Should I go for kjeldahl method or Ion chromatography ?. or any other methods which is more reliable.
https://www.megazyme.com/ammonia-assay-kit
2/24/24
Dear Abrar,
Are you trying to determine the concentration of free NH3 in a solution containing urea, or are you trying to determine the amount of urea by releasing the NH3 from the urea and measuring that?
There is an enzymatic method for detecting free NH3. It is sold by Megazyme (Check their website: https://www.megazyme.com/ammonia-assay-kit). I have used it many times. It is quick and easy to do, and very sensitive. All you need is a spectrophotometer. I have never used it to detect NH3 in the presence of urea, so I don't know if urea interferes. Megazyme's website should provide information about substances/conditions that cause interference.
If you are trying to measure the urea content by converting it to NH3, treat the urea w/ urease first, then you can measure the liberated NH3 w/ the enzymatic kit.
You can also do the Kjeldahl method if you prefer. You can first combust the sample w/ H2SO4. This converts the nitrogen in the sample to (NH4)2SO4. You can avoid the time-consuming distillation and titration steps by measuring the NH3 directly using the enzymatic method. Besides the (NH4)2SO4, your sample will contain leftover H2SO4. However, the buffer in the enzyme kit is enough to neutralize it and allow for the enzymatic reaction to occur. I have done this before and it works.
Ion chromatography is very sensitive and will also work provided you have access to the instrument.
I hope this information helps you. Good luck w/ your research.
Bill Colonna Dept. Food Science & Human Nutrition, Iowa State University, Ames, Iowa, USA [email protected]
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