scope:

This document specifies a method for the determination of nitrate as NO3-N in water of various origin 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 N-N03 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. Concentrations even slightly higher than the upper limit indicated in the manufacturers manual relating to the small‑scale sealed tube method used, cannot be reported as accurate results. Appropriate preliminary dilution of the sample shall be performed or a small‑scale sealed tube method with a different application measuring range shall be used. Manufacturers' small-scale sealed tube methods are based on chromotropic colour reaction, depending on the typical operating procedure of the small‑scale sealed tube used , see Clause 8. If required by laws, regulamentations or standards, the data can be expressed as NO3 after conversion with the stoichiometric conversion factor 4,426 81, see Clause 10.