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[EytchToEssoFor]

i am using luminol, DMSO, H2O2, NaOH, and Bleach.  the longest i can get the reaction to occur is about 10 seconds.  our chemistry department is a joke and i can't get help any other way, but i really want to understand what is going on in this reaction.  any help is greatly appreciated.

[fledarmus]

Do you know the mechanism for the reaction? Do you have any ideas why the reaction is stopping?

[Babcock_Hall]

Different substances give slightly different behaviors with respect to the luminol reaction.  I'll see whether or not I can turn up an appropriate reference later on.  There is a good review article in Talanta by Fillipo Barni and coauthors, and several articles by Creamer and coauthors in forensics journals. 

BTW, there is a curious issue with luminol and bleach.  When you apply bleach to a surface, its ablility to bring about the luminol reaction decreases markedly over the course of hours, until after a day or two, there is little or no detectable reaction.

[EytchToEssoFor]

im guessing that the luminol is being used up, thus the reaction stops.  i know the reaction has something to do with the presence of oxygen, but beyond that, no idea.  when i add H2O2 to the luminol solution i get a quick, bright reaction when the bleach is added.  with the sodium hydroxide it lasts a bit longer, but still, we're supposed to get at least 10 minutes, and the most we've gotten is about 10 seconds. 

[Babcock_Hall]

I am behind at work, but I can just spare the time for some quick thoughts.  Blood gives a relatively long-lasting reaction with luminol, but I don't recall that it lasts 10 minutes.  Animal blood should work just as well as human blood.