Oil Red O, C.I. 26125, certified

Oil Red O, C.I. 26125, is a certified lysochrome azo dye used for histochemical visualization of neutral lipids. The dye partitions into hydrophobic lipid-rich regions and is commonly used to visualize triacylglycerol- and cholesteryl-ester-rich deposits in frozen tissue sections and cultured cells. It is also used as a post-electrophoresis stain for lipoproteins on cellulose acetate plates.

Synonyms: Solvent Red 27; Sudan Red 5B; Ceres Red 5B.

Key Properties

• Catalog number: 06317
• Colour Index number: C.I. 26125
• CAS Number: 1320-06-5
• Chemical class: Fat-soluble bis(azo) dye
• Grade: Certified biological stain
• Molecular formula: C26H24N4O
• Molecular weight: 408.5 g/mol
• Melting point: 120°C
• Storage: Room temperature
• Available sizes: 25 g and 100 g

Applications

Neutral Lipid Staining in Frozen Sections

Oil Red O is widely used to visualize neutral lipid deposits in frozen tissue sections. The stain is particularly associated with triacylglycerol- and cholesteryl-ester-rich lipid droplets.

Cell & Lipid Droplet Staining

Oil Red O is used in cultured-cell workflows to visualize intracellular neutral lipid accumulation, including studies of adipocyte differentiation and lipid storage.

Lipoprotein Electrophoresis

Oil Red O can be used as a post-electrophoresis stain for lipoproteins separated on cellulose acetate plates.

Staining & Method Considerations

• Frozen sections are generally preferred when the objective is preservation and visualization of extractable neutral lipids
• Staining intensity depends on specimen lipid content, working-solution composition, dye concentration, staining time, and washing or differentiation conditions
• Oil Red O working solutions are commonly prepared in alcohol-water systems and filtered before staining to minimize dye precipitate
• Aqueous mounting media are commonly used after Oil Red O staining of frozen sections
• For comparative studies, keep specimen preparation, section thickness, staining time, and imaging conditions consistent

Application Tips

• Use frozen sections when preservation of neutral lipid is important to the experimental endpoint
• Filter the working stain before use when required by the validated staining protocol
• Keep fixation, section thickness, stain exposure, and wash conditions consistent across experimental groups
• Use a lipid-positive control specimen or cell preparation when evaluating staining performance
• For image-based comparisons, use consistent microscope illumination, exposure, magnification, and analysis settings

Handling & Storage

• Store at room temperature with the container tightly closed
• Handle with good laboratory ventilation
• Avoid generating or inhaling dye dust during weighing and solution preparation
• Wear protective gloves and appropriate eye protection

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Safety & Documentation

Use appropriate laboratory ventilation and personal protective equipment when weighing or preparing Oil Red O solutions. Refer to the Safety Data Sheet (SDS) for complete handling, storage, and disposal information.