EPA-NERL: 350.2 (Nesslerization): Ammonia by Colorimetry (Nesslerization)
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Official Method Name
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Nitrogen, Ammonia (Colorimetric; Titrimetric; Potentiometric - Distillation Procedure) |
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Current Revision
| Editorial Revision 1974 |
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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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A sample is buffered at alkaline pH with borate buffer to decrease hydrolysis of cyanates and organic nitrogen compounds, and is distilled into a solution of boric acid. The ammonia distillate is determined colorimetrically by Nesslerization, or by other options given in the method. |
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Scope and Application
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This method determines ammonia, exclusive of Kjeldahl nitrogen, in drinking, surface, and saline waters; domestic and industrial wastes. |
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Applicable Concentration Range
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0.05 - 1.0 mg/L ammonia as nitrogen (colorimetric) |
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Interferences
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(A) Compounds 1: Many aromatics, aliphatic amines, and other compounds can cause turbidity upon reaction with Nessler reagent. Distillation is used prior to analysis to reduce/eliminate interferences. (B) Compounds 2: Volatile alkaline compounds (some ketones, aldehydes, and alcohols) can effect Nesslerization. Some compounds (e.g., formaldehyde) can be removed prior to to distillation by boiling off at low pH. (C) Cyanate: Cyanate can hydrolyze during distillation. (B) Residual Chlorine: Remove residual chlorine using sodium thiosulfate. |
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Quality Control Requirements
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None. |
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Sample Handling
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Cool to 4oC, add H2SO4 until sample pH < 2. |
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Maximum Holding Time
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28 days (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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