Method 353.2

Nitrogen, Nitrate-Nitrite (Colorimetric, Automated, Cadmium Reduction)

This method is for the determination of nitrite singly, or nitrite and nitrate combined in surface and saline waters, and domestic and industrial wastes.  A filtered sample is passed through a column containing granulated copper-cadmium to reduce nitrate to nitrite. The nitrite (that originally present plus reduced nitrate) is determined by diazotizing with sulfanilamide and coupling with N-(1-naphthyl)-thylenediamine dihydrochloride to form a highly colored azo dye which is measured colorimetrically. Separate, rather than combined nitrate-nitrite, values are readily obtained by carrying out the procedure first with, and then without, the Cu-Cd reduction step.

The applicable range of this method is 0.05 to 10.0 mg/L nitrate-nitrite nitrogen. The range may be extended with sample dilution.

High concentrations of iorn, copper or other metals can interfere with the anlaysis.

(EPA: Office of Water)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   28 days from sample collection to analysis for nitrate and nitrite. 48 hours from sample collection to analysis if doing nitrate only or nitrite only.
Preservatives:   Refrigerate samples 4°C. If samples will be stored for more than 24 hours, preserve with sulfuric acid (2 mL concentrated, per liter) and refrigerate.
Required Preps:   250 mL HDPE or amber glass bottle
Collection Method:   Grab sampling
Analytical Methodology:   Colorimetry
Documentation:   353.2

Analyte List*

Analyte Formula CAS Number Detection Limit

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.