USGS-NWQL: I-2525: Nitrogen, ammonia, dissolved, low ionic-strength, colorimetric, ASF
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Official Method Name
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Nitrogen, ammonia, low ionic-strength water, colorimetry, salicylate-hypochlorite, automated-segmented flow |
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Current Revision
| Mar-86 |
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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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M.J. Fishman, 1993, Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory--Determination of inorganic and organic constituents in water and fluvial sediments: U.S. Geological Survey Open-File Report 93-125 |
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Brief Method Summary
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Ammonia reacts with hypochlorite and salicylate ions in the presence of ferricyanide ions to form the salicylic acid analog of indophenol (Reardon and others, 1966; Patton and Crouch, 1977; Harfmann and Crouch, 1989). |
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Scope and Application
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This method is used to analyze samples of precipitation and natural water containing from 0.002 to 0.30 mg/L of ammonia-nitrogen. Concentrations greater than 0.30 mg/L must be diluted. This method was implemented in the National Water Quality Laboratory in March 1986 and modified in May 1989. |
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Applicable Concentration Range
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0.002 to 0.30 mg/L |
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Interferences
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No substance found in natural water seems to interfere with this method. The samples are easily contaminated by ammonia in the laboratory atmosphere; therefore, sample handling and analysis need to be performed where there is no possibility of ammonia contamination. |
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Quality Control Requirements
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Calibrate instrument using calibration standards (CAL); quality control samples (QCS); and laboratory blanks (LB) analyzed at a minimum of 1 for every 10 samples. |
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Sample Handling
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Container Description: 125 mL brown polyethylene bottle. Treatment and Handling: Filter through 0.45 micron filter; use filtered sample to rinse container; preservation with mercuric chloride; chilled to 4 degrees C and ship immediately. |
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Maximum Holding Time
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30 days |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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