[kimmetyvv]

{MOD Edit -- split off posting}
I hope you still see this, since you've posted this a long time ago.
I'm doing my thesis about blood detection, and one of the subjects is fluorescein..
But you talk about fluorescin, my question is in which ways this differs from fluorescein, because I cannot find anything about it.
So maybe you could give me the chemical structure of both substances (:

thanks 

[Arkcon]

Welcome to the forums, we like to help students understand problems for themselves, so they learn to get good results.  For this question, we have much to do:

Try to spell fluorescein properly at all times.  A slight mis-spelling could be the name of a different product.  If you want to know about one, don't ask about another. You seem to be asking about one or the other, but that may simply be a mis-spelling, or an archaic spelling.  Or British English vs American English.  When confronted by a problem such as this one, what you need is context -- what else do you know about fluorescin/fluorescein?  Where did you hear about them?  What papers will you quote?  I really doubt you got a thesis assignment, on a piece of folded paper, with the word: fluorescin on it, and the verbal instruction: Go.

[Yggdrasil]

I am a graduate student who does fluorescence spectroscopy and I have not heard of any dye called fluorescin.  Unless you can point to any papers that reference fluorescin specifically, my guess is that it is just a misspelling of the dye fluorescein, which is commonly used in biology.

[Babcock_Hall]

Fluorescin, CAS registry number [518-44-5], is more reduced than fluorescein, CAS registry number [2321-07-5].  It's a little bit like phenolphthlein versus phenolphthalin.  The latter is more reduced than the former, and it is used in the Kastle-Meyer test.  Is your application in the area of forensics by any chance?  Are you looking at the pseudoperoxidase reaction catalyzed by hemoglobin?

[Babcock_Hall]

Here is a link to a patent that describes fluorescin:
http://www.google.com/patents/US6692967
Here is a paper that discusses reduced fluorescein in detection of blood:
http://library-resources.cqu.edu.au/JFS/PDF/vol_45/iss_5/JFS4551090.pdf

Fluorescin is less highly conjugated than fluorescein is.  I am not sure whether or not it is even fluorescent.

[cyb0rg]

{MOD Edit -- split off posting}
I hope you still see this, since you've posted this a long time ago.
I'm doing my thesis about blood detection, and one of the subjects is fluorescein..
But you talk about fluorescin, my question is in which ways this differs from fluorescein, because I cannot find anything about it.
So maybe you could give me the chemical structure of both substances (:

thanks 

see cerfull this 2 structures and u will see a difeence 

http://www.vvchem.com/cas-518/518-44-5.html

http://en.wikipedia.org/wiki/Fluorescein

Fluorescein in right benzen ring has =O chinon and fluorescin has -OH if u need more info ill help you.