MadHatter - 23-1-2005 at 06:07
I suspect that my bottle of indigo carmine solution has undergone oxidation because
over a period of several months it changed from its deep blue color to purple. I keep it
in a 250 ml reagent bottle with a frosted glass stopper. Does anybody know if this
substance reacts to visible light ? I ask because it seems unlikely that oxygen could
get past that stopper. One possible culprit is the electrostatic air purifier I keep in my
room. It produces trace amounts of ozone.
sparkgap - 23-1-2005 at 08:19
MSDS says it's light sensitive...
http://www.jtbaker.com/msds/englishhtml/i1440.htm
UV is the worst offender for this compound.
(edit)
Oh, and it oxidizes easy, too...
sparky
P.S. Next time, use an amber bottle. Photodegradation really is a drag...
[Edited on 23-1-2005 by sparkgap]
Marvin - 23-1-2005 at 12:16
Microbial action, and a dozen other 'natural' things will also reduce it, but this should reoxidise on contact with air.
Indigo Carmine
MadHatter - 24-1-2005 at 10:28
Sparkgap, thanks for the info. I have plenty of IC in solid form to make more solution.
The light sensitivity aspect took me by surprise considering this compound is often
used as a dye. That's probably the case because I don't think oxygen or ozone will get
by that stopper easily.
Since this particular batch has already changed to purple, I'll let it continue to see
the longer term effects and report back on what happens.
Thanks Again !
[Edited on 24-1-2005 by MadHatter]