chemistry

Perfluorononanoic acid

Perfluorononanoic acid 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 Perfluorononanoic acid rather than just read about it. In short: Perfluorononanoic acid, or PFNA, is an organofluorine compound with the formula CF3(CF2)7CO2H. As the name implies it is the perfluorinated analogue of nonanoic acid, one of the perfluorinated carboxylic acids.

Key takeaways

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

Reference excerpt

Perfluorononanoic acid, or PFNA, is an organofluorine compound with the formula CF3(CF2)7CO2H. As the name implies it is the perfluorinated analogue of nonanoic acid, one of the perfluorinated carboxylic acids. As such, it is classified as a PFAS, a fluorosurfactant that has attracted attention as a persistent organic pollutant. Being a strong acid, perfluorononanoic acid does not exist in aqueous media. Instead, its conjugate base, perfluorononanoate is the active component. Most aspects attributed to perfluorononanoic acid are due to this anion.

Properties In the commercial product Surflon S-111 (CAS 72968-3-88), ammonium perfluorononanoate, is used as surfactant for the production of the fluoropolymer polyvinylidene fluoride. It is produced mainly in Japan by the oxidation of a linear fluorotelomer olefin mixture containing F(CF2)8CH=CH2. It can also be synthesized by the carboxylation of F(CF2)8I. PFNA can form from the biodegradation of 8:2 fluorotelomer alcohol. Additionally, it is considered a probable degradation product of many other compounds. PFNA is the largest perfluorinated carboxylic acid surfactant produced commercially. Fluorocarbon derivatives with terminal carboxylates are only surfactants when they possess five to nine carbons. Fluorosurfactants lower the surface tension of water down to half of what hydrocarbon surfactants can by concentrating at the liquid-air interface due to the lipophobicity of fluorocarbons. PFNA is very stable and is not known to degrade in the environment by oxidative processes because of the strength of the carbon–fluorine bond.

Environmental and health concerns Like the eight-carbon PFOA, the nine-carbon PFNA is a suspected developmental toxicant and an immune system toxicant. However, longer chain perfluorinated carboxylic acids (PFCAs) are considered more bioaccumulative and toxic. PFNA is an agonist of the nuclear receptors PPARα and PPARγ. In the years between 1999–2000 and 2003–2004, the geometric mean of PFNA increased from 0.5 parts per billion to 1.0 parts per billion in the US population's blood serum. and has also been found in human follicular fluid In a cross-sectional study of 2003–2004 US samples, a higher (13.9 milligram per deciliter) total cholesterol level was observed in when the highest quartile was compared to the lowest. Non-HDL cholesterol (or "bad cholesterol") levels were also higher in samples with more PFNA. In bottlenose dolphins from Delaware Bay, PFNA was the perfluorinated carboxylic acid measured in the highest concentration in blood plasma; it was found in concentrations well over 100 parts per billion. PFNA has been detected in polar bears in concentrations over 400 parts per billion. PFNA was the perfluorinated chemical measured in the highest concentration in Russian Baikal seals. However, PFOS is the perfluorinated compound that dominates in most wildlife biomonitoring samples.

Drinking water regulations In the United States, PFNA is currently regulated only at the state level. New Jersey became the first American state to set a standard for PFNA in September 2018, with a maximum contaminant level (MCL) of 13 ppt. This was soon followed by similar regulations for PFOA and PFOS. Other states such as Massachusetts, Rhode Island, and Vermont have MCLs for the sum of several PFAS that all include PFNA. In August 2020 the State of Michigan adopted drinking water standards for 5 previously unregulated PFAS compounds and lowered acceptable levels for 2 previously regulated compounds PFOS and PFOA to 16 ppt and 8 ppt respectively. PFNA has a MCL of 6 ppt. On April 10, 2024, the U.S. Environmental Protection Agency (EPA) announced the final National Primary Drinking Water Regulation (NPDWR) establishing Maximum Contaminant Levels (MCLs) for six PFAS including PFNA. However, in May, 2025, EPA announced changes that would rescind the regulations for PFNA, PFHxS, HFPO-DA (commonly known as GenX), and PFBS. The European Union regulates PFNA among a sum of many PFAS.

Food regulation In 2020, the European Food Safety Authority added PFNA in its revised safety threshold for PFAS that accumulate in the body. They set the threshold for a group of four PFAS of a tolerable weekly intake of 4.4 nanograms per kilogram of body weight per week.

Product restrictions In 2020, a California bill was passed banning PFNA as an intentionally added ingredient from cosmetics. In 2021, PFNA was restricted under REACH Regulation and in 2025, it was listed in Annex A of the Stockholm Convention on Persistent Organic Pollutants.

References

External links Perfluorocarboxylic Acid Content in 116 Articles of Commerce PDF Centers for Disease Control and Prevention, Polyfluorochemicals fact sheet Perfluorinated substances and their uses in Sweden Perfluoroalkylated substances, Aquatic environmental assessment Chain of Contamination: The Food Link, Perfluorinated Chemicals (PFCs) Incl. PFOS & PFOA

Illustrations

Worked examples

Example 1 — a first encounter with Perfluorononanoic acid

Start with the simplest possible case. Write down what Perfluorononanoic acid 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 Perfluorononanoic acid 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 Perfluorononanoic acid 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 Perfluorononanoic acid

In research: Perfluorononanoic acid 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 Perfluorononanoic acid 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: Perfluorononanoic acid is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anionic surfactants, PBT substances, Perfluorocarboxylic acids, so understanding it makes those chapters shorter.
In everyday life: Look for Perfluorononanoic acid 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 Perfluorononanoic acid in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Perfluorononanoic acid 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 Perfluorononanoic acid out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Perfluorononanoic acid in simple terms?

Why does Perfluorononanoic acid 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 Perfluorononanoic acid?

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 Perfluorononanoic acid.