USGS-NWQL: I-2540-90: Nitrite in Water by Colorimetry
|
Official Method Name
|
Nitrogen, Nitrite, Colorimetry, Diazotization, Automated-Segmented Flow |
|---|---|
|
Current Revision
| 1993 |
|
Media
|
WATER |
|
Instrumentation
|
Spectroscopy (Colorimetry; Photometry) |
|
Method Subcategory
|
Inorganic |
|
Method Source
|
|
|
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 |
|
Brief Method Summary
|
Nitrite ion reacts with sulfanilamide under acidic conditions to form a diazo compound which then couples with N-1-naphthylethylenediamine dihydrochloride to form a red compound, the absorbance of which is measured colorimetrically (Shinn, 1941; Bendschneider and Robinson, 1952; Fox, 1979, 1985; Pai and others, 1990). |
|
Scope and Application
|
This method is used to analyze samples of surface, domestic, and industrial water and brines containing from 0.01 to 1.0 mg/L of nitrite-nitrogen. Concentrations greater than 1.0 mg/L must be diluted. This modified method was implemented in the National Water Quality Laboratory in March 1988. |
|
Applicable Concentration Range
|
0.01 - 1.0 (undiluted) |
|
Interferences
|
Concentrations of potentially interfering substances generally are negligible. For specific details of inorganic and organic compounds that interfere with the reaction, see Norwitz and Keliher (1985, 1986) as well as more general information from the American Society for Testing and Materials (1991). |
|
Quality Control Requirements
|
Quality-control samples area analyzed at a minimum of one in every ten samples. These QC samples include at least one of each of the following: blanks, quality control samples, third party check solutions, replicates, and spikes. Correlation coefficients for calibration curves must be at least 0.99. QC samples must fall within 1.5 standard deviations of the mean value. If all of the data-acceptance criteria in the SOPs are met, then the analytical data are acceptable. |
|
Sample Handling
|
Description: 125 mL Brown polyethylene bottle. Treatment and Preservation: Filter through 0.45-um filter, use filtered sample to rinse containers, chill and maintain at 4oC, ship immediately. |
|
Maximum Holding Time
|
30 days from sampling |
|
Relative Cost
|
Less than $50 |
|
Sample Preparation Methods
|
