Detection of hydrogen peroxide in water

[Topher925]

Main Question or Discussion Point

Is there any relatively not difficult way to detect if hydrogen peroxide (H2O2) is present in pure water? I can think of a few obvious ways for high concentrations but what about concentrations of around 0.001mol%? Is there a way of detecting concentrations that small or smaller?

 

[MATLABdude]

Maybe indirectly using catalase? This should quite efficiently convert any hydrogen peroxide into water and oxygen (which you might be able to capture / measure with a dissolved oxygen meter).

Alternately, given that hydrogen peroxide is such a good oxidizer, maybe do a redox reaction (with appropriate indicators) and see if anything reacts?
http://en.wikipedia.org/wiki/Hydrogen_peroxide#Reactions

 

[Nemus]

The Fenton reaction perhaps? Fe(II) + H2O2 -> OH. + Fe(III) + OH-
OH. + salicylic acid -> 5-hydroxy salicylic acid which you can detect with HPLC. Or do you need something colorimitric?
perhaps I- + H2O2 -> I2
i2 + starch forms intense blue color.

 

[Topher925]

Thanks for the replies. Using some type of redox reaction was my first inclination but wanted to know there's something out there that would better. I like the idea of having a colorimitric reaction as it would make detection very simple. I'll look into it.

 

[Borek]

I took a second look at your question - what do you mean by 0.001mol%?

No matter what you mean, my first impression was that at low concentrations standard approaches are unlikely to work. Amount of oxygen evolving during decomposition can be too low for bubbles to form. On the other hand, solution is most likely already saturated with atmospheric oxygen, so there already is a strong oxidizer in solution - if concentrations are comparable, you may be not able to distinguish between both, unless you will find a highly specific reaction.