Hello everyone, this is the first time I'm going to do a Griess assay. I want to know the amount of releasing NO from my solution. I will do reaction between HYDROGEN PEROXIDE and L- arginine. Should i mix the solution (hydrogen peroxide + L-arginine) and Griess reagent? or only the origin solution without Griess reagent? (after that i calculate the concentration using NO standard curve)
Thank you!
Be careful! The Griess assay DOES NOT measure nitric oxide! It measures nitrite (and nitrate, if you use a reductase to convert it to nitrite). Nitrite is an aqueous oxidation product of NO, and can be considered to be an indicator of NO.
I'm not familiar with your reaction, but if NO is being produced, then over time nitrite should accumulate in your solutions. But how much will depend on the rate of production and the oxidation rate, so initially you should probably sample your reaction and use the Griess assay to measure the nitrite content in the media. Of course, the longer you wait, the more nitrite will accumulate and the more likely you are to detect something.
If you actually want to measure NO, you can use a chemiluminescent NO analyzer measure nitric oxide gas, directly. These instruments are used, for example, to measure and quantify gaseous NO in exhaled breath or atmospheric samples. For liquid samples, you need to sparge NO out of the liquid to be analyzed. The setup is a bit complex and samples have to be analyzed in series, but the analyzer is extremely sensitive, down to 1 ppb.
There was report on the NO production from the reaction of H2O2 and L-Arginine. However, our recent experiments on this reaction didn't find any NO production. Hopefully you can help find out the mechanism of this reaction.
For details of our work please see Fig S9 in:
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