I normally wash my phosphate and TCAA buffers with dichloromethane (DCM). For the first time, yesterday, I added 10% DCM to the phosphate buffer as usual and a weird thing happened. The DCM turned purplish-pink. It did settle out at the bottom of the bottle but maintained this strange coloration even after an hour. The buffer solution itself was clear and clean. Has anyone experienced this before? What could be behind this observation?
Hello Chika,
many thanks for sharing this very interesting and unusual chemical problem with the RG community. Sorry to see that your question has not yet received an expert answer. My only explanation would be that you perhaps had some iodide ions (iodide salts) in your mixture. When iodide salts are oxidized, e.g. by oxygen in the air or other oxidizing agents, elemental iodine (I2) can be formed which is soluble in DCM with a purple or purplish-pink color (depending on the concentration. Elemental iodine is insoluble in water and goes into the DCM phase.
Goos luck with your work and best wishes, Frank Edelmann
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