Standard Methods: 4500-NO3- E: Nitrate in Water After Cadmium Reduction
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Official Method Name
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Nitrate in Water by Colorimetry and Cadmium Reduction |
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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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Spectroscopy (Colorimetry; Photometry) |
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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 almost quantitatively to nitrite in the presence of Cd. The nitrite thus produced is determined by diazotizing with sulfanilamide and coupling with N-(1-napthyl)-ethylenediamine dihydrochloride to form a highly colored azo dye that is measured colorimetrically. |
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Scope and Application
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This method allows for determination nitrate and nitrite in water. This method will determine between 0.01 and 1 mg NO3-N/L. |
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Applicable Concentration Range
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0.01 - 1.0mg/L |
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Interferences
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(1) Suspended matter restricts sample flow. (2) Metals (e.g., iron, copper) lower reduction efficiency. (3) Oil & Grease which coats the column. (4) Residual chlorine which oxidizes the reduction column. (5) Colored samples that absorb at ~540 nm. |
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Quality Control Requirements
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None |
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Sample Handling
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Collect 100 mL sample in a plastic or glass container. When storing sample for > 1 day, preserve with 2 mL concentrated H2SO4/L. Refrigerate at 4 C. Individual species NO3- and NO2- cannot be determined from preserved samples. Analyze within 48 hours. |
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Maximum Holding Time
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48 hours |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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