NP-40 (also known as Tergitol-type NP-40 and nonyl phenoxypolyethoxylethanol[1]) is a commercially available detergent with CAS Registry Number 9016-45-9. NP-40 is an ethoxylated nonylphenol for non-ionic surfactants and can act as emulsifier and demulsifier agent.
NP-40 has applications in paper and textile processing, in paints and coatings, and in agrochemical manufacturing.
Care should be taken to avoid confusing NP-40 with Nonidet P-40 (octyl phenoxypolyethoxylethanol) which is currently out of production. Nonidet P-40 ("Non-Ionic Detergent") was originally manufactured and trademarked by the Shell Chemical Company,[2] but was phased out of production in the early 2000s. Confusingly, biochemical protocols published between the 1960s[3] and 2000s refer to Shell's Nonidet P-40 as NP-40. Shell's original Nonidet P-40 had a hydrophilic-lipophilic balance (HLB) value of 13.5,[4] as opposed to 12.9 for the currently available IGEPAL CA-630,[5] indicating that the currently available compound is more potent than the compound used in older publications. Indeed, according to a 2017 report,[6] an additional dilution factor of 10 was required for the currently available NP-40 ("Nonidet P-40 substitutes") to match the activity of the previously available, and now discontinued, Shell's Nonidet P-40.
