Nonidet P-40 is a nonionic, non-denaturing detergent

Detergent

A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...

. Its official IUPAC name is octylphenoxypolyethoxyethanol. Nonidet is a trademark of Shell Chemical Co.

Shell Chemicals

Shell Chemicals is the petrochemicals arm of Royal Dutch Shell. The name "Shell Chemicals" refers to the nearly seventy companies engaged in chemicals businesses for Shell, which together make up one of the largest petrochemical producers in the world....

Nonidet P-40 is sometimes abbreviated as NP-40, but should not be confused with a different detergent by the same name (NP-40

NP-40

NP-40 is a commercially available detergent. The full name of NP-40 is Tergitol-type NP-40, which is nonyl phenoxypolyethoxylethanol.Care should be taken to avoid confusing NP-40 with Nonidet P-40 ....

, nonylphenoxypolyethoxyethanol).

Nonidet P-40 is no longer sold by the chemical company Sigma-Aldrich

Sigma-Aldrich

Sigma-Aldrich Corporation , is a life science and high technology company with over 7,600 employees and operations in 40 countries. Its chemical and biochemical products and kits are used in scientific research, biotechnology, pharmaceutical development, the diagnosis of disease, and as key...

. Sigma-Aldrich has replaced Nonidet P-40 with IGEPAL CA-630

IGEPAL CA-630

IGEPAL CA-630 is a nonionic, non-denaturing detergent. Its official IUPAC name is octylphenoxypolyethoxyethanol. IGEPAL is a registered trademark of Rhodia....

, which is described as a "nonionic, non-denaturing detergent". Sigma-Aldrich claims that IGEPAL CA-630 is "chemically indistinguishable from Nonidet P-40".