I am quantifying the nitrate content in effluent samples using a UV-visible spectrophotometer, as the effluent in question has a high ammonia content, would you like to know whether the reading of nitrate by the spectrophotometer can be influenced by the presence of ammonia?
What method and at what wavelength you define the content of nitrates?
I am using the Pastel-UV apparatus, which is a spectrophotometer that makes readings in the visible region between 200 and 350 nm.
Dear Marcio
According to APHA AWA Standard methods (4500-NO3-B) you can determine nitrate concentration using a UV spectrophotometer. You have to subtract the absorbance reading at 275 nm from the reading at 220 nm after a procedure( dilution, filtration and acid addition to samples). This procedure can eliminate the effect of interferes on nitrate determination.
Perfectly, but the equipment does not give me that possibility. The spectrophotometer is a direct reading, I can not choose the wavelength for an already established reading.
Dear Marcio
1) measure the concentration of the NO3 in effluent, using the Pastel-UV apparatus;
2) add to the cuvette with effluent a few drops of Ammonium hydroxide solution (30-32% NH4OH)- Ammonia aqueous, Ammonia water;
3) again, measure the concentration of nitrates.
If the the concentration of nitrates does not change - the presence of ammonium ion is not affected.
Success in researches!!!!
In my opinion the effect of organic matters is more significant than ammonia. TOC determination is performed in 254 nm (in Pastel-UV) which means you can modify the standard methods and check if the answers is ok or not. subtract absorbance Reading of nitrate from the reading of TOC but you have to calibrate the modified method with standard nitrate solution first.
Dear.
Perfectly!
Grateful for suggestions and considerations, they are very valid.
I will follow your guidance.
Thank you very much.
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