Water quality — Determination of nitrate in water using small-scale sealed tubes — Part 2: Chromotropic acid colour reaction
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 small-scale 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 chromotropic 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 Clause 11.
NOTE 3 In the habitual language, use of sewage treatment and on the displays of automated sealed-tube test devices, NO3 without indication of the negative charge has become the common notation for the parameter nitrate and especially for the parameter nitrate-N. This notation is adopted in this document even though not being quite correct chemical nomenclature.