chemistry

NP-40

NP-40 is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand NP-40 rather than just read about it. In short: NP-40 (also known as Tergitol-type NP-40 and nonyl phenoxypolyethoxylethanol) 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.

Key takeaways

NP-40 belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NP-40 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NP-40 from memory before moving on to harder problems.

Reference excerpt

NP-40 (also known as Tergitol-type NP-40 and nonyl phenoxypolyethoxylethanol) 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 is often used to break open all membranes within a cell, including the nuclear membrane . To break only the cytoplasmic membrane, other detergents such as digitonin can be used. 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, but was phased out of production in the early 2000s. Confusingly, biochemical protocols published between the 1960s 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, as opposed to 12.9 for the currently available IGEPAL CA-630, indicating that the currently available compound is more potent than the compound used in older publications. Indeed, according to a 2017 report, 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.

See also Nonoxynol-9 Surfactant Lipid bilayer Detergent Triton X-100 (differs only in the # of carbons in the aliphatic portion)

References

Illustrations

Worked examples

Example 1 — a first encounter with NP-40

Start with the simplest possible case. Write down what NP-40 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to NP-40 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about NP-40 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of NP-40

In research: NP-40 appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses NP-40 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: NP-40 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Biochemistry methods, Non-ionic surfactants, so understanding it makes those chapters shorter.
In everyday life: Look for NP-40 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study NP-40 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NP-40 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain NP-40 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NP-40 in simple terms?

Why does NP-40 matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study NP-40?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on NP-40.