Oil Red O (Solvent Red 27, Sudan Red 5B, C.I. 26125, C₂₆H₂₄N₄O) is a

lysochrome A lysochrome is a soluble dye used for histochemical staining of lipids, which include triglycerides, fatty acids, and lipoprotein A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as ...

(fat-soluble dye) diazo dye used for staining of neutral

triglycerides A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and ''glyceride''). Triglycerides are the main constituents of body fat in humans and other vertebrates, as we ...

and

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...

s on frozen sections and some

lipoproteins A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, su ...

on paraffin sections. It has the appearance of a red powder with an absorbance maxima at 518 nanometers.

Uses

Oil Red O is one of the dyes used for

Sudan stain Sudan ( or ; ar, السودان, as-Sūdān, officially the Republic of the Sudan ( ar, جمهورية السودان, link=no, Jumhūriyyat as-Sūdān), is a country in Northeast Africa. It shares borders with the Central African Republic t ...

ing. Similar dyes include Sudan III,

Sudan IV Sudan IV (C24H20N4O) is a lysochrome (fat-soluble dye) diazo dye used for the staining of lipids, triglycerides and lipoproteins on frozen paraffin sections. It has the appearance of reddish brown crystals with melting point 199 °C and m ...

, 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. In pyrotechnics, Oil Red O is used in some compositions of red

colored smoke Colored smoke is a kind of smoke created by an aerosol of small particles of a suitable pigment or dye. Colored smoke can be used for smoke signals, often in a military context. It can be produced by smoke grenades, or by various other pyrote ...

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

fingerprint A fingerprint is an impression left by the friction ridges of a human finger. The recovery of partial fingerprints from a crime scene is an important method of forensic science. Moisture and grease on a finger result in fingerprints on surfac ...

s. 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 and doesn’t prevent 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.Guigui, K.; Beaudoin, A. The use of Oil Red O in sequence with other methods of fingerprint development. Journal of Forensic Identification, 2007, 57 (4), 550-581.

References

External links

Stains File
entry {{Stains Azo dyes Forensic chemicals Staining dyes Sudan dyes 2-Naphthols