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| U.S. EPA National Exposure Research Laboratory (NERL) [formerly EMSL] |
| 353.2 |
| Revision 2.0, August 1993 |
| Descriptive Name: Nitrate-Nitrite Nitrogen by Colorimetry Official Name: Nitrogen, Nitrate-Nitrite (Colorimetric, Automated, Cadmium Reduction) |
| Media: WATER |
| Inorganic |
| Methods for the Determination of Inorganic Substances in Environmental Samples (EPA/600/R-93/100) |
 Download full method now (PDF file) |
| 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. |
| This method pertains to the determination of nitrite singly, or nitrite and nitrate combined in surface and saline waters; and domestic and industrial wastes. |
| 0.05 - 10 mg/L |
(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. |
| Not included. |
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. |
28 Days (nitrate+nitrite)
48 hours (nitrate or nitrite, singly)
(MCAWW, Table 1). |
| $51 to $200 |
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