Standard Methods: 4500-NO3- H: Nitrate by Automated Hydrazine Reduction
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Official Method Name
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4500-NO3- H. Automated Hydrazine Reduction Method |
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Current Revision
| Standard Methods Online |
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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 is reduced to nitrite with hydrazine sulfate. The nitrite (originally present) plus reduced nitrate is determined by diazotization with sulfanilamide and coupling with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a highly colored azo dye that is measured colorimetrically. |
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Scope and Application
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Nitrate and nitrite in potable and surface water and in domestic and industrial wastes can be determined over a range of 0.01 to 10 mg N/L. |
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Applicable Concentration Range
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0.01 to 10 mg-N/L |
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Interferences
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Sample color that absorbs in the photometric range used will interfere. Concentrations of sulfide ion of less than 10 mg/L cause variations of nitrate and nitrite concentrations of +/- 10%. |
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Quality Control Requirements
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See Section 4020 Quality Assurance/Quality Control. |
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Sample Handling
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Plastic or glass containers. Start nitrate determinations promptly after sampling. If storage is necessary, store for up to 2 days at 4 degrees C; disinfected samples are stable much longer (at least 14 days) without acid preservation (See 4500-NO3- A). |
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Maximum Holding Time
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48 hours (general); 14 days (disinfected) (See 4500-NO3- A) |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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