Hi.
I'm analyzing the unknown solution, where there are NO2- and NO3- together.
In the case of NO2-, I could measure it by Griess test.
And then, I tried to measure NO3- by HPLC with 210 nm. However, as you know NO2- and NO3- have the same absorption wavelength...
Therefore, is there a method to measure the only NO3- in the exist of NO2- and NO3- together?..
I will wait for your reply.
Thank you.
Hello Kim. Thank you for your question and I think I can recommend a suitable method. The photometric determination of (NO2)- according to Griess (or Lunge) is a very well known method. (NO3)- can be reduced quickly and completely to (NO2)- with zinc, so that you can determine the sum of (NO3)- and (NO2)- with an adapted sample preparation with the Griess test. The difference between this sum and the (NO2)- content is then the (NO3)- content. There are instruments that use flow injection analysis and a fixed reduction column to perform exactly this analysis.
Alternatively, (NO2)- can be quickly and completely converted to elemental nitrogen with amidosulfuric acid, so that the sample then only contains the (NO3)-. However, reduction with zinc is then still necessary.
I hope that my answer can help you and wish you much success in your research.
Florian is correct: nitrite will directly form azo dyes, then reduce the nitrate and repeat the test to get the sum of both species
Dear Kim,
many thanks for sharing this very interesting technical question with the RG community. As synthetic chemists we certainly lack the experience in analytical chemistry. However, just came across the following potentially useful literature reference which might help answering your question (in addition to the valuable answers provided by Florian and Paul):
A Rapid, Simple Spectrophotometric Method for Simultaneous Detection of Nitrate and Nitrite
Article A Rapid, Simple Spectrophotometric Method for Simultaneous D...
Unfortunately this relevant article has not yet been posted as public full text on RG. However, two of the authors are RG members. Thus there is a good chance that you can request the full text directly from one of these authors via RG.
Good luck with your work and best wishes!
Dear Kim
Many thanks for your nice question and highly appreciated the professional answers , Yes you can determine both ( Nitrate and Nitrite) as the same time by different indicators and method as we have done it many times, Please kindly follow the attached file in Food Stuff and in drinking water or any other solution you can follow the AOAC !As dear Dr Florian mentioned, it is possible by the photometric determination of (NO2)- according to Griess (or Lunge) is a very well-known method.
Best wishes
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