Eosin Y, C.I. 45380, is the disodium salt of tetrabromofluorescein, an anionic xanthene dye used as a cytoplasmic counterstain. In hematoxylin and eosin (H&E) staining, eosin produces pink to red cytoplasmic coloration that contrasts with blue nuclear staining.
The dye is also a component of Wright stain and MacNeal’s Tetrachrome stain. These multicomponent formulations combine eosin with other dyes to produce differential staining.
This solid dye powder is used to prepare staining solutions according to the selected method. Solution composition, staining time, and subsequent washing and dehydration steps should be controlled for the specimen and staining procedure.
Key Properties
- Product number: 02740
- CAS number: 17372-87-1
- Molecular formula: C20H6Br4Na2O5
- Molecular weight: 691.9g/mol
- Physical form: Solid powder
- Chemical class: Anionic xanthene dye; tetrabromofluorescein disodium salt
- Colour Index number: C.I. 45380
- Synonyms: Eosin yellowish; Acid Red 87; Eosin Y disodium salt
Applications
Hematoxylin & Eosin Counterstaining
Eosin Y is used as the cytoplasmic counterstain in H&E procedures. Its pink to red coloration provides contrast with hematoxylin-stained nuclei for microscopic examination of tissue morphology.
Wright Stain Preparation
Eosin Y is a component of Wright stain formulations. Preparing a complete Wright stain requires the other dye components and method-specific preparation conditions; eosin powder alone does not reproduce the combined stain. For the complete dye preparation, see Wright stain powder.
MacNeal’s Tetrachrome Stain Preparation
Eosin Y is a component of MacNeal’s Tetrachrome stain, a multicomponent stain used for blood films and bone sections. For the complete stain preparation, see MacNeal’s Tetrachrome stain.
Staining & Formulation Considerations
- Prepare the powder using the solution composition specified by the selected staining method
- Control dye concentration and staining time rather than applying one set of conditions to every specimen
- For paraffin sections, follow the method’s deparaffinization and rehydration steps before staining
- Subsequent alcohol steps can remove excess eosin and should be controlled when assessing staining intensity
- Use the complete dye formulation when preparing Wright or MacNeal’s Tetrachrome stains
Storage & Product Selection
- Store the solid dye at room temperature in a secure, well-ventilated location
- Package size: 50g
- Package catalog number: 02740-50
- Solid dye powder; use protective gloves, safety glasses, protective clothing, and appropriate ventilation when handling
- Download the Eosin Y Safety Data Sheet for catalog 02740
- For larger quantities, request a bulk quote and specify Eosin Y, C.I. 45380, catalog 02740
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FAQ
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1. What is Eosin Y used for?
Eosin Y is used for cytoplasmic counterstaining, including hematoxylin and eosin staining. It is also a dye component in Wright stain and MacNeal’s Tetrachrome stain formulations.
2. What does C.I. 45380 mean?
C.I. 45380 is the Colour Index number associated with Eosin Y, also known as Acid Red 87 or eosin yellowish. This product is the disodium salt.
3. What color does Eosin Y produce in H&E staining?
Eosin Y produces pink to red cytoplasmic staining. Hematoxylin provides the contrasting blue nuclear stain. The final appearance depends on the staining formulation and processing conditions.
4. What are the molecular weight and CAS number of Eosin Y disodium salt?
Eosin Y disodium salt has a molecular weight of approximately 691.9g/mol, the molecular formula C20H6Br4Na2O5, and CAS number 17372-87-1.
5. How should Eosin Y powder be stored?
Store the solid dye at room temperature in a secure, well-ventilated location. Follow the SDS for handling and storage. Prepared staining solutions require storage conditions appropriate to their formulation.
6. Is this Eosin Y a powder or a prepared staining solution?
This is solid Eosin Y dye powder for preparing staining solutions. The 50g package is catalog 02740-50. It is not a ready-to-use staining solution or a complete multicomponent stain.
7. Where can I obtain the Eosin Y SDS?
Download the Eosin Y Safety Data Sheet for catalog 02740.
