NightHawkInLight Posted July 9, 2013 Posted July 9, 2013 I'm attempting to remove fluorescein from solution in a powder form, but every time I boil it down to the point where the fluorescein starts to fall out of solution and turn the mix into a grainy slush the evaporation ceases and the slush will dry no further even in several hours time. For some reason or another I can only drive off enough water that it seems half of the fluorescein falls out of solution, but the other half hangs on to enough water to cause everything to swim. If I raise the temperature any more once the mix is at this point the fluorescein will melt and form into a sticky caramel that still has high water content, and even if somehow dried I suspect would be very difficult to turn back into powder or even granules. Raising the temperature even further from the caramel state just causes smoke and I'm afraid a loss of product. Any ideas for how I might dry this stuff out?
NightHawkInLight Posted July 9, 2013 Author Posted July 9, 2013 I just preformed a little test that might have just shed more light on my situation. It seems the fluorescein I am trying to dry is not soluble in alcohol, while a sample I purchased in a pure form is. Perhaps what I am trying to dry is contaminated with another chemical that is coating it to cause the low alcohol solubility and causing the stickiness and smoking when I hit higher temperatures. I don't think I'm hitting the actual melting point of the fluorescein itself so I suppose that makes sense. The source for the chemical may have included a binder that is causing my problems. I could push the temperature a bit further to find out where it gets me in burning the offending chemical away but that could potentially ruin things as well or at least give off some nasty unknown things in the smoke. A solvent for the containment would be preferable to burning it, if a contaminant really is the issue like I think it may be.
pyroman2498 Posted July 9, 2013 Posted July 9, 2013 Have you tried a desiccator bag, like the one nurdrage made? I've never ran into this problem with a chemical in my Ochem lab so i'm not too sure. If you can't get an answer here try out the ScienceMadness forums , they will definitely be able to help you out. Anyways, thats all i could really think of , i might be able to think of something else when i get some sleep Take care and stay safe. ~Steven
NightHawkInLight Posted July 9, 2013 Author Posted July 9, 2013 I've confirmed that my issue is contamination with a binder. Looks like my mistake was to collect the fluorescein using water which the binder is evidently also soluble in, whereas alcohol leaves the binder behind if I use it before the solution is heated. Guess I'm starting my experiment over again.
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