Sodium dodecyl sulfate
|Sodium lauryl sulfate|
|Jmol-3D images||Image 1|
|Molar mass||288.372 g/mol|
|Appearance||white or cream-colored solid|
|Melting point||206 °C (403 °F; 479 K)|
|Refractive index (nD)||1.461|
|LD50||1288 mg/kg (rat, oral)|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Sodium dodecyl sulfate (SDS or NaDS), sodium laurilsulfate or sodium lauryl sulfate (SLS) is an organic compound with the formula CH3(CH2)11OSO3Na. It is an anionic surfactant used in many cleaning and hygiene products. The salt is of an organosulfate consisting of a 12-carbon tail attached to a sulfate group, giving the material the amphiphilic properties required of a detergent. Derived from inexpensive coconut and palm oils, it is a common component of many domestic cleaning products.
SDS is synthesized by treating lauryl alcohol with sulfur trioxide gas, oleum, or chlorosulfuric acid to produce hydrogen lauryl sulfate. The industrially practiced method typically uses sulfur trioxide gas. The resulting product is then neutralized through the addition of sodium hydroxide or sodium carbonate. Lauryl alcohol is in turn usually derived from either coconut or palm kernel oil by hydrolysis, which liberates their fatty acids, followed by hydrogenation.
SDS is available commercially in powder and pellet forms. It seems the pellet form dissolves faster than the powder form in water.
SDS is mainly used in detergents for laundry with many cleaning applications. SDS is a highly effective surfactant and is used in any task requiring the removal of oily stains and residues. For example, it is found in higher concentrations with industrial products including engine degreasers, floor cleaners, and car wash soaps. It is found in toothpastes, shampoos, shaving creams, and bubble bath formulations in part for its thickening effect and its ability to create a lather. Pepsodent toothpaste at one time used the name "Irium" for its sodium lauryl sulfate ingredient.
It can be used to aid in lysing cells during DNA extraction and for unraveling proteins in SDS-PAGE. Sodium lauryl sulfate, in science referred to as sodium dodecyl sulfate (SDS) or Duponol, is commonly used in preparing proteins for electrophoresis in the SDS-PAGE technique. This compound works by disrupting non-covalent bonds in the proteins, denaturing them, and causing the molecules to lose their native shape (conformation).
This new negative charge is significantly greater than the original charge of that protein. The electrostatic repulsion that is created by binding of SDS causes proteins to unfold into a rod-like shape thereby eliminating differences in shape as a factor for separation in the gel.
Sodium lauryl sulfate is probably the most researched anionic surfactant compound. Like all detergent surfactants, sodium lauryl sulfate removes oils from the skin, and can cause skin and eye irritation. The critical micelle concentration (CMC) in pure water at 25 °C is 8.2 mM, and the aggregation number at this concentration is usually considered to be about 62. The micelle ionization fraction (α) is around 0.3 (or 30%).
Aqueous solutions of SDS are also popular for dispersing or suspending nanotubes, such as carbon nanotubes (CNTs). However, sodium dodecylbenzene sulfonate (NaDDBS) and Triton X-100 are reported to be better dispersants of single walled carbon nanotubes.
Sodium lauryl sulfate is also used in the analysis of hemoglobin. The hydrophobic group of SLS acts upon the globin subunit, causing a conformational change. The hydrophillic group of SLS then binds with the oxidized iron subunit, producing a stable reaction product which can then be analyzed, giving a hemoglobin value which is used as part of a complete blood count.
Sodium dodecyl sulfate is also used to clear brain tissue, by removing lipids responsible for light scattering. Biological tissues treated by sodium dodecyl sulfate are rendered quasi-transparent in optical microscopy, enabling to see through them.
SDS represents a potentially effective topical microbicide, which can also inhibit and possibly prevent infection by various enveloped and non-enveloped viruses such as the Herpes simplex viruses, HIV, and the Semliki Forest Virus.
Evidence suggests that surfactants such as sodium lauryl sulfate can act as a shark repellent at concentrations on the order of 100 parts per million. However, this does not meet the desired "cloud" deterrence level of 0.1 parts per million.
Some species of flies, ants, and moths are attracted to sodium lauryl sulfate or anionic surfactant, even in small amounts, and are then killed by it. It is the main active ingredient in most store-bought house fly killers. House flies are more commonly attracted to it, however, if the chemical is in a sweet-smelling soap or bleach detergent.
SDS is not carcinogenic when either applied directly to skin or consumed. A review of the scientific literature stated "SLS [SDS] was negative in an Ames (bacterial mutation) test, a gene mutation and sister chromatid exchange test in mammalian cells, as well as in an in vivo micronucleus assay in mice. The negative results from in vitro and in vivo studies indicate SDS does not interact with DNA." The same review also stated "In the only carcinogenicity study available, SDS was not carcinogenic in Beagle dogs, though the short study duration and limited details provided limit the significance that can be attached to the data."
It has been shown to irritate the skin of the face, with prolonged and constant exposure (more than an hour) in young adults. SDS may worsen skin problems in individuals with chronic skin hypersensitivity, with some people being affected more than others. In animal studies SDS appears to cause skin and eye irritation.
SDS can contact the face from aerosolized dust during SDS reparation for laboratory purposes. To prevent contact with face and eyes, a dust-free “pellet” form of SDS is available which essentially eliminates SDS dust inhalation and contact with the face.
There have been several studies on how SDS in toothpaste affects the recurrence of aphthous ulcers, commonly referred to in some countries as canker sores or white sores. The results of these studies have been inconsistent.
In 1994, a preliminary crossover study showed patients had a significantly higher number of aphthous ulcers after using SLS-containing toothpaste, compared with an SLS-free toothpaste. A follow-up double-blind crossover study in 1996 further supported these results, as did a separate study in 1997.
However, a double-blind crossover study published in 1999 failed to find any statistically significant difference. A double-blind crossover study in 2012 also failed to find a significant difference in number of ulcers, but did find a significant difference in ulcer duration and pain scores. According to the 2012 study, patients using an SLS-free toothpaste experienced faster healing of ulcers and less ulcer-related pain on average than patients using SLS-containing toothpaste.
Interaction with fluoride
Some studies have suggested that SLS in toothpaste may decrease the effectiveness of fluoride at preventing dental caries (cavities). This may be due to SLS interacting with the deposition of fluoride on tooth enamel.
- "Sodium Coco-Sulfate". TightlyCurly.com. Retrieved 26 March 2012.
- LaFlesh, Teri (2010). Curly Like Me: How to Grow Your Hair Healthy, Long, and Strong. John Wiley & Sons. p. 189.
- European Pharmacopoeia: Sodium laurilsulfate
- "Sodium dodecyl sulfate, DF (Dust-free grade)". Retrieved 20 April 2012.
- Eduard Smulders, Wolfgang Rybinski, Eric Sung, Wilfried Rähse, Josef Steber, Frederike Wiebel, Anette Nordskog, "Laundry Detergents" in Ullmann’s Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a08_315.pub2
- Household Products Database of products containing sodium lauryl sulfate
- The acronym expands to "sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
- P. Mukerjee and K. J. Mysels, "Critical Micelle Concentration of Aqueous Surfactant Systems", NSRDS-NBS 36, US. Government Printing Office, Washington, D.C., 197 1.
- N.J. Turro. A. Yekta, J. Am. Chem. Soc., 1978, 100, 5951
- Barney L. Bales, Luis Messina, Arwen Vidal, Miroslav Peric, and Otaciro Rangel Nascimento (1998). "Precision Relative Aggregation Number Determinations of SDS Micelles Using a Spin Probe. A Model of Micelle Surface Hydration". J. Phys. Chem. B 102 (50): 10347–10358. doi:10.1021/jp983364a.
- Islam, M. F. "High Weight Fraction Surfactant Solubilization of Single-Wall Carbon Nanotubes in Water". Nano Letters 3 (2): 269–273. doi:10.1021/nl025924u.
- Shen, Helen. "See-through brains clarify connections". Structural and molecular interrogation of intact biological systems. Nature Publishing. Retrieved 12 April 2013.
- Piret J, Désormeaux A, Bergeron MG. (2002). "Sodium lauryl sulfate, a microbicide effective against enveloped and nonenveloped viruses.". Curr Drug Targets 3 (1): 17–30. doi:10.2174/1389450023348037. PMID 11899262.
- Piret J, Lamontagne J, Bestman-Smith J, Roy S, Gourde P, Désormeaux A, Omar RF, Juhász J, Bergeron MG. (2000). "In vitro and in vivo evaluations of sodium lauryl sulfate and dextran sulfate as microbicides against herpes simplex and human immunodeficiency viruses.". J Clin Microbiol 38 (1): 110–9. PMC 86033. PMID 10618073.
- Joseph A. Sisneros and Donald R. Nelson (2001). "The effectiveness of sodium lauryl sulphate as a shark repellent in a laboratory test situation". Environmental Biology of Fishes 60: 117–130. doi:10.1023/A:1007612002903.
- Larry J. Smith Jr. (January 1991). "Surfactants as chemical shark repellents: past, present, and future". Journal of Fish Biology 38 (1): 105–113. doi:10.1111/j.1095-8649.1991.tb03096.x. Retrieved 2010-08-27.
- Adams, Michael J. Characterization and Measurement of Flavor Compounds: Substances That Modify the Perception of Sweetness. ACS Publications, 1985, p.11-25. Abstract online at http://pubs.acs.org/doi/abs/10.1021/bk-1985-0289.ch002
- Clark, Josh. "Why does orange juice taste bad after you brush your teeth?" Discovery Health. http://health.howstuffworks.com/wellness/beauty-hygiene/orange-juice-toothpaste.htm
- CIR publication (1983). "Final Report on the Safety Assessment of Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate". International Journal of Toxicology 2 (7): 127–181. doi:10.3109/10915818309142005..
- NICNAS – Sodium Lauryl Sulfate
- Marrakchi S, Maibach HI (2006). "Sodium lauryl sulfate-induced irritation in the human face: regional and age-related differences". Skin Pharmacol Physiol 19 (3): 177–80. doi:10.1159/000093112. PMID 16679819.
- Agner T (1991). "Susceptibility of atopic dermatitis patients to irritant dermatitis caused by sodium lauryl sulphate". Acta Derm. Venereol. 71 (4): 296–300. PMID 1681644.
- Nassif A, Chan SC, Storrs FJ, Hanifin JM (November 1994). "Abnormal skin irritancy in atopic dermatitis and in atopy without dermatitis". Arch Dermatol 130 (11): 1402–7. doi:10.1001/archderm.130.11.1402. PMID 7979441.
- Löffler H, Effendy I (May 1999). "Skin susceptibility of atopic individuals". Contact Derm. 40 (5): 239–42. doi:10.1111/j.1600-0536.1999.tb06056.x. PMID 10344477.
- Herlofson BB, Barkvoll P (October 1994). "Sodium lauryl sulfate and recurrent aphthous ulcers. A preliminary study". Acta Odontol. Scand. 52 (5): 257–9. doi:10.3109/00016359409029036. PMID 7825393.
- Herlofson BB, Barkvoll P (June 1996). "The effect of two toothpaste detergents on the frequency of recurrent aphthous ulcers". Acta Odontol. Scand. 54 (3): 150–3. doi:10.3109/00016359609003515. PMID 8811135.
- Chahine L, Sempson N, Wagoner C (December 1997). "The effect of sodium lauryl sulfate on recurrent aphthous ulcers: a clinical study". Compend Contin Educ Dent 18 (12): 1238–40. PMID 9656847.
- Healy CM, Paterson M, Joyston-Bechal S, Williams DM, Thornhill MH (January 1999). "The effect of a sodium lauryl sulfate-free dentifrice on patients with recurrent oral ulceration". Oral Dis. 5 (1): 39–43. doi:10.1111/j.1601-0825.1999.tb00062.x. PMID 10218040.
- Shim, Y. J.; Choi, J. -H.; Ahn, H. -J.; Kwon, J. -S. (2012). "Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: A randomized controlled clinical trial". Oral Diseases: no. doi:10.1111/j.1601-0825.2012.01920.x. PMID 22435470.
- Julie Deardorff (March 5, 2014). "Loss of canker sore toothpaste angers loyal users". Chicago Tribune. Retrieved April 12, 2014.
- Joe Graedon, MS, Teresa Graedon. The People's Pharmacy Guide to Home and Herbal Remedies. Retrieved April 13, 2014.
- Barkvoll, P. (1989). "Should toothpastes foam? Sodium lauryl sulfate--a toothpaste detergent in focus". Den Norske tannlaegeforenings tidende 99 (3): 82–84. PMID 2696932.