Fluorescein: What makes the Chicago River green?

Edit: Looks like I might be off on this.

CNN has a clip in the rotation right now about the yearly tradition of dying the Chicago river green for St. Patrick's day. They're saying it's a "secret orange dye." Well, let me put it through the decomplicator for you.

i-d081dec9720c079d7024ee24c6a40292-fluorescein.gif

As you might remember from last year, it's fluorescein. That is all. Happy St. Patrick's day.

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@Sarah
Believe me, it's Fluorescein. Do you really think they would have to keep it a secret otherwise?
I read about food coloring all the time; Yeah right, have you ever eaten anything that lights up under a blacklight?
Red/brown powder turning fluorescent green in water = Fluorescein
If a similar substance would exist we would know about it :)

Are you sure it's not leprechauns?

The river looks green without the dye...Just sayin'.

By Chi-town gnome (not verified) on 16 Mar 2008 #permalink

Impure sodium fluorescein is "uranine" (C.I. Acid Yellow 73). As with phenolphthalein, impurities in low grade stuff can cause enhanced lower gastrointestinal motility. How could anybody knowingly ingest a sufficient slug of the stuff?

Abs(max) = 490 nm
Emis(max) = 514 nm
Isoabs = 460 nm (vs. pH)

One imagines select Plumbers Union members had some very moving moments after their sloppy dispersal of powdered solids - no face masks.

I don't think anyone should be dumping secret chemicals in ANY
body of water. The potential for harm is too great. Is it a secret so the EPA can't ban it? This is a situation where the
public and regulatory agencies have a right to know. Reveal the secret or STOP DUMPING CHEMICALS IN THE WATER!