EPA-NERL: 353.1: Nitrate-Nitrite by Colorimetry
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Official Method Name
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Nitrogen, Nitrate-Nitrite (Colorimetric, Automated Hydrazine Reduction) |
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Current Revision
| Issued 1971; Reissued with Revision 1978 |
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Media
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WATER |
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Instrumentation
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Automated Spectrophotometer |
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Method Subcategory
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Inorganic |
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Method Source
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Citation
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Brief Method Summary
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Nitrate in a sample is reduced to nitrite using hydrazine sulfate and the nitrite in the sample (originally present plus reduced 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. This automated procedure can measure approximately 20 samples per hour. |
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Scope and Application
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This method determines nitrate and nitrite in drinking and surface water; domestic and industrial wastes. |
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Applicable Concentration Range
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0.01 - 10 mg/L nitrate-nitrite nitrogen |
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Interferences
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(A) Color: Sample color that absorbs in the range used for analysis will interfere. (B) Sulfide: Nitrate and nitrite concentrations can vary up to 10% with concentration of sulfide ions up to 10 mg/L. |
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Quality Control Requirements
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None. |
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Sample Handling
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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. |
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Maximum Holding Time
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28 Days (nitrate+nitrite)(MCAWW, Table 1). |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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None. |
