Nonidet

Nonidet is a trade name used for a family of nonionic surfactants derived from nonylphenol ethoxylates. The most widely known product is Nonidet P-40 (NP-40), a viscous, colorless liquid used as a detergent and membrane-permeabilizing agent in laboratory settings. Nonidet materials are not a single chemical but mixtures of nonylphenol polyethoxylates, with the exact composition depending on the supplier. They are characterized by a polyethoxylate chain attached to a nonylphenol group, which gives them detergent and solubilizing properties.

Uses for NP-40 include helping to lyse cells and solubilize membrane proteins in biochemical and molecular biology workflows. It is commonly employed in cell lysis buffers, protein extraction protocols, and various immunological techniques such as immunoprecipitation. Because it is milder than some ionic detergents, NP-40 is often chosen when preserving protein activity and structure is important, though its effectiveness depends on the application.

Safety and handling guidelines describe NP-40 as a skin and eye irritant. Users should wear appropriate protective equipment, work in a well-ventilated area, and follow local disposal regulations. It should be kept away from incompatible materials and disposed of according to institutional and regional guidelines.

Environmental and regulatory notes highlight concerns about nonylphenol ethoxylates, which can degrade to nonylphenol, a compound with persistent, estrogenic activity that can affect aquatic life. As a result, some regions regulate or encourage substitution with alternative detergents, leading to broader adoption of NP-40–free protocols or alternatives in certain applications.