Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Quantification of nitrite?
silonyl
Harmless
*




Posts: 23
Registered: 18-7-2005
Member Is Offline

Mood: No Mood

[*] posted on 21-2-2006 at 08:15
Quantification of nitrite?


I am looking for a quick and simple method for the quantification of nitrite in solution (or solid), if one exists. What I want is essentially a way to check the purity of a sample of bulk material, which most likely contains only nitrite and water. Dehydration would be acceptible, although I'd prefer a chemical method for didactic reasons.

Since the material is thought to be primarily nitrite, with water as a primary contaminant, quick tests that quantitate nitrate+nitrite would probably be acceptible as well.

Thanks!
View user's profile View All Posts By User
garage chemist
chemical wizard
*****




Posts: 1803
Registered: 16-8-2004
Location: Germany
Member Is Offline

Mood: No Mood

[*] posted on 21-2-2006 at 09:45


Addition of an excess of ammonium salt (e.g. NH4Cl) and heating under stirring until evolution of gas (nitrogen) stops.
The amount of nitrogen evolved is directly proportional to the amount of nitrite contained in the sample.
If (at 0°C) 22,4 L (or 24L at 25°C) of nitrogen are evolved, the test substance contained 1 mol of nitrite ion.
View user's profile View All Posts By User
silonyl
Harmless
*




Posts: 23
Registered: 18-7-2005
Member Is Offline

Mood: No Mood

[*] posted on 21-2-2006 at 10:17


Interesting, although I'm not so much in the mood to set up a gas collection tube unless I have to.

What kind of temperature is needed for this reaction to proceed? Is there a possibility of titrating unknown nitrite with known concentration of NH4Cl or a primary ammonium salt? Or possibly acidifying the nitrite to form HONO and then titrating with ammonia/amine?
View user's profile View All Posts By User
Lambda
International Hazard
*****




Posts: 566
Registered: 15-4-2005
Location: Netherlands
Member Is Offline

Mood: Euforic Online

[*] posted on 21-2-2006 at 14:29
The GRIESS reagent system


The easiest tests that I know for Nitrite Ion determination are based an the formation of the "Azo" compound of a reagent (which often turn red in color). The famous "GRIESS" test is one example of a very specific and sensitive Nitrite determination test, using Sulfanilamide. This is then measured via a Photo Spectrometer. Fishery and Aquarium stores sell similar kits for under $10. Some are even based on the same principle as Litmus Acid/Base test strips, which are compared to a reference color match chart. It can't get much simpler than this, can it.

An example can be found here (AquaTru® Nitrite Test Kit):
http://www.novalek.com/kpd45.htm

And for the "GRIESS" reagent system:
http://www.promega.com/tbs/tb229/tb229.pdf

I have often used the Nitrite determination test by means of the "GRIESS" principle, and it's one of the most sensitive and best I know of to get the job done right.

[Edited on 21-2-2006 by Lambda]
View user's profile View All Posts By User
Microtek
International Hazard
*****




Posts: 647
Registered: 23-9-2002
Member Is Offline

Mood: No Mood

[*] posted on 22-2-2006 at 07:08


You could titrate with acidified KMnO4 if you have a sample of pure nitrite ( or other reducing agent ) to act as primary standard. In acidic solution MnO4- is reduced all the way to colorless Mn2+.
View user's profile View All Posts By User

  Go To Top