USGS Test Method I-2525


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Source:
USGS

Method Name:
Nitrogen, ammonia, dissolved, low ionic-strength, colorimetric, ASF. Official Name: Nitrogen, ammonia, low ionic-strength water, colorimetry, salicylate-hypochlorite, automated-segmented flow

Description:
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).

Scope:
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.

Citation:
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

Interferences:
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.

QC Requirements:
Calibrate instrument using calibration standards (CAL); quality control samples (QCS); and laboratory blanks (LB) analyzed at a minimum of 1 for every 10 samples.

Maximum Holding Time:
30 days

Media:
WATER

Subcategory:
Inorganic

Concentration:
0.002 to 0.30 mg/L

Precision:
Precision based on 22 determinations by single operator.

Detection:
Reporting Level defined as smallest measured concentration of a constituent that may be reliably reported using a given analytical method.

Revision Number:
Mar-86

Analytical testing dots

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Analytical testing dots