Oil Red O



Cas number: 1320-06-5
Shelf life: 60 months
H.S. Code: 3204.9000
Molecular Weight: 408.49
Alternate Names: Solvent Red 27, C.I. 26125

Oil Red O is a lysochrome (fat-soluble dye) predominantly used in histology for staining neutral triglycerides and lipids in tissues, marking it as a valuable tool in the study of fat metabolism and storage within cells.

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Oil Red O or Solvent Red 27 is used to stain lipids and fat. It can also be used as a lysochrome diazo dye for staining neutral triglycerides and lipids on frozen sections, and some lipoproteins on paraffin sections.

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.

Oil Red O 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.

Kit Contents

  • VB-3007-1 Pre-Stain Solution ———————– 100 ml
  • VB-3007-2 Oil Red O Solution ————————100 ml
  • VB-3007-3 Differentiation Solution————— 100 ml
  • VB-3007-4 Mayer’s Hematoxylin Solution —- 100 ml


Room temperature.


  1. Cut frozen sections to 8 to10μm. Air dry the sections to the slides
  2. Fix in 10% buffered formalin for 20 mins at room temperature, briefly wash with running tap water for 3 mins.
  3. Place in Pre-Stain Solution for 2 mins
  4. Stain in pre-warmed Oil Red O solution for 10 minutes at room temperature
  5. Differentiate in Differentiation Solution for 5 minutes at room temperature
  6. Rinse in 2 water changes of distilled at room temperature.
  7. Lightly stain nuclei with Mayer’s Hematoxylin Solution for 1 minute.
  8. Rinse with tap water for 3 mins
  9. Mount with aqueous mounting medium.

Solvent Red 27 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.

Sudan Red 5B Properties

Cas number: …………….. 1320-06-5
Chemical formula: ……. C26H24N4O
Molar mass: …………….. 408.49496
ChEBI: CHEBI:   88213
ChemSpider:   14217961
ECHA InfoCard: 100.013.906
MeSH: oil+red+O
PubChem CID: 5841742
CompTox Dashboard (EPA)


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