Sciencemadness Discussion Board

Fluorescein

encipher - 6-1-2007 at 16:11

Hi,


Does anyone know where is a good source of acquiring Fluorescein. I have checked my usual chemical suppliers, and also looked up the synthesis (which is too advanced for me). Any ideas on the availability of it here in the United States?
I have however found the following on ebay:
http://cgi.ebay.com/Fluorescein-sodium-Indicator-Reagent-100...

It is Flouroscein sodium salt. My use of flouroscein will be for the visual aspect only (its flourescence). Is that salt also suitable?

Also, if anyone knows another compound with a similar effect, please mention it.


Thanks

[Edited on 1-7-2007 by encipher]

Sauron - 6-1-2007 at 16:42

Fluorscein is easy to make.

You need phthalic anhydride and resorcinol. You need either concentrated H2SO4 (but only a little but) or anhydrous zinc chloride as catalyst. The procedure is in Vogel's book (Practical Organic Chemistry 3rd.Ed.) which you can download freely from the forum library.

Fluorscein is a FD&C color. (Food, Drug & Cosmetics) I think it is FD&C Yellow but I frget which number it is. I believe it is the sodium salt you want. It fluoresces in solution even whenvery dilute. They use it to trace the course of underground rivers and streams.

garage chemist - 6-1-2007 at 18:00

Fluorescein itself does not fluorescence, its only the sodium salt that does. So you want the sodium salt.

And the synthesis of fluorescein is not advanced at all. Also the chemicals for it are cheap.

Sauron - 6-1-2007 at 18:25

Quite right. I did it when I was a young teenager, only not very efficiently because I did not comprehend the need for a Lewis acid catalyst to "condense" the two mols of resorcinol with one mol of phthalic anhydride.

Don't let the odd names throw you either. Resorcinol is just 1,3 dihydroxybenzene (or 3-hydroxyphenol if you prefer).

And phthalic anhydride is 1,2-benzenedicarboxylic anhydride.

They are cheap because they are vast importance industrially and thus, mass produced.

encipher - 6-1-2007 at 18:38

Quote:
Originally posted by garage chemist
Fluorescein itself does not fluorescence, its only the sodium salt that does. So you want the sodium salt.

And the synthesis of fluorescein is not advanced at all. Also the chemicals for it are cheap.


Yes, but I do not have any of the chemicals required to synthesize it, so I would end up having to make those etc.. which is why I said it would be too advanced. Organic isn't exactly my strong point either.

But thanks, I guess I'll be getting the sodium salt then.

Also, would you happen to know of any other flourescent compounds that are low in toxicity?

Thanks again.

Sauron - 6-1-2007 at 19:36

Ever see "Ra-Animator"? Remember the green-yellow glowing, radioactive looking liquid in the syringes? THAT is sodium salt of fluorscein. Just remember a little goes a LONG way.

Ever have corneal abrasion? Or otherwise have an eye exam requiring the slit lamp? If so remember the orange strip of paper that the doctor or nurse just touched to your eye? THAT was sodium fluorscein. and that's why there's a UV lamp in that instrunebt,

Nicodem - 7-1-2007 at 04:16

I remember a medicine containing fluoroscein that I used years ago to cure some fish disease in my aquarium. I don't remember what the disease was but I guess it is only added as a color marker (it makes the aquarium water glow green). So, if you only need a little to color something you might check an aquarium store.

matei - 7-1-2007 at 06:21

Quote:
Originally posted by encipher
Also, would you happen to know of any other flourescent compounds that are low in toxicity?


Rhodamine B has a very nice magenta (or pink in very dilute solutions) fluorescence. However it is rated R: 22-41, which means "Harmful if swallowed" and "Toxic in contact with skin".

YT2095 - 7-1-2007 at 09:19

I believe Quinine is another compound that`s non toxic in small amounts and will fluoresce under UV.

just out of curiosity, is there any way to break fluorescein down into anything useful, I have about 90g of the free acid, More than enough for several lifetimes of green glowy stuff!

Nick F - 7-1-2007 at 11:00

Yeah, quinine does. Ever noticed that your gin and tonic glows slightly blue in summer sunshine? Or REALLY blue under UV in a club?

YT2095 - 7-1-2007 at 11:25

that`s the one :))

I just realised, if you`re the Encipher I know, then I`ll send you some Fluorescein if you like, it`s the Acid itself, easy enough to convert to the sodium salt if you wanted to :)

woelen - 7-1-2007 at 13:53

YT2095, I found this reaction, making eosin from fluorescein. It might be an interesting experiment for you.

http://www.versuchschemie.de/topic,4881,-Eosin+aus+Fluoresce...

It is in German, but you should be able to grasp the idea behind it.

YT2095 - 9-1-2007 at 05:52

Interesting!
I didn`t wish to mess about with Bromine today, so I made Erythrosin instead :)
it`s the same synth more or less, just use Iodine instead of Bromine.

maybe when I`m feeling a little better, I`ll try the other Halogens too.

YT2095 - 12-1-2007 at 02:30

I just did the Eosin synth, this stuff is Insane!:o
diluted to 62500:1 and it`s still pink visible, it stains everything it touches with any sort of porous surface incl the sink, and I havent worked out how to shift it yet, neat bleach doesn`t touch it (NaOCl 5%).
I`ve dyed a wool swatch, and it`s now Acid Pink, so I`m really pleased with it as a dye, I just need to figure a way to destroy it now.
also NaOH doesn`t change the color either, I thought it might alter it.

EDIT: Update, Chlorox Bleach, WILL attack it, it just takes a while *phew*

[Edited on 12-1-2007 by YT2095]

re: fluorescein suppliers

anti_vizsla - 26-1-2007 at 04:28

Fluorescein is fairly cheap.
Try to get it from Molecular Probes (www.probes.com)

As for using other compounds with similar emission...stick with fluorescein, its fluorescence quantum yield is 0.9.
From my research experience, its the best green emitting organic fluorophore.

N.B. For emission don't use a concentration higher that 10^(-5) M, it will form H-type aggregates which lead to self-quenching.
Carefull, with the pH value used, its also pH sensitive.

aludel - 6-2-2007 at 15:19

I got 10 grams of fluorescein recently, it's a reddish-brown powder, not at all fluorescent. After dissolving a bit in a weak NaOH solution a bright green glow appears under a blacklight: the sodium salt!

I'm going to try to make fluorescent paint from this (being a painter), the solution itself isn't suitable to paint with. Somehow attach it to an insoluble carrier to get a pigment rather than a dye...

py3rhcl3 - 13-2-2007 at 01:01

Quote:
Originally posted by aludel
After dissolving a bit in a weak NaOH solution a bright green glow appears under a blacklight: the sodium salt!


To be exact, the onset of the fluorescence of fluorescein in basic media isn't caused by the formation of the sodium salt, rather than by the deprotonation of one of the hydroxygroups on the ring. Also the non-fluorescent lacton-form isn't stable in alkaline media.
Quote:
Originally posted by aludel
I'm going to try to make fluorescent paint from this (being a painter), the solution itself isn't suitable to paint with. Somehow attach it to an insoluble carrier to get a pigment rather than a dye...


The problem is that esp. fluorescein is _very_ photolabile and therefore would bleach extremly fast under constant irradiation (daylight). You have to use a photostable fluorophor when using it as paint....

joeflsts - 13-3-2007 at 18:28

Quote:
Originally posted by YT2095
I just did the Eosin synth, this stuff is Insane!:o
diluted to 62500:1 and it`s still pink visible, it stains everything it touches with any sort of porous surface incl the sink, and I havent worked out how to shift it yet, neat bleach doesn`t touch it (NaOCl 5%).
I`ve dyed a wool swatch, and it`s now Acid Pink, so I`m really pleased with it as a dye, I just need to figure a way to destroy it now.
also NaOH doesn`t change the color either, I thought it might alter it.

EDIT: Update, Chlorox Bleach, WILL attack it, it just takes a while *phew*

[Edited on 12-1-2007 by YT2095]


YT - In what form did you use Bromine? Did you use it as bromine water or as liquid bromine?

I just complete making fluorescein and I'm now interested in attempting Eosin. I had to laugh at your comments regarding cleanup. While cleaning up the fluorescein I used 10% Ammonia and damn near gassed myself! :o

Joe

YT2095 - 14-3-2007 at 01:16

I had liquid bromine under a little water, I worked small scale and only had 0.5ml of Br2 under about 2ml of water, but it`s plenty enough to make a good T spoon of Eosin when dried.

you`ll find that Ammonia added to eosin makes it Really Pink too :)

Chlorox bleach (NaOCl) will remove inevitable stains that occur but be patient, it`s not instant :)

indigofuzzy - 15-3-2007 at 00:06

As for other non-toxic fluorescent compounds, there is Methyl Salicylate (aka oil of wintergreen).

Btw, if you'nz can forgive me for asking: What compound makes semen fluorescent?

Pyridinium - 16-3-2007 at 16:56

if you want an easy source of erythrosin, just use red food coloring. It's mixed with an azo dye though (allura red).

When I'm done w/ stained glassware, caps, droppers, etc, I just leave them in a beaker of bleach for about 4 hrs (though I notice a peculiar trace odor that's not entirely chlorine- anyone know offhand what that is?)

For clothing and other surfaces I don't know what to use w/o destroying them, though Oxy-Clean might work :-D

Edit: joeflsts, I like your lab write up and pics. Will have to try that experiment when I get the time.

[Edited on 19-3-2007 by Pyridinium]

Fluorescein Preparation

joeflsts - 17-3-2007 at 05:48

Since this topic came up I have been fascinated with the preparation of Fluorescein. I have attached my preparation for anyone interested.

Joe

Attachment: Fluorescein.pdf (316kB)
This file has been downloaded 5288 times

woelen - 7-10-2007 at 12:33

I have done a preparation, which does not require the use of ZnCl2. I did not isolate the fluorescein, but unmistakenly, fluorescein is formed. This prep is analogous to the prep of phenolphtalein from phenol and phtalic anhydride with conc. H2SO4. This preparation of fluorescein is a nice experiment on its own. I made a web page about this.

http://woelen.scheikunde.net/science/chem/exps/fluorescence/...

indigofuzzy - 3-4-2008 at 04:19

It's a bit of an odd question, but can anyone recommend an assay for fluorescein? I have some fluorescent yellow-green ink whose composition I have been curious about. The intent of this is my exploration of copper salts, to see if the Copper(II) salt of flourescein is fluorescent, if it makes nice crystals, etc.

YT2095 - 3-4-2008 at 04:41

well, Fluorescein is just Barely soluble in water, most will just sink or float on the top as a red/brown powder.
the addition of Copper Carbonate will help it dissolve a little better but still only slightly more, and the color of the water soln doesn`t look any different than if you use NaOH to me.

woelen - 3-4-2008 at 04:54

The sodium salt does dissolve quite well though. So, I can imagine, that is you add a copper(II) solution to a solution of a sodium fluorescein salt solution, that a precipitate is formed. I have strong doubts on its fluorescence though, but it would be a nice experiment. One has to be careful then using a slight excess of fluorescein with respect to NaOH, otherwise you just make impure copper(II) hydroxide.

indigofuzzy - 3-4-2008 at 17:50

@yt2095 does that mean that Copper(II) fluorescein is water soluble?

indigofuzzy - 5-4-2008 at 07:49

I've tried a few experiments with the fluorescent ink: added it to a CuSO4 solution, which turned emerald green with no ppt. crystallized into a green mass with blue fluorescence. added it to a soln of MgSO4, which stayed about the same color. fluorescence is intensely green when in solution, and pale blue when soaked into filter paper and dried.
added it to a soln of FeSO4, which resulted in a yellow-brown ppt, leaving the liquid phase very pale yellow. The liquid phase is still intensely fluorescent, the ppt is not.
also tried adding the ink to a slurry of Ca(OH)2 in excess water. No visible change to the liquid phase, but the remaining solids have taken on a yellow color. the liquid phase still has strong yellow-green fluorescence, but the solids now glow white (with a near-UV led) or pale yellowish (with a blacklight tube)

Side-notes: the fluorescent ink is from a Sharpie(tm) accent hi-lighter. Fluorescence has been tested with a 380nm near-UV LED, as well as with an 18" household "Blacklight" tube.

YT2095 - 5-4-2008 at 09:09

Quote:
Originally posted by indigofuzzy
@yt2095 does that mean that Copper(II) fluorescein is water soluble?


all I can say with any certainty is that my fluorescein (as the free acid) is hardy water soluble at all, and the addition of copper carbonate allowed more to dissolve.

And that the resulting soln was not any different in color to me than if I`d used NaOH, there was also plenty of undissolved material even after heating.

Zephyr - 3-11-2013 at 19:04

NightHawkInLight recently posted an informative and repeatable video on youtube about how to extract fluoroscein from highlighters markers. After following his procedure i had a total yield of 1.83 grams of fluoroscein. The best thing about his procedure is the fact that the only materials needed are available OTC and the procedure is simple and easily reproduced.
My father is a ground water geologist and uses fluoroscein and many other tracers in his work. Another aesthetic dye he works with is Rhodamine-6G, I'm not sure if this can be synthesized by the amateur but it can be purchased inexpensively on eBay.

Rhodamine:
http://en.wikipedia.org/wiki/Rhodamine
Extract Fluoroscein:
http://www.youtube.com/watch?v=zIpoLiesBgg