ISO 23697-1:2023 PDF

Scope: This document specifies a method for the determination of total bound nitrogen (ST-TNb) in water of various origins: groundwater, surface water, and wastewater, in a measuring range of concentration generally between 0,5 mg/l and 220 mg/l of ST-TNb 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 small-scale sealed tube method of different manufacturers. It is up to the user to choose the small-scale sealed tube with the appropriate application range or to adapt samples with concentrations exceeding the measuring range of a test by preliminary dilution. NOTE The results of a small-scale sealed tube are most precise in the middle of the application range of the test. All small-scale sealed tube methods are based on a heated alkaline potassium persulfate oxidation in a heating block. Different digestion temperatures, 100 °C or 120 °C or 170 °C, and different digestion times are applicable. Dimethylphenol colour reactions are applied, depending on the typical operating procedure of the small-scale sealed tube used, see Clause 9.

ISO 23697-1:2023 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/IEC 17025 General requirements for the competence of testing and calibration laboratories [Standard in French]

2023 ISO 23697-1:2023 Water quality — Determination of total bound nitrogen (ST-TNb) in water using small-scale sealed tubes — Part 1: Dimethylphenol colour reaction