Name: Sodium Lauryl Sulfate
CAS No: Sulfuric acid monododecyl ester sodium salt (1 : 1) [151-21-3]
BP: Sodium Lauryl Sulphate JP: Sodium Lauryl Sulfate PhEur: Sodium Laurilsulfate USP-NF: Sodium Lauryl Sulfate
Dodecyl alcohol hydrogen sulfate, sodium salt; dodecyl sodium sulfate; dodecylsulfate sodium salt; Elfan 240; lauryl sodium sulfate; lauryl sulfate, sodium salt; monododecyl sodium sulfate; natrii laurilsulfas; sodium dodecyl sulfate; sodium n-dodecyl sulfate; sodium laurilsulfate; sodium monododecyl sulfate; sodium monolauryl sulfate; SDS; SLS; sulfuric acid monododecyl ester, sodium salt; Texapon K12P.
Sulfuric acid monododecyl ester sodium salt (1 : 1) [151-21-3]
C12H25NaO4S 288.38 The USP32–NF27 describes sodium lauryl sulfate as a mixture of sodium alkyl sulfates consisting chiefly of sodium lauryl sulfate [CH3(CH2)10CH2OSO3Na]. The PhEur 6.0 states that sodium lauryl sulfate should contain not less than 85% of sodium alkyl sulfates calculated as C12H25NaO4S.
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;(1) and sodium lauryl sulfate has been used to enhance the selectivity of micellar electrokinetic chromatography (MEKC).(2)
Sodium lauryl sulfate consists of white or cream to pale yellowcolored crystals, flakes, or powder having a smooth feel, a soapy, bitter taste, and a faint odor of fatty substances.
See Table II.
Acidity/alkalinity pH = 7.0–9.5 (1% w/v aqueous solution) Acid value 0 Antimicrobial activity Sodium lauryl sulfate has some bacteriostatic action against Gram-positive bacteria but is ineffective against many Gram-negative microorganisms. It potentiates the fungicidal activity of certain substances such as sulfanilamide and sulfathiazole. Critical micelle concentration 8.2 mmol/L (2.365 g/L) at 208C Density 1.07 g/cm3 at 208C HLB value 40 Interfacial tension 11.8 mN/m (11.8 dynes/cm) for a 0.05% w/v solution (unspecified nonaqueous liquid) at 308C. Melting point 204–2078C (for pure substance) Moisture content 45%; sodium lauryl sulfate is not hygroscopic. NIR spectra see Figure 1. Solubility Freely soluble in water, giving an opalescent solution; practically insoluble in chloroform and ether. Spreading coefficient 7.0 (0.05% w/v aqueous solution) at 308C Surface tension 25.2 mN/m (25.2 dynes/cm) for a 0.05% w/v aqueous solution at 308C Wetting time (Draize test) 118 seconds (0.05% w/v aqueous solution) at 308C
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.
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.
Sodium lauryl sulfate is prepared by sulfation of lauryl alcohol, followed by neutralization with sodium carbonate.
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.(4) Adverse reactions to sodium lauryl sulfate in cosmetics and pharmaceutical formulations mainly concern reports of irritation to the skin(3,5–7) or eyes(8) 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(9) 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
Observe normal precautions appropriate to the circumstances and quantity of material handled. Inhalation and contact with the skin and eyes should be avoided; eye protection, gloves, and other protective clothing, depending on the circumstances, are recommended. Adequate ventilation should be provided or a dust respirator should be worn. Prolonged or repeated exposure should be avoided. Sodium lauryl sulfate emits toxic fumes on combustion.
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.
Cetostearyl alcohol; cetyl alcohol; magnesium lauryl sulfate; wax, anionic emulsifying. Magnesium lauryl sulfate Empirical formula C12H26O4SHMg CAS number [3097-08-3] Comments A soluble tablet lubricant.(10) The EINECS number for magnesium lauryl sulfate is 221-450-6.
Sodium lauryl sulfate is one of the materials that have been selected for harmonization by the Pharmacopeial Discussion Group. For further information see the General Information Chapter <1196> in the USP32–NF27, the General Chapter 5.8 in PhEur 6.0, along with the ‘State of Work’ document on the PhEur EDQM website, and also the General Information Chapter 8 in the JP XV. A specification for sodium lauryl sulfate is contained in the Food Chemicals Codex (FCC).(11) The EINECS number for sodium lauryl sulfate is 205-788-1. The PubChem Compound ID (CID) for sodium lauryl sulfate is 3423265.