• Prepare eosin Y stock solution. Add 2.0 g of water?soluble eosin Y to 40 mL of double?distilled H2O, and mix until dissolved. Then add 160 mL of 95% ethanol, and mix. Store at room temperature.
• Prepare eosin Y working solution. Add 200 mL of eosin Y stock solution to 600 mL of 80% ethanol and mix well. While working in a fume hood, add 4 mL of glacial acetic acid and mix well. Store covered at room temperature.