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NO@/NO3 Preserved Sample Analysis Quantification
PHanners
Posted: Friday, November 5, 2010 9:08 AM
Joined: 11/5/2010
Posts: 2


When a aquaous sample is preserved for NO2/NO3 H2SO4 , Most if not all of the nitrite is destroyed. Since the Nitrite can not be quantitated ( Acidified nitrite standard typically not stable) should'nt the sample analysis be qualified?


dsmith
Posted: Friday, November 5, 2010 11:57 AM
Joined: 12/31/2009
Posts: 40


Typically when the sample is preserved you are looking for NO2+NO3, or in other words the sum of both species.  Preserving the sample does not 'destroy' the nitrite, rather it is converted from NO2 to NO3.  If you are looking to quantify the individual components there is no preservative recognized by the EPA and you must analyze the sample within 48 hours from collection.

 


PKHanners
Posted: Friday, November 5, 2010 12:27 PM
Joined: 11/5/2010
Posts: 1


PHanners wrote:

When a aquaous sample is preserved for NO2/NO3 H2SO4 , Most if not all of the nitrite is destroyed. Since the Nitrite can not be quantitated ( Acidified nitrite standard typically not stable) should'nt the sample analysis be qualified? I orginally thought that the nitrite would be preserved equivlent to the nitrate. What I found was that it is not. If you acidify a nitrite standand equivlent to a preserved sample you will find that it does not convert to nitrate but rather quickly degrades. It does not show up as nitrate. Since runing across this I have had this confirmed from three other sources. It is usually not an issue due to the lack of most samples containing nitrite at any significent levels.