Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Geezer on 16/11/2010 06:49:33

Title: What are nitrites? How do they get into water and why test for them?
Post by: Geezer on 16/11/2010 06:49:33: We receive our water from a well that belongs to a community water association. It supplies around thirty homes. Recently, I got stuck with taking samples to the local lab for testing.

Every three months we have to submit a sample for bacteria testing, which seems like a good idea.

Every year the nitrate level has to be quantified, which I vaguely understand.

I recently discovered that every nine years, the nitrite level has to be quantified, about which I have no clue.

Can anyone clue me in?
Title: What are nitrites? How do they get into water and why test for them?
Post by: Bored chemist on 16/11/2010 19:55:29: Nitrites are a bit like nitrates. They are the salts of nitrous acid, rather than nitric acid.
An example would be sodium nitrite NaNO₂ (sodium nitrate is NaNO₃ for comparison).
They may be produced by bacterial reduction of nitrates and they can react with a common group of chemicals (called secondary amines, but you don't need to remember that. I'm not setting a test at the end)
That reaction produces a nitrosamine and a lot of the nitrosamines have been found to be carcinogenic.
It's easier to test for the nitrite than for all the possible nitrosamines (particularly since the nitrosamines might only be formed when the nitrites in water react with amines in food).

Does that answer the question?
Title: What are nitrites? How do they get into water and why test for them?
Post by: Geezer on 16/11/2010 23:24:38: Thanks BC. That does make sense. Any thoughts on why the health district only requires testing for nitrites every nine years?
Title: What are nitrites? How do they get into water and why test for them?
Post by: Bored chemist on 17/11/2010 19:16:04: I don't really know but my guess is that it's more difficult and, unless you have the nitrates and the right bugs, it's pointless.
Title: What are nitrites? How do they get into water and why test for them?
Post by: lightarrow on 21/11/2010 13:28:45: Quote from: Geezer on 16/11/2010 23:24:38
Thanks BC. That does make sense. Any thoughts on why the health district only requires testing for nitrites every nine years?
That's quite strange infact. In the county I live, nitrites are analyzed in drinking water always for a specific area (greater risk of contamination from factory farms) and never in the other areas.