[Senor_D]

Hey all,

I'm working on a procedure right now that involves the detection of indoles using Ehrlich's reagent made with 4-(dimethylamino)benzaldehyde dissolved in 2:1 n-propanol:perchloric acid. A previous paper claims that this reagent is unstable and needs to be made fresh for each experiment. I'm wondering if anyone knows why this might be. Specifically I'd like to know if I can get away with making a stock solution of the n-propanol:perchloric acid beforehand and simply add my dimethylaminobenzaldehyde at the time of the experiment.

Thanks,
Senor

[kiwi]

Specifically I'd like to know if I can get away with making a stock solution of the n-propanol:perchloric acid beforehand and simply add my dimethylaminobenzaldehyde at the time of the experiment.

Bad idea. Any organic/perchlorate mixtures are an explosion waiting to happen. Make your Ehrlichs reagent up with either sulfuric, hydrochloric or phosphoric acid - a quick google uncovered recipes for all three.