Sunday, November 23, 2008

seein' fluoroscein

The other day it came up that the dye making Mountain Dew yellow might be one and the same as the stuff that is used to color antifreeze. Seemed possible to me. I just happened to be familiar with this particular compound, called fluorescein, since I used it in grad school as a fluorescent tag on some molecules I was interested in.

As usual I searched Wikipedia, and I found a nice article about fluorescein. And according to my completely unverifiable web research, Mountain Dew is dyed with yellow number 5, and fluorescein dyes include yellow numbers 7 and 8.

The list of uses Wikipedia has for fluorescein is pretty amazing, though. In addition to its use as a dye and as a flluorescent chemical marker, it is also used in forensics to detect latent blood stains, in hydrology (dump it in at point A and look for it at point B, where you think the water flows), and medically to detect problems in the eyes and vascular system.

As to its use as a colorant in auto radiator fluid, I found an article posted on MedLine that suggests this was at least true in 1990, when the article was published. The gist of the article is that when given a dose of fluorescein similar to that which one would get from ingesting a toxic amount of antifreeze, men passed enough fluorescein in their urine that it could be detected with something called a Wood's lamp, which must be a uv lamp.

That's pretty weird but I think it's also pretty cool!

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