O0625 Sigma-Aldrich

Oil Red O

certified by the Biological Stain Commission

Synonym: 1-([4-(Xylylazo)xylyl]azo)-2-naphthol, 1-[2,5-Dimethyl-4-(2,5-dimethylphenylazo)phenylazo]-2-naphthol, Solvent Red 27

  • CAS Number 1320-06-5

  • Empirical Formula (Hill Notation) C26H24N4O

  • Molecular Weight 408.49

  •  Colour Index Number 26125

  •  EC Number 215-295-3

  •  MDL number MFCD00003898

  •  PubChem Substance ID 24897931



Related Categories Cell Biology, Certified Stains & Dyes, Hematology and Histology, O, Stains & Dyes, A to Z,
grade   certified by the Biological Stain Commission
form   powder
composition   Dye content, ≥75%
mp   120 °C (dec.) (lit.)
solubility   chloroform/ethanol (1:1): 1 mg/mL


General description

Oil Red O is a lysochrome. It is used to stain and visualise general localization of fats.

Oil Red O stains lipid materials and the lipids take red-orange color. It also marks vacuoles, particularly observed in ALL-L3 (acute lymphoblastic leukemia) or Burkitt’s lymphoma/leukemia. Oil Red O staining is done on fresh samples, since alcohol fixation removes lipid.


Oil Red O has been used for the staining of lipid droplets and lipid-containing vacuoles in cells.

Oil Red O has been used:
• for staining liver sections in histological analysis
• for the quantification of lipids in cells
• to stain aorta to examine atherosclerotic lesions


25, 100 g in glass bottle


Certified for use as a fat stain in Churukian′s modification of the method of Lillie and Asburn.

Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 


Certificate of Analysis


Certificate of Origin


Frequently Asked Questions

Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
What is the basic principle involved in the staining of fats and lipids with Oil Red O, Product O0625?
The Oil Red O is only minimally soluble in the solvent.Solubility is typically decreased by diluting the stock Oil Red O solutions in water before use.The Oil Red O then moves from the solution to the lipid - where there is greater solubility.
Is there a recommended staining procedure for Product O0625, Oil Red O, for staining fats or lipids in tissue sections.
Yes, there are several.Working solutions prepared without dextrin typically have shorter stability dating.The method of the Biological Stain Commission is listed in: Penny, DP et al, Analysis and testing of biological stains - The Biological Stain Commission Procedures. Biotech. Histochem. 77(5&6), 237-275, (2002).The Churukian method is also listed in Bancroft, J and Gamble, M; Theory and Practice of Histological Techniques, Churchill Livingstone, New York 2002 pages 207-208.
Can the Oil Red O, Product O0625,staining procedure be used with paraffin sections of tissue?
No.The solvents typically used in paraffin processing will dissolve away most of the fats and lipids.Frozen sections are the preferred tissue specimen.
Can Oil Red O, Product O0625,be utilized for staining adipocytes in cell culture?
Yes, although the cultured cells must first be fixed before staining.Preferred fixatives would include aqueous fixatives such as 10% neutral buffered formalin.Avoid fixatives such as ethanol or acetone. After fixation and rinsing, the cells may be stained with the basic procedures used for staining tissues attached to glass slides
Has product O0625, Oil Red O,been use-tested for staining lipoproteins in agarose gels?
Each lot of Product O0625 has been certified for use in histological applications by the Biological Stain Commission.It is not specifically use-tested for any electrophoresis application.We offer a different grade of Oil Red O (Product No. O9755) which has been tested for suitability in electrophoresis; each lot of O9755 has been tested and found suitable for staining lipoproteins that have been separated by cellulose acetate electrophoresis.
How do I find price and availability?
There are several ways to find pricing and availability for our products.Once you log onto our website, you will find the price and availability displayed on the product detail page.You can contact any of our Customer Sales and Service offices to receive a quote. USA customers: 1-800-325-3010 orview local office numbers.
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
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