chemistry

Ponceau 4R

Ponceau 4R 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 Ponceau 4R rather than just read about it. In short: Ponceau 4R (known by more than 100 synonyms, including as C.I. 16255, cochineal red A, C.I. acid red 18, brilliant scarlet 3R, brilliant scarlet 4R, new coccine,) is a synthetic colourant that may be used as a food colouring. It is denoted by E Number E124.

Key takeaways

Ponceau 4R belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ponceau 4R to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ponceau 4R from memory before moving on to harder problems.

Reference excerpt

Ponceau 4R (known by more than 100 synonyms, including as C.I. 16255, cochineal red A, C.I. acid red 18, brilliant scarlet 3R, brilliant scarlet 4R, new coccine,) is a synthetic colourant that may be used as a food colouring. It is denoted by E Number E124. Its chemical name is 1-(4-sulfo-1-napthylazo)-2-napthol-6,8-disulfonic acid, trisodium salt. Ponceau (17th century French for "poppy-coloured") is the generic name for a family of azo dyes. Ponceau 4R is a strawberry red azo dye which can be used in a variety of food products, and is usually synthesized from aromatic hydrocarbons; it is stable to light, heat, and acid but fades in the presence of ascorbic acid. It is used in Europe, Asia, and Australia, but has not been approved for human consumption by the United States Food and Drug Administration.

Health effects There is no evidence of carcinogenicity, genotoxicity, neurotoxicity, or reproductive and developmental toxicity at the permitted dietary exposures; the European acceptable daily intake (ADI) is 0.7 mg/kg and the WHO/FAO ADI is 4 mg/kg. The production process may result in unsulfonated aromatic amines present in concentrations of up to 100 mg/kg which may be linked to cancer. The lake pigment form of the colour additive can also increase the intake of aluminium beyond the tolerable weekly intake (TWI) of 1 mg/kg/week. Therefore, the limit for aluminium may be adjusted to accommodate for this.

Possible cause of hyperactivity Since the 1970s and the well-publicized advocacy of Benjamin Feingold, there has been public concern that food colourings may cause ADHD-like behavior in children. These concerns have led the FDA and other food safety authorities to regularly review the scientific literature, and led the UK FSA to commission a study by researchers at Southampton University of the effect of a mixture of six food dyes (tartrazine, Allura Red AC, ponceau 4R, Quinoline Yellow WS, sunset yellow and carmoisine, dubbed the "Southampton 6") and sodium benzoate (a preservative) on children in the general population, who consumed them in beverages; the study published in 2007. The study found "a possible link between the consumption of these artificial colours and a sodium benzoate preservative and increased hyperactivity" in the children; the advisory committee to the FSA that evaluated the study also determined that because of study limitations, the results could not be extrapolated to the general population, and further testing was recommended. The European regulatory community, with a stronger emphasis on the precautionary principle, required labelling and temporarily reduced the acceptable daily intake (ADI) for the food colourings; the UK FSA called for voluntary withdrawal of the colourings by food manufacturers. However, in 2009 the EFSA re-evaluated the data at hand and determined that "the available scientific evidence does not substantiate a link between the colour additives and behavioural effects". There is no evidence to support broad claims that food colouring causes food intolerance and ADHD-like behaviour in children. It is possible that certain food colouring may act as a trigger in those who are genetically predisposed, but the evidence is weak.

References

External links Carcinogenic Potency Database Project entry for SX purple, alias Ponceau 4R Some more details, other common names

Illustrations

Worked examples

Example 1 — a first encounter with Ponceau 4R

Start with the simplest possible case. Write down what Ponceau 4R 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 Ponceau 4R 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 Ponceau 4R 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 Ponceau 4R

In research: Ponceau 4R 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 Ponceau 4R 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: Ponceau 4R is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2-Naphthols, Acid dyes, Azo dyes, so understanding it makes those chapters shorter.
In everyday life: Look for Ponceau 4R 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 Ponceau 4R in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ponceau 4R 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 Ponceau 4R out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ponceau 4R in simple terms?

Why does Ponceau 4R 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 Ponceau 4R?

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 Ponceau 4R.