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Sodium dodecyl sulfate
Sodium dodecyl sulfate (or sulphate) (SDS or NaDS) (C12H25SO4Na), is an anionic surfactant that is used in household products such as toothpastes, shampoos, shaving foams and bubble baths for its thickening effect and its ability to create a lather. The molecule has a tail of 12 carbon atoms, attached to a sulfate group, giving the molecule the amphiphilic properties required of a detergent.
It is prepared by esterification of sulfuric acid with dodecanol (lauryl alcohol, C12H25OH) followed by neutralization with sodium carbonate. It is used in both industrially produced and home-made cosmetics.
Like all detergent surfactants (including soaps), it removes oils from the skin, and can cause skin and eye irritation.
SDS can be converted by ethoxylation to sodium laureth sulfate (also called sodium lauryl ether sulfate; SLES), which is less harsh on the skin, probably because it is not as much of a protein denaturant as is the unethoxylated substance.
It is probably the most researched anionic surfactant compound.
It has recently found application as a surfactant in gas hydrate or methane hydrate formation reactions, increasing the rate of formation as much as 700 times.
Additional recommended knowledge
In laboratories, SDS is commonly used in preparing proteins for polyacrylamide gel electrophoresis (SDS-PAGE). SDS works by disrupting non-covalent bonds in the proteins, thereby denaturing them, causing the molecules to lose their native shape (conformation). Also, anions of SDS bind to the main peptide chain at a ratio of one SDS anion for every two amino acid residues. This effectively imparts a negative charge on the protein that is proportional to the mass of that protein (about 1.4 g SDS/g protein). 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.
Safety concerns relating to SDS
When handling SDS in its solid form use extreme caution, the compound easily particlizes into the air. If inhaled can cause a serious choking hazard. It is strongly advised that a dust mask and vacuum hood be used when working with the compound to minimize exposure.
A number of health concerns about SDS have been raised in published reports. These studies indicate that:
Categories: Organosulfates | Sodium compounds | Cleaning product components | Surfactants
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sodium_dodecyl_sulfate". A list of authors is available in Wikipedia.|