Hach 10206

Determination of Nitrate Nitrogen

Applicability: This procedure applies to water samples, domestic and industrial aqueous waste samples received or generated by Conti Testing Laboratories, Inc. (CTL), Pittsburgh, Pennsylvania.
1.1. Method Reference: Hach 10206
1.2. Summary: Determination of nitrate is difficult due to the relatively complex procedures required, the high probability of interfering constituents present, and the limited concentration ranges of the techniques. In the colorimetric method, nitrate ions in solutions containing sulfuric and phosphoric acids react with 2,6-dimethylphenol to form 4-nitro-2,6-dimethylphenol. The wavelength for measuring the nitrate is 345 nm.
1.3. Matrix or Matrices: Water and aqueous wastes.
1.4. Quantitation Range: 0.23 to 35 mg/L.
1.5. Holding Time: Analyze immediately, if possible, within 48 hrs of sample collection and report as nitrate; if longer storage is required (up to 28 days), preserve with H2SO4 to a pH of <2 and report as nitrate-nitrite.
1.6. Preservation: Refrigerate at 4° C ± 2oC.
1.7. Interferences
1.8. Sample collection and shipment: Unpreserved, plastic or glass; refer to field methods for sample collection.

Purpose: The purpose of this procedure is to provide a method of determination of nitrate in aqueous domestic and industrial waste samples. This method is not approved for NPDES samples in the state of Pennsylvania.