Chromatography Forum

Hi, I would like to quantify ammonia in an aqueous solution by HS-GC-MS. I should have the right column, do you think is it possible to perform this analysis or there is some issue (i.e. molecular weight...)?
Thanks!

Why?

Hello, I am trying to detect several organic compoundsin water, among them NH3, but the only instrument I can use is just a GC-MS provided with head-space...I would like to understand the feasiblity before going on. Thank you!

What are the organic compounds?

Hi

There are so many reasons for your suggested GCMS/HS approach for ammonia level in aqueous solution to be loaded with problems !

Ammonia in water is either un-ionized ammonia or the ammonium ion. Typically, the value reported is the sum of both forms and is reported as total ammonia or simply - ammonia. The relative proportion of the two forms present in water is highly affected by pH.

A simple titrimetric method would probably be far more applicable for your query even down to the ppm level in your aqueous solution. Then you can concentrate on the organics determination

In the titrimetric method, a colour indicator is added to an aqueous sample, which is subsequently titrated with 0.02 N H2SO4. At the end point of the titration, the colour of the sample turns to a pale lavender colour. The amount of sulfuric acid used for the colour change is proportional to the amount of in water

See also

http://www.restek.com/compound/view/7664-41-7/Ammonia

and

viewtopic.php?t=18476

For your organic compounds it may well be a suitable approach but, to repeat Steve's request, what are they, at what sort of level and what exactly is your sample?