- Sodium dodecyl sulfate (SDS), also known as Sodium lauryl sulfate (SLS), is a widely used anionic surfactant with the chemical formula C₁₂H₂₅SO₄Na. It is derived from lauryl alcohol, which is typically obtained from coconut oil or palm kernel oil, and is chemically treated with sulfuric acid followed by neutralization with sodium hydroxide to form the sulfate salt. In its pure form, SDS appears as a white or off-white powder or crystalline solid, but in consumer and industrial products, it is usually found as a concentrated aqueous solution.
- Sodium dodecyl sulfate is valued for its strong detergent and foaming properties, which make it a common ingredient in a wide range of personal care products, such as shampoos, toothpastes, body washes, facial cleansers, and bubble baths. It is also found in household cleaning products, including laundry detergents, dishwashing liquids, and surface cleaners. SDS works by lowering the surface tension of water, allowing it to more effectively remove oils, dirt, and grease from surfaces and skin. It forms micelles around oily particles, suspending them in water and allowing them to be rinsed away.
- In cosmetics and pharmaceuticals, SDS serves not only as a cleanser but also as a wetting agent, emulsifier, and solubilizer, helping to disperse ingredients evenly throughout a formulation. In laboratories, sodium dodecyl sulfate is used in protein denaturation, most notably in SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis), a technique used to analyze protein structure and purity by imparting uniform negative charge to proteins.
- Despite its efficacy, SDS has been the subject of controversy and concern, particularly regarding skin irritation. It is a known skin and eye irritant, especially at higher concentrations or with prolonged exposure. While it is not classified as carcinogenic by major health authorities, some consumers prefer to avoid it due to its potential to disrupt the skin barrier and cause dryness or sensitivity, especially in people with preexisting skin conditions such as eczema or rosacea. Regulatory agencies such as the U.S. FDA and the European Commission permit its use within specific concentration limits, and manufacturers often mitigate irritation by combining SDS with milder co-surfactants.
- Environmentally, sodium dodecyl sulfate is biodegradable, but as with many surfactants, there are concerns about aquatic toxicity at high concentrations, especially near industrial discharge points. Nonetheless, its environmental footprint is relatively modest when used appropriately and processed through wastewater treatment systems.
