Sodium dodecyl sulfate

Description

Sodium dodecyl sulfate (SDS), also known as Sodium lauryl sulfate (SLS) is an anionic surfactant naturally derived from coconut or palm kernel oil. It typically consists of a mixture of sodium alkyl sulfates, primarily lauryl. SLS is used in shampoos, toothpastes, facial cleansers, and many other toiletries. This amphiphilic molecule provides foaming and degreasing properties to these products. It is also used in creams and pastes in order to properly disperse ingredients and as a research tool in protein biochemistry. SLS also has some bactericidal activity.

Description

Sodium dodecyl sulfate is an anionic surfactant, and is a typical representative of sulphate-based surfactant. It is abbreviated as SDS, and also known as AS, K12, coco alcohol sulfate, sodium lauryl sulfate and foaming agent. The commercial products are usually white to light yellow crystalline powder. It is non-toxic, slightly soluble in alcohol, insoluble in chloroform and ether, soluble in water, and has good anionic and nonionic complex compatibility. It has good emulsibility, foamability, and foaming, infiltrating, decontaminating and dispersing properties. It is abundant in foams and quickly biodegradable, and has solubility next only to fatty alcohol polyoxyethylene ether sodium sulphate (abbreviated as AES). It is not sensitive to alkali and hard water, but its stability is inferior to general sulfonate under acidic conditions and is close to AES. It is not favorable to exceed 95 °C upon long-term heating, and its irritation is at the middle level among surfactants, with an irritation index of 3.3 for a 10% solution, which is higher than AES and lower than sodium dodecyl benzene sulfonate (abbreviated as LAS). Toxicity LD50 is 1300mg/kg. There is no evidence that this product is carcinogenic, but high doses may indeed irritate the skin. However, in general sanitary products the concentration is limited when used as a forming agent, and is in line with national standards. So there is no need to concern.
Sodium dodecyl sulfate is a major component of detergent. It is usually used in the DNA extraction process to separate DNA after protein denaturation. It is often misread as sodium dodecyl sulfonate. It is widely used as a foaming agent in toothpaste, soap, shower gel, shampoo, detergent and cosmetics. 95% of personal care products and household cleaning products contain sodium lauryl sulfate.
The above information is edited by the chemicalbook of Jin Yinxue.

Chemical properties

Sodium lauryl sulfate consists of white or cream to pale yellow coloured crystals, flakes, or powder having a smooth feel, a soapy, bitter taste, and a faint odor of fatty substances. It is easily soluble in water.

The Uses of Sodium dodecyl sulfate

Sodium dodecyl sulfate is an emulsifier and whipping aid that has a solubility of 1 g in 10 ml of water. It functions as an emulsifier in egg whites. It is used as a whipping aid in marshmallows and angel food cake mix. It also functions to aid in dissolving fumaric acid.

The Uses of Sodium dodecyl sulfate

Wetting agent, detergent, especially in the textile industry. Electrophoretic separation of proteins and lipids. Ingredient of toothpastes.

What are the applications of Application

Sodium dodecyl sulfate is an anionic detergent and protein denaturant. It can be used for the following applications:
(1) SDS-polyacrylamide gel electrophoresis (SDS-PAGE)
(2) Chromatin immunoprecipitation
(3) as a component of radioimmunoprecipitation assay buffer for immunoblotting
(4) As an anionic detergent

Definition

ChEBI: Sodium dodecyl sulfate is an organic sodium salt that is the sodium salt of dodecyl hydrogen sulfate. It has a role as a detergent and a protein denaturant. It contains a dodecyl sulfate.

Production Methods

Sodium lauryl sulfate is prepared by sulfation of lauryl alcohol, followed by neutralization with sodium carbonate.

What are the applications of Application

Sodium dodecyl sulfate(151-21-3) has excellent detergency, emulsification and foaming power, can be used as detergents and textile auxiliaries, and is also used as an anionic surfactant, toothpaste foaming agent, mine fire extinguishing agents, foaming agents for fire extinguishers, emulsion polymerization emulsifiers, emulsifying and dispersing agents for medical use, shampoo and other cosmetic products, wool detergent, detergent for silky class fine fabrics and flotation agent for metal beneficiation.
GB 2760-96 stipulates as processing aids for food industry. It used as foaming agents; emulsifying agents; and anionic surfactants. It is used for cakes, drinks, proteins, fruits, fruit juice, and edible oil, and so on.
It is used as surfactants, detergents, foaming agents, and wetting agents, and so on.
It is used as relatively low-level ion-pairing reagents, and is cheaper than sodium heptanesulfonate and sodium pentanesulfonate when less demanding.
It is used as raw material for modifying materials.
It is used as additives in capillary electrophoresis analysis and is generally used as molar solution.
It is also used in other analysis such as flow column analysis.

Preparation

Sodium dodecyl sulfate can be synthesized by reacting dodecyl alcohol with sulfur trioxide gas, followed by neutralization with sodium hydroxide. The preparation of SDS involves the following steps: The reaction takes place in a vertical reactor at 32 °C. Nitrogen gas is introduced through the gas vents at a flow rate of 85.9 L/min. Lauryl alcohol is added at a flow rate of 58 g/min at 82.7 kPa. Liquid sulfur trioxide is fed into the flash evaporator at 124.1 kPa, with a flow rate of 0.9072 kg/h and a flash temperature of 100 °C. The sulfated product is quickly cooled to 50 °C, aged for 10-20 min, then neutralized with a base in a neutralization kettle controlled at 50 °C. The pH is adjusted to 7-8.5, and the liquid product is spray dried to obtain a solid product.

General Description

White to pale yellow paste or liquid with a mild odor. Sinks and mixes with water.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

DODECYL SULFATE is incompatible with strong oxidizers. Sodium dodecyl sulfate is also incompatible with cationic materials and with acids with pH below 2.5. Salts, basic, such as DODECYL SULFATE, are generally soluble in water. The resulting solutions contain moderate concentrations of hydroxide ions and have pH's greater than 7.0. They react as bases to neutralize acids. These neutralizations generate heat, but less or far less than is generated by neutralization of the bases in reactivity group 10 (Bases) and the neutralization of amines. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible.

Health Hazard

Inhalation of dust causes sneezing and coughing. Ingestion of large amounts causes irritation of stomach. Dust irritates eyes and may cause burns on prolonged contact. Contact with skin causes some irritation; continued exposure to water solution causes drying out and cracking.

Fire Hazard

Flash point data for Sodium dodecyl sulfate are not available; however, Sodium dodecyl sulfate is probably combustible.

Pharmaceutical Applications

Sodium lauryl sulfate is an anionic surfactant employed in a wide range of nonparenteral pharmaceutical formulations and cosmetics.
It is a detergent and wetting agent effective in both alkaline and acidic conditions. In recent years it has found application in analytical electrophoretic techniques: SDS (sodium dodecyl sulfate) polyacrylamide gel electrophoresis is one of the more widely used techniques for the analysis of proteins; and sodium lauryl sulfate has been used to enhance the selectivity of micellar electrokinetic chromatography (MEKC).

Contact allergens

This anionic detergent is widely used in cosmetics and industry. As a skin irritant agent, SLS can be used in several dermatological applications. It is also a good indicator of excited skin during patch testing.

Biochem/physiol Actions

Sodium dodecyl sulphate?(SDS) helps to quickly disrupt the biological membranes. It is usually used as one of the major constituent of several reagents, that are used to purify nucleic acids. SDS can block the activity of RNase and deoxyribonuclease (DNase).

Safety Profile

Poison by intravenous and intraperitoneal routes. Moderately toxic by ingestion. An experimental teratogen. A human skin irritant. An experimental eye and severe skin irritant. A mild allergen. Mutation data reported. When heated to decomposition it emits toxic fumes of SO, and Na2O. See also ESTERS and SULFATES.

Safety

Sodium lauryl sulfate is widely used in cosmetics and oral and topical pharmaceutical formulations. It is a moderately toxic material with acute toxic effects including irritation to the skin, eyes, mucous membranes, upper respiratory tract, and stomach. Repeated, prolonged exposure to dilute solutions may cause drying and cracking of the skin; contact dermatitis may develop.(3) Prolonged inhalation of sodium lauryl sulfate will damage the lungs. Pulmonary sensitization is possible, resulting in hyperactive airway dysfunction and pulmonary allergy. Animal studies have shown intravenous administration to cause marked toxic effects to the lung, kidney, and liver. Mutagenic testing in bacterial systems has proved negative.
Adverse reactions to sodium lauryl sulfate in cosmetics and pharmaceutical formulations mainly concern reports of irritation to the skin or eyes following topical application.
Sodium lauryl sulfate should not be used in intravenous preparations for humans. The probable human lethal oral dose is 0.5–5.0 g/kg body-weight.
LD50 (mouse, IP): 0.25 g/kg
LD50 (mouse, IV): 0.12 g/kg
LD50 (rat, oral): 1.29 g/kg
LD50 (rat, IP): 0.21 g/kg
LD50 (rat, IV): 0.12 g/kg

storage

Sodium lauryl sulfate is stable under normal storage conditions. However, in solution, under extreme conditions, i.e. pH 2.5 or below, it undergoes hydrolysis to lauryl alcohol and sodium bisulfate.
The bulk material should be stored in a well-closed container away from strong oxidizing agents in a cool, dry place.

Purification Methods

Purify this detergent by Soxhlet extraction with pet ether for 24hours, followed by dissolution in acetone/MeOH/H2O 90:5:5(v/v) and recrystallisation [Politi et al. J Phys Chem 89 2345 1985]. It has been purified by two recrystallisations from absolute EtOH, aqueous 95% EtOH, MeOH, isopropanol or a 1:1 mixture of EtOH/isopropanol to remove dodecanol, and dried under vacuum [Ramesh & Labes J Am Chem Soc 109 3228 1987]. SDS has also been purified by repeatedly foaming whereby a 0.15% aqueous solution is made to foam and the foam is discarded, then the H2O is removed in vacuo and the residue is diluted to the required concentrations [see Cockbain & McMullen Trans Faraday Soc 47 322 1951] or by liquid-liquid extraction [see Harrold J Colloid Sci 15 280 1960]. Dry it over silica gel. For DNA work it should be dissolved in excess MeOH passed through an activated charcoal column and evaporated until it crystallises out. It has also been purified by dissolving in hot 95% EtOH (14mL/g), filtering and cooling, then drying in a vacuum desiccator. Alternatively, it is crystallised from H2O, vacuum dried, washed with anhydrous Et2O and dried in vacuum again. These operations are repeated five times [Maritato J Phys Chem 89 1341 1985, Lennox and McClelland J Am Chem Soc 108 3771 1986, Dressik J Am Chem Soc 108 7567 1986]. [Beilstein 1 IV 1847.]

Properties and Applications

INDEX/GRADE	SPECIFICATION
Appearance	Needle form without hard lumps
Active matter	92% min
Petroleum eth soluble substances	1.5% max
Inorganic salts (NaCl+Na 2 SO 4 )	5.5% max
Water	5.0% max
pH value (1% aq. solution)	7.5-9.5
Whiteness (WG)	80 min
Heavy metal	20ppm max
As	3ppm max

Incompatibilities

Sodium lauryl sulfate reacts with cationic surfactants, causing loss of activity even in concentrations too low to cause precipitation. Unlike soaps, it is compatible with dilute acids and calcium and magnesium ions.
Sodium lauryl sulfate is incompatible with salts of polyvalent metal ions, such as aluminum, lead, tin or zinc, and precipitates with potassium salts. Solutions of sodium lauryl sulfate (pH 9.5–10.0) are mildly corrosive to mild steel, copper, brass, bronze, and aluminum.

Regulatory Status

GRAS listed. Included in the FDA Inactive Ingredients Database (dental preparations; oral capsules, suspensions, and tablets; topical and vaginal preparations). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.