Water quality — Determination of nitrate in water using small-scale sealed tubes — Part 1: Dimethylphenol colour reaction

This document specifies a method for the determination of nitrate as NO3-N in water of various origin such as natural water (including groundwater, surface water and bathing water), drinking water and wastewater, in a measuring range of concentration between 0,10 mg/l and 225 mg/l of N03-N using the small-scale sealed tube method. Different measuring ranges of small-scale sealed tube methods can be required.

The measuring ranges can vary depending on the type of the small-scale sealed tube method of different manufacturers.

It is up to the user to choose the small-scale sealed tube test with the appropriate application range or to adapt samples with concentrations exceeding the measuring range of a test by preliminary dilution.

NOTE 1 The results of a sealed-tube test are most precise in the middle of the application range of the test.

Manufacturers' small-scale sealed tube methods are based on dimethylphenol colour reaction depending on the typical operating procedure of the small-scale sealed tube used, see Clause 9.

NOTE 2 Laws, regulations or standards can require that the data is expressed as NO3- after conversion with the stoichiometric conversion factor 4,426 81 in Clau