ISO 23696-2:2023
Water quality — Determination of nitrate in water using small-scale sealed tubes — Part 2: Chromotropic acid colour reaction

Standard No.

ISO 23696-2:2023

Release Date

2023

Published By

International Organization for Standardization (ISO)

Latest

ISO 23696-2:2023

Scope

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 0,20 mg/l and 30 mg/l of NO3-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 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 4,42681 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.

ISO 23696-2:2023 Referenced Document

• ISO 5667-1 Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and sampling techniques*， 2023-03-14 Update
• ISO 5667-3 Water quality*， 2024-02-01 Update
• ISO 8466-1 Water quality — Calibration and evaluation of analytical methods — Part 1: Linear calibration function
• ISO 8655-2 Piston-operated volumetric apparatus — Part 2: Pipettes
• ISO/IEC 17025 General requirements for the competence of testing and calibration laboratories [Standard in French]

ISO 23696-2:2023 history

• 2023 ISO 23696-2:2023 Water quality — Determination of nitrate in water using small-scale sealed tubes — Part 2: Chromotropic acid colour reaction