[BPEARCE]

Hello All,

I am looking to distinguish amines from ammonia present in purified water.

We are getting a postive result for ammonia, but are pretty sure it is amines giving a false positive.

Any ideas?

thanks in advance

Ben

[Honclbrif]

What test are you using? Why do you think it's amines and not ammonia? Any idea what amine(s) it might be?

You might be able to make the sample basic with NaOH or KOH to volatilize the basic nitrogen compounds and analyze the headspace by GC-MS.

[BPEARCE]

We are using Alkaline Potassium tetraiodomercurate for the ammonia test.

The filters we use have data saying one of the leachables is a amine from nylon used in construction, which is acceptable.

However there should be no ammonia present.

Thanks again

Ben

[Honclbrif]

Can't say I'm familiar with the Alkaline Potassium tetraiodomercurate test.

Unless your solution is very acidic or basic, I wouldn't expect you would leach very much amine out of your nylon filters, it should all be bound up as polymer. However, the filters may have been made with cheap nylon that was not completely processed to remove all excess monomer.

Have you tried flushing one with distilled water that you know to be free of ammonia and amines, then testing it? Or, just flushing with water to remove the excess amine. Any excess amine should come out fairly easily with mildly acidic water, then reequilibrate with distilled water. Alternatively, there are all sorts of filters out there from regenerated cellulose to PTFE. Perhaps one of those would give better results.

[BPEARCE]

I didn't know it either, but its one we have to use.

We can't change filters and its only in the first 500ml we see the contaminant, so we are just flushing to waste. But the rules say we need to find out exactly where its coming from.

Is there a test that wouldn't free the amines and only test the free ammonia? Then we could compare to our test and could say that anything in the second test must be amines giving a ammonia false positive

Regards

Ben