What type of NH3 test is this?

[Bol]

Hello,

I recently set up a tank, and for various reasons, I used AmQuel to condition the water at the beginning. I now know that AmQuel will cause false readings on Nessler based ammonia tests. I also read (from the AmQuel site) that Nessler tests usually use an amber -> green color scale.

So, I went out and bought a TetraTest NH3/HN4+ test kit. However, there doesn't seem to be any info on this test kit on the Tetra site, so I'm wondering which type of test it is (Nessler or the ... umm... saly-something test).

It reads on a pea green -> blue scale. It's also done with three reagents:

The first is unlabelled,
The second contains phenol (carbolic acid), sodium nitroprusside dyhydrate, and isopropanol.
The third contains lithium hydroxide and sodium hypochlorite solution.

Can anyone tell me which 'type' of test the TetraTest one is?

 

[andyt_uk]

remembering my days @ uni drin... i mean studying chemistry, i think you must mea salycilic sp? acid which smells like deep heat rub for your bad back cant recal its other name nor how it culd test for ammonium compounds, but if either of the solutions smell like that thn you may have the correct stuff ?.... or i could be talking rubbish maybe you should wait for someone else to reply

 

[Bol]

Looked it up again, and on the AmQuel site, it recommends "salycilate type" test kits.

Still wondering if the TetraTest one is the correct one -- I have a concern I may be getting 'false positives' (although, somewhat oddly, the Nessler test is definitely NOT showing a false positive, which I've heard is the most common problem with using that type of test with a product like AmQuel).

 

[Bol]

Well, I found the answer...

The TetraTest kit is the "salycilate type".

However, this is the (seemingly) strange part:

My TetraTest kit, earlier today, showed a noticeable amount of ammonia (between the 0.25 and 1.0 ppm colors), but my Nessler kit showed very close to zero (that is, it wasn't quite clear, but no where near what I'd call any 'color').

The way I thought I understood things, Nessler kits will give false, *high* readings with products like AmQuel because that test will show all ammonia, not just the, umm, 'unlocked' (I don't know the proper term) ammonia. It would seem the results may be a false *low* reading.

So, I'm still sort of confused, but will just continue to monitor the water.

 

[joshua]

i'm kinda assuming ur phenol is phenolphtalin... which is used to test for akalinity i think (its an indicator)... NH3 = ammonia, NH4 = ammonium

 

[andyt_uk]

thats right phenolphthalein turns pink in alkali solutions pH > 7
ammonia NH3 will take up free H+ ions in the water (H2O) to form NH4 which in turn combines with the OH- ions in water to form NH4OH (ammonium Hydroxide)
which if you add to fat creates a soapy substance.. (watch fight club )
methyl salycilate (similar in comosition to aspirin) eractis with alikali solutions to release salicylic acid (2-hydroxybenzoic acid) which is not very soluable in water.

i image therefore that these kind of tests measure the 'cloudiness' of the reagent solution indicating how much salicylic acid has been produced and hence how alkali your solution was (a good indicator of how much NH3 was present)

AND that concludes todays chemistry lesson