Erythrosine B (Erythrosine I) , a tetraiodofluorescein, is served as a red coloring in some foods (cherries, fish), as a disclosure of dental plaque, and as a stain of some cell types. Its structural was similar to thyroxine.

Instructions
I. Solution preparation
1. Mother solution preparation: Dissolve Erythrosine B in an appropriate solvent, such as anhydrous DMSO, ethanol or water, to prepare a stock solution of the required concentration.
The recommended concentration of the stock solution is 10-100 mM for subsequent dilution.
2. Working solution preparation: Dilute the mother solution into the working solution to be used according to the experimental purpose.
II. Operation steps
Cell staining
1. Culture the cells to an appropriate density.
2. Wash the cells with PBS and remove the culture medium.
3. Add the diluted Erythrosine B solution to the cells and incubate at 37°C in the dark for 15-30 minutes.
4. After incubation, wash the cells 3 times with PBS to remove unbound dye.
5. Fluorescence detection: Use a fluorescence microscope or flow cytometer for detection. The excitation wavelength of Erythrosine B is about 530 nm and the emission wavelength is about 550 nm.
Precautions:
1) Wear gloves during operation to avoid contact between skin or mucous membranes and reagents.
2) Avoid light exposure during incubation and storage to prevent fluorescence quenching.
3) After staining, fluorescence detection and analysis should be performed immediately.