ISO/FDIS 20236

ISO/TC 147/SC 2/WG 70
Secretariat: DIN
Date: 2024-06-24
Water quality — Determination of total organic carbon (TOC),
dissolved organic carbon (DOC), total bound nitrogen (TNb) and
dissolved bound nitrogen (DNb) after high temperature catalytic
oxidative combustion
Qualité de l’eau — Dosage du carbone organique total (COT), carbone organique (COD), azote lié total
(TN ) et azote lié dissous (DN ) après combustion oxidatif catalytique à haute température
b b
Second edition
Date: 2024-02-27
FDIS stage
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Published in Switzerland
iii
Contents
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Interferences . 3
5.1 General . 3
5.2 TOC or DOC . 3
5.3 TNb or DNb . 4
6 Reagents . 4
7 Apparatus . 7
8 Quality requirements for the analytical system . 9
8.1 System check . 9
8.2 Particle processing control . 9
9 Sampling and sample preparation . 9
10 Procedure . 10
10.1 General . 10
10.2 Calibration . 10
10.3 Validity check of the calibration function . 10
10.4 Measurement . 11
10.4.1 General . 11
10.4.2 Determination . 11
11 Evaluation . 12
12 Expression of results . 13
13 Test report . 13
Annex A (normative) Determination of TOC applying the difference method . 14
Annex B (informative) Performance data for TOC or DOC, and TNb or DNb . 17
Annex C (informative) Alternative detection techniques for TNb and DNb . 19
Bibliography . 20

iv
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
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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/directiveswww.iso.org/directives).).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
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www.iso.org/iso/foreword.htmlwww.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, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 230, Water analysis, in accordance with the Agreement
on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 20236:2018), which has been technically
revised.
The main changes are as follows:
— — the general widening of the method to determine concentrations <1 mg/l of C and N is possible but
dependent on instrument conditions chosen and applying appropriate calibrationhas been expanded;
— — updated list of the normative references have been updated;
— — addition of widening of the method to apply single component standard calibration solutions e.g. based
on as ammonium sulfate or potassium nitrate, toohas been expanded;
— Clause A.5— update of the application insertion of Clause A.5 Test report has been added in order to
reference ofrequire referencing the difference methodmethods with the results report, obligatory;
— — editorially revised.
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.
v
Introduction
Total organic carbon (TOC), dissolved organic carbon (DOC), total bound nitrogen (TNb) and dissolved bound
nitrogen (DNb) are an analytical convention, whose characteristic is a parameter used for water quality
control purposes. These parameters represent the sum of organically bound carbon as well as the sum of
inorganic and organic nitrogen (but not nitrogen gas), which can be dissolved in water or bonded to dissolved
or suspended matter under specified conditions and, if the sample is not filtered, includes that associated with
suspended matter. It does not give information on the nature of the substances. The abbreviations TOC, DOC,
TNb, DNb, TC and TIC refer to values determined by the high temperature method.
Details of a validation interlaboratory trial with the performance data for TOC or DOC and TNb or DNb, all
using the high temperature method in this document, are given in Annex BAnnex B.
vi
Water quality — Determination of total organic carbon (TOC),
dissolved organic carbon (DOC), total bound nitrogen (TNb) and
dissolved bound nitrogen (DNb) after high temperature catalytic
oxidative combustion
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 is applicable for the determination ofspecifies a method to determine the total organic carbon
(TOC), dissolved organic carbon (DOC), total bound nitrogen (TNb) and dissolved bound nitrogen (DNb) in
the form of free ammonia, ammonium, nitrite, nitrate and organic compounds capable of conversion to
nitrogen oxides under thespecific conditions described. .
Cyanide, cyanate and particles of elemental carbon (soot), when present in the sample, can be determined
together with the organic carbon.
Dissolved nitrogen gas (N ) is not determined.
NOTE Generally, the method can be applied for the determination of total carbon (TC) and total inorganic carbon
(TIC), see Annex AAnnex A.
The method is applicable to water samples (e.g. drinking water, raw water, ground water, surface water, sea
water, waste water, leachates).
This document is applicable to determination of TOC and DOC ≥ 1 mg/l and TNb and DNb ≥ 1 mg/l. The upper
working range is restricted by instrument-dependent conditions (e.g. injection volume). Higher
concentrations can be determined after appropriate dilution of the sample. The determination of
concentrations < <1 mg/l is dependent on instrument conditions applying appropriate calibration.
For samples containing volatile organic compounds (e.g. industrial waste water), the application of the
difference method can be considered, see Annex AAnnex A.
The procedure is carried out by automated analysis.
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 8466--1, Water quality — Calibration and evaluation of analytical methods — Part 1: Linear calibration
function
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
total carbon
TC
sum of organically and inorganically bound carbon present in water, including elemental carbon measured
under the conditions of this method
Note 1 to entry: The total carbon is defined as measured under the conditions of the method described in this document.
3.2
total inorganic carbon
TIC
sum of inorganic carbon present in water measured under the conditions of this method
Note 1 to entry: TIC The total inorganic carbon is measured as CO originating only from carbonates, hydrogen
carbonates and dissolved carbon dioxide.
3.3
total organic carbon
TOC
sum of organically bound carbon present in water, bonded to dissolved or suspended matter, including
cyanate, thiocyanate and elemental carbon measured under the conditions of this method
Note
...