Sodium bisulfite
{{Distinguish|Sodium bisulfate}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 477858271
| ImageFile = Sodium bisulfite.png
| ImageSize = 140px
| ImageFile1 = Sodium-bisulfite-3D-balls.png
| ImageSize1 = 160px
| ImageName1 = Ball-and-stick model of a bisulfite anion (left) and a sodium cation (right)
| ImageFile2 = Hydrogensiřičitan sodný.jpg
| IUPACName = Sodium hydrogen sulfite
| OtherNames = {{Unbulleted list|E222|sodium bisulphite}}
|Section1={{Chembox Identifiers
| CASNo = 7631-90-5
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = TZX5469Z6I
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 26709
| PubChem = 23665763
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 571016
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 1689285
| SMILES = [Na+].[O-]S(=O)O
| InChI = 1/Na.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+1;/p-1
| InChIKey = DWAQJAXMDSEUJJ-REWHXWOFAL
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Na.H2O3S/c;1-4(2)3/h;(H2,1,2,3)/q+1;/p-1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = DWAQJAXMDSEUJJ-UHFFFAOYSA-M
| RTECS = VZ2000000
}}
|Section2={{Chembox Properties
| Formula = NaHSO3
| MolarMass = 104.061{{nbsp}}g/mol
| Appearance = White solid
| Odor = Slight sulfurous odor
| Density = 1.48{{nbsp}}g/cm3
| MeltingPtC = 150
| BoilingPtC = 315
| Solubility = 42{{nbsp}}g/100{{thinsp}}mL
| RefractIndex = 1.526
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| GHSPictograms = {{GHS07}}
| HPhrases = {{H-phrases|302}}
| PPhrases = {{P-phrases|301+312+330}}
| NFPA-H = 2
| NFPA-F = 0
| NFPA-R = 1
| FlashPt = Non-flammable
| LD50 =
| IDLH = N.D.{{PGCH|0561}}
}}
|Section8={{Chembox Related
| OtherAnions = Sodium sulfite
Sodium metabisulfite
Sodium biselenite
| OtherCations = Potassium bisulfite
}}
}}
Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO3. Sodium bisulfite is not a real compound,{{cite journal|doi=10.1021/ed080p1482|bibcode=2003JChEd..80.1482T|title=New Methods to Estimate Lattice Energies: Application to the Relative Stabilities of Bisulfite (HSO3−) and Metabisulfite (S2O52-) Salts|year=2003|last1=Tudela|first1=David|last2=Jenkins|first2=H. Donald B.|journal=Journal of Chemical Education|volume=80|issue=12|pages=1482|url=https://pubs.acs.org/doi/pdf/10.1021/ed080p1482|url-access=subscription}} but a mixture of salts that dissolve in water to give solutions composed of sodium and bisulfite ions. It appears in form of white or yellowish-white crystals with an odor of sulfur dioxide. Sodium bisulfite is used in a variety industries such as a food additive with E number E222 in the food industry. It is a reducing agent in the cosmetic and in the bleaching applications.{{cite journal |last=EFSA Panel on Food additives and Nutrient Sources added to Food (ANS) |date=2016 |title=Scientific Opinion on the re-evaluation of sulfur dioxide (E 220), sodium sulfite (E 221), sodium bisulfite (E 222), sodium metabisulfite (E 223), potassium metabisulfite (E 224), calcium sulfite (E 226), calcium bisulfite (E 227) and potassium bisulfite (E 228) as food additives |journal=EFSA Journal |volume=14 |issue=4 |doi=10.2903/j.efsa.2016.4438|doi-access=free }}
Synthesis
Sodium bisulfite solutions can be prepared by treating a solution of suitable base, such as sodium hydroxide or sodium bicarbonate with sulfur dioxide.
:SO2 + NaOH → NaHSO3
:SO2 + NaHCO3 → NaHSO3 + CO2
Attempts to crystallize the product yield sodium metabisulfite (also called sodium disulfite), Na2S2O5.{{cite book|doi=10.1002/9780470132333.ch49|isbn=9780470132333|chapter=Sulfites and Pyrosulfites of the Alkali Metals|series=Inorganic Syntheses|year=1946|last1=Johnstone|first1=H. F.|title=Inorganic Syntheses|pages=162–167|volume=2|url=https://onlinelibrary.wiley.com/doi/pdf/10.1002/9780470132333.ch49|url-access=subscription}}
Upon dissolution of the metabisulfite in water, bisulfite is regenerated:
:Na2S2O5 + H2O → 2 Na+ + 2 HSO3−
Sodium bisulfite is formed during the Wellman-Lord process.{{cite book | chapter-url = https://books.google.com/books?id=rfSItUDqX9sC&pg=PA554 |chapter-url-access=subscription| title = Gas Purification | chapter = Sulfur Dioxide Removal | first = Arthur L. | last = Kohl |author2=Nielsen, Richard B. | publisher = Gulf Professional Publishing | year = 1997 | isbn = 978-0-88415-220-0 | pages =554–555}}
Uses
=Cosmetics=
Sodium bisulfite functions as a hair-waving/straightening agent.{{cite journal |last1=Leite |first1=Marcella Gabarra Almeida |last2=Garbossa |first2=Wanessa Almeida Ciancaglio |last3=Campos |first3=Patricia Maria Berardo Gonçalves Maia |date=2018-11-29 |title=Hair straighteners: an approach based on science and consumer profile |journal=Brazilian Journal of Pharmaceutical Sciences |volume=54 |issue=3 |doi=10.1590/s2175-97902018000317339 |issn=2175-9790|doi-access=free }} As of 1998, sodium bisulfite was used in 58 cosmetic products including hair conditioners, moisturizers, and hair dyes.{{cite journal |last1=Cherian |first1=Priya |last2=Zhu |first2=Jinqiu |last3=Bergfeld |first3=Wilma F. |last4=Belsito |first4=Donald V. |last5=Hill |first5=Ronald A. |last6=Klaassen |first6=Curtis D. |last7=Liebler |first7=Daniel C. |last8=Marks |first8=James G. |last9=Shank |first9=Ronald C. |last10=Slaga |first10=Thomas J. |last11=Snyder |first11=Paul W. |date=2020 |title=Amended Safety Assessment of Parabens as Used in Cosmetics |url=http://dx.doi.org/10.1177/1091581820925001 |journal=International Journal of Toxicology |volume=39 |issue=1_suppl |pages=5S–97S |doi=10.1177/1091581820925001 |pmid=32723119 |s2cid=220850521 |issn=1091-5818}}
=Food industry=
Sodium bisulfite is used to prevent discoloration, bleach food starches, and delay spoilage of the product. In the US, EPA, FDA, and American Conference of Governmental Industrial Hygienists established a working place threshold limit value for sulfur dioxide of 2ppm averaged over 8 hours, and a 3-hour level of 5ppm. Even with this threshold established, the FDA recognized sodium bisulfite as "generally recognized as safe" compound.
Sulfites in food can be assayed by the Monier-Williams type procedure,{{cite journal |title=Reevaluation of Monier-Williams method for determining sulfite in food |url=https://academic.oup.com/jaoac/article-abstract/69/1/3/5697566 |access-date=2022-09-20 |publisher=Oxford University Press|journal=Journal of AOAC International}} HPLC after extraction, and Flow Injection analysis.
=Textile industry=
Sodium bisulfite is used as an antichlor in the textile industry.{{cite journal |date=2003-06-01 |title=Final Report on the Safety Assessment of Sodium Sulfite, Potassium Sulfite, Ammonium Sulfite, Sodium Bisulfite, Ammonium Bisulfite, Sodium Metabisulfite and Potassium Metabisulfite |url=http://ijt.sagepub.com/cgi/doi/10.1080/10915810390239478 |journal=International Journal of Toxicology |language=en |volume=22 |issue=2 Suppl |pages=63–88 |doi=10.1080/10915810305077X |pmid=14555420 |issn=1091-5818|last1=Nair |first1=B. |last2=Elmore |first2=A. R. |author3=Cosmetic Ingredients Review Expert Panel }}{{Citation |last1=Periyasamy |first1=A.P. |title=Denim processing and health hazards |date=2017 |url=https://linkinghub.elsevier.com/retrieve/pii/B9780081020432000071 |work=Sustainability in Denim |pages=161–196 |publisher=Elsevier |language=en |doi=10.1016/b978-0-08-102043-2.00007-1 |isbn=978-0-08-102043-2 |access-date=2022-05-11 |last2=Militky |first2=J.|url-access=subscription}} Antichlors are very useful in the textile industry because bleaching of compounds using chlorine is a standard practice.
Safety
The International Agency for Research on Cancer concluded that there was inadequate evidence that sodium bisulfite was carcinogenic. Under specific conditions such as acidity and concentration level, sodium bisulfite was able to cause negative alterations to the genome such as catalyzing transamination, and to induce sister-chromatid exchanges suggesting possible genotoxicity.{{cite journal |last1=Abe |first1=Syuiti |last2=Sasaki |first2=Motomichi |date=1977 |title=Chromosome Aberrations and Sister Chromatid Exchanges in Chinese Hamster Cells Exposed to Various Chemicals 2 |url=https://academic.oup.com/jnci/article-lookup/doi/10.1093/jnci/58.6.1635|url-access=subscription |journal=Journal of the National Cancer Institute |language=en |volume=58 |issue=6 |pages=1635–1641 |doi=10.1093/jnci/58.6.1635 |pmid=864744 |issn=1460-2105}} In a study using Osbourne-Mendel strain rats, it was concluded that oral toxicity was not significant if the consumed concentration was less than 0.1% (615 ppm as SO2).{{cite journal |last1=Jonker |first1=D. |last2=Woutersen |first2=R.A. |last3=van Bladeren |first3=P.J. |last4=Til |first4=H.P. |last5=Feron |first5=V.J. |date=1990 |title=4-Week oral toxicity study of a combination of eight chemicals in rats: Comparison with the toxicity of the individual compounds |url=https://linkinghub.elsevier.com/retrieve/pii/027869159090170R |url-access=subscription|journal=Food and Chemical Toxicology |language=en |volume=28 |issue=9 |pages=623–631 |doi=10.1016/0278-6915(90)90170-R|pmid=2272560 }} A study by Servalli, Lear, and Cottree in 1984 found that sodium bisulfite did not produce membrane fusion in hepatic and murine glial cells and human fibroblasts, so there is no oral toxicity. These clinical studies concluded that sodium bisulfite was safe to use in cosmetic formulations.
The concentrations of sodium bisulfite that could be dangerous are well beyond the concentrations discussed in the cosmetic and food industry..{{cite journal |last1=Nagayama |first1=Hirotoshi |last2=Hatamochi |first2=Atsushi |last3=Shinkai |first3=Hiroshi |date=1997 |title=A Case of Contact Dermatitis Due to Sodium Bisulfite in an Ophthalmic Solution |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1346-8138.1997.tb02315.x|url-access=subscription |journal=The Journal of Dermatology|language=en |volume=24 |issue=10 |pages=675–677 |doi=10.1111/j.1346-8138.1997.tb02315.x|pmid=9375469 |s2cid=21945156 }}
The World Health Organization Expert Committee on Food Additives concluded that 0-0.7mg of sulfur dioxide equivalent/kg of body weight per day will cause no harm to an individual consuming this compound as a food additive. Sulfites exhibit no genotoxicity and carcinogenicity.