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

I worked with someone who used to try to sneak fluorescein into peoples drinks, or at least claimed to.

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!