Is Rhodamine B an amphoteric dye?

Yes, rhodamine B is an amphoteric dye. It has both positively and negatively charged groups on the molecule. However, it is usually listed as basic as it has an overall positive charge. Rhodamine B base is a colorless dye with undetectable fluorescence. In acidic conditions, rhodamine B base transforms into a colored rhodamine dye that acts as a stable and efficient laser dye. Rhodamine B is commonly used as a fluorescent dye to stain biological specimens.