NEMI Method Summary

Method Summary Information

Method Number: 353.2 Media: WATER
Revision: Revision 2.0, August 1993
Method Source: U.S. EPA National Exposure Research Laboratory (NERL) [formerly EMSL]
Analytes in this method
Subcategory: INORGANIC
Official Name: Nitrogen, Nitrate-Nitrite (Colorimetric, Automated, Cadmium Reduction)
Descriptive Name Nitrate-Nitrite Nitrogen by Colorimetry
Source Info: U.S.EPA National Exposure Research Laboratory (NERL)
Microbiological and Chemical Exposure Assessment Research Division (MCEARD)
[formerly the Environmental Monitoring Systems Laboratory (EMSL), Cincinnati, OH]
26 West Martin Luther King Drive
Cincinnati, Ohio 45268-0001
Fax: 513-569-7757
email: DWmethods.help@epa.gov
Citation: Methods for the Determination of Inorganic Substances in Environmental Samples (EPA/600/R-93/100)
214130 Byte file
Brief Method
Summary:
 A filtered sample is passed through a column containing granulated copper-cadmium to reduce nitrate to nitrite. The nitrite (that originally present plus that reduced to nitrate) is determined by diazotizing with sulfanilamide and coupling with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a highly colored azo dye which is measured colorimetrically. Separate, rather than combined nitrate-nitrite, values are readily obtained by carrying out the procedure first with, and then without, the Cu-Cd reduction step.
Scope And
Application:
 This method pertains to the determination of nitrite singly, or nitrite and nitrate combined in surface and saline waters; and domestic and industrial wastes.
Applicable
Conc Range:
 0.05 - 10 mg/L
Interferences: (1) Build up of suspended matter in the reduction column will restrict sample flow. Since nitrate-nitrogen is found in a soluble state, the sample may be pre-filtered.
(2) High concentrations of iron, copper, or other metals.
(3) Large concentrations of oil and grease will coat the surface of the cadmium.
QC Requirements: Not included.
Sample Handling: If analysis can be made within 24 hours, refrigerating samples at 4oC is sufficient. If samples are kept more than 24 hours, preserve with 2 mL of sulfuric acid per liter of sample and refrigerate.
Do not preserve sample with mercuric chloride if they will be run through the reduction column.
Max Holding Time:
 28 Days (nitrate+nitrite)
48 hours (nitrate or nitrite, singly)
(MCAWW, Table 1).
 
Relative Cost: $51 to $200
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