chemistry

Oil Red O

Oil Red O 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 Oil Red O rather than just read about it. In short: Oil Red O (Solvent Red 27, Sudan Red 5B, C.I. 26125, C26H24N4O) is a lysochrome (fat-soluble dye) diazo dye used for staining of neutral triglycerides and lipids on frozen sections and some lipoproteins on paraffin sections. It has the appearance of a red powder with an absorbance maximum at 518 nanometers.

Key takeaways

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

Reference excerpt

Oil Red O (Solvent Red 27, Sudan Red 5B, C.I. 26125, C26H24N4O) is a lysochrome (fat-soluble dye) diazo dye used for staining of neutral triglycerides and lipids on frozen sections and some lipoproteins on paraffin sections. It has the appearance of a red powder with an absorbance maximum at 518 nanometers.

Uses Oil Red O is one of the dyes used for Sudan staining. Similar dyes include Sudan III, Sudan IV, and Sudan Black B. The staining has to be performed on fresh samples, as alcohol fixation removes most lipids. Oil Red O largely replaced Sudan III and Sudan IV, as it provides much deeper red color and the stains are therefore much easier to see. Oil Red O can be used to mark lipid-containing vacuoles, particularly in cases of acute lymphoblastic leukemia or Burkitt's lymphoma. It can also be used to stain liver sections for histological analysis, quantify cell lipid content, and to stain the aorta to examine lesions from atherosclerosis. In pyrotechnics, Oil Red O is used in some compositions of red colored smokes.

Forensic When staining, Oil Red O can make fat more visible in various cuts in pathology. It is also used in a technique (the method is called as the dye: Oil Red O), discovered in 2004 by Alexandre Beaudoin, for staining latent fingerprints. This technique allows the development of latent fingerprints on porous exhibits (such as paper, cardboard, etc.) that are dry or wet. It mainly targets fat deposits on the surface of porous exhibits. It is a non-destructive technique (which does not destroy the exhibit nor prevents the use of other techniques). It is a safe alternative to the Physical Developer method, and is also used in sequence with other methods of fingerprints development.

References

External links Stains File entry [1]

Illustrations

Worked examples

Example 1 — a first encounter with Oil Red O

Start with the simplest possible case. Write down what Oil Red O 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 Oil Red O 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 Oil Red O 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 Oil Red O

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

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

Frequently asked questions

What is Oil Red O in simple terms?

Why does Oil Red O 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 Oil Red O?

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 Oil Red O.