ISO 23696-1:2023
(Main)Water quality — Determination of nitrate in water using small-scale sealed tubes — Part 1: Dimethylphenol colour reaction
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 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.
Qualité de l'eau — Détermination du nitrate dans l'eau par la méthode à petite échelle en tubes fermés — Partie 1: Réaction colorimétrique au diméthylphénol
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 23696-1
First edition
2023-02
Water quality — Determination of
nitrate in water using small-scale
sealed tubes —
Part 1:
Dimethylphenol colour reaction
Qualité de l'eau — Détermination du nitrate dans l'eau par la
méthode à petite échelle en tubes fermés —
Partie 1: Réaction colorimétrique au diméthylphénol
Reference number
ISO 23696-1:2023(E)
© ISO 2023
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ISO 23696-1:2023(E)
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© ISO 2023
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ISO 23696-1:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 2
5 Interferences . 2
6 Sampling and sample preparation . 3
7 Reagents and standard solutions . 3
8 Apparatus . 3
9 Procedure .4
9.1 Reaction conditions for the colour reaction . 4
9.2 Dimethylphenol based colour reaction . 4
10 Quality control . 4
10.1 V erification of the calibration . 4
10.2 System and interferences checks . 5
11 Calculation . 5
12 Expression of results .5
13 Test report . 6
Annex A (informative) Performance data . 7
Bibliography . 8
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ISO 23696-1:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods.
A list of all parts in the ISO 23696 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO 23696-1:2023(E)
Introduction
Nitrate plays an important role in nature and are naturally present in ecosystems. The main anthropic
sources are agriculture (fertilizers and manure) and industrial sources such as food, chemical, paper
companies, etc. and as a result of natural nitrification processes of reduced forms of nitrogen. In turn,
nitrate can be converted to nitrogen gas by denitrifying bacteria. This process takes on strategic
importance within biological water purification plants.
The presence of significant concentrations of nitrate in surface and bathing water, drinking water and
wastewater can pose a risk to human health and/or environment.
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INTERNATIONAL STANDARD ISO 23696-1:2023(E)
Water quality — Determination of nitrate in water using
small-scale sealed tubes —
Part 1:
Dimethylphenol colour reaction
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document
be carried out by suitably qualified staff.
1 Scope
This document specifies a method for the determination of nitrate as NO -N in water of various origin
3
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 N0 -N using the
3
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 NO - after conversion with
3
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, NO without indication of the negative charge has become the common notation for the parameter
3
nitrate and especially for the parameter nitrate-N. This notation is adopted in this document even though not
being quite correct chemical nomenclature.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste water
ISO 8466-1, Water quality — Calibration and evaluation of analytical methods — Part 1: Linear calibration
function
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ISO 23696-1:2023(E)
ISO 8655-2, Piston-operated volumetric apparatus — Part 2: Pipettes
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
small-scale sealed tube
glass tube commercially available on the market, prefilled by the manufacturer with reagent(s), to
develop a colour to be read by a photometer or a spectrophotometer
4 Principle
Nitrate content o
...
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