Standard Methods: 4500-NH3 C: Ammonia by Titration
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Official Method Name
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4500-NH3 C. Titrimetric 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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Titration with Color Indicator |
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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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Ammonia is titrated with standard sulfiuric acid using a mixed indicator of methyl red and methylene blue. |
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Scope and Application
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The titrimetric method is used only on samples that have been carried through preliminary distillation (see Section 4500-NH3 B). |
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Applicable Concentration Range
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5 - 100 mg N/L |
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Interferences
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Interferences are removed by preliminary distillation. |
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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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Most reliable results are obtained on fresh samples. If samples are to be analyzed within 24 h of collection, refrigerate unacidified at 4 degrees C. For preservation up to 28 d, freeze at -20 degree C unacidified, or preserve samples by acidifying to pH < 2 and storing at 4 degree C. If acid preservation is used, neutralize samples with NaOH or KOH immediately before making the determination. CAUTION: Although acidification is suitable for certain types of samples, it produces interferences when exchangeable ammonium is present in unfiltered solids. See 4500-NH3 A. |
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Maximum Holding Time
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28 days (acidified or frozen); 24 hours (refrigerated) |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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See 4500-NH3 B Preliminary Distillation |
