite's probably because of the presence of sodium metabisulfite.
As an antibacterial, the chemical is also used in the process of purifying water, cleaning water pipes and reverse osmosis membranes in desalinization equipment.

Additional Uses
Sodium metabisulfites acidic and preservative properties also make Sodium metabisulfite an effective substitute for sodium bisulfite, a chemical that's used in traditional darkroom photography. 
Also, sodium metabisulfite is used as a bleaching agent in pulp and textile manufacture, as well as a reducing agent in pharmaceuticals. 
Sodium metabisulfite's also a known preservative in cosmetics.
Sodium metabisulfite, in concentrated form, has also been used in landscape gardening as a tree stump remover, as it disintegrates the lignins – chemicals in plant cell walls – in the tree stumps, making them easier to remove.

Sodium pyrosulfite (JP17)
CHEMBL2016976
DTXSID0029684
CHEBI:114786
Sodium metabisulfite, SO2 58.5%
Sodium metabisulfite A.C.S. reagent
AKOS015950722
NSC 158277
NSC 227243
E223
K325
FT-0645096
disodium oxido(oxo)-kappa(4)-sulfanesulfonate
D02054
Q284549

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