SIST EN ISO 18127:2026

SLOVENSKI STANDARD
01-junij-2026
Kakovost vode - Določanje organsko vezanega fluora, klora, broma in joda,
sposobnega adsorpcije (AOF, AOCl, AOBr, AOI) - Metoda z zgorevanjem in ionsko
kromatografijo (ISO 18127:2026)
Water quality - Determination of adsorbable organically bound fluorine, chlorine, bromine
and iodine (AOF, AOCl, AOBr, AOI) - Method using combustion and subsequent ion
chromatographic measurement (ISO 18127:2026)
Wasserbeschaffenheit - Bestimmung von adsorbierbarem organisch gebundenem Fluor,
Chlor, Brom und Iod (AOF, AOCl, AOBr, AOI) - Verfahrens mittels Verbrennung und
nachfolgender Ionenchromatographischer Messung (ISO 18127:2026)
Qualité de l’eau - Dosage des composés organiques adsorbables contenant du fluor, du
chlore, du brome et de l’iode (AOF, AOCl, AOBr, AOI) - Méthode de combustion suivie
d’un mesurage par chromatographie ionique (ISO 18127:2026)
Ta slovenski standard je istoveten z: EN ISO 18127:2026
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 18127
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2026
EUROPÄISCHE NORM
ICS 13.060.50
English Version
Water quality - Determination of adsorbable organically
bound fluorine, chlorine, bromine and iodine (AOF, AOCl,
AOBr, AOI) - Method using combustion and subsequent ion
chromatographic measurement (ISO 18127:2026)
Qualité de l'eau - Dosage des composés organiques Wasserbeschaffenheit - Bestimmung von
adsorbables contenant du fluor, du chlore, du brome et adsorbierbarem organisch gebundenem Fluor, Chlor,
de l'iode (AOF, AOCl, AOBr, AOI) - Méthode de Brom und Iod (AOF, AOCl, AOBr, AOI) - Verfahrens
combustion suivie d'un mesurage par chromatographie mittels Verbrennung und nachfolgender
ionique (ISO 18127:2026) Ionenchromatographischer Messung (ISO 18127:2026)
This European Standard was approved by CEN on 1 December 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18127:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 18127:2026) has been prepared by Technical Committee ISO/TC 147 "Water
quality" in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2026, and conflicting national standards shall
be withdrawn at the latest by August 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 18127:2026 has been approved by CEN as EN ISO 18127:2026 without any modification.

International
Standard
ISO 18127
First edition
Water quality — Determination
2026-02
of adsorbable organically bound
fluorine, chlorine, bromine and
iodine (AOF, AOCl, AOBr, AOI) —
Method using combustion and
subsequent ion chromatographic
measurement
Qualité de l’eau — Dosage des composés organiques adsorbables
contenant du fluor, du chlore, du brome et de l’iode (AOF, AOCl,
AOBr, AOI) — Méthode de combustion suivie d’un mesurage par
chromatographie ionique
Reference number
ISO 18127:2026(en) © ISO 2026
ISO 18127:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 18127:2026(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Interferences . 3
4.1 Interferences during adsorption .3
4.2 Interferences during combustion .3
4.3 Interferences during ion chromatography .3
5 Principle . 3
6 Reagents . 4
7 Apparatus and materials . 8
8 Sampling and sample preparation .11
8.1 General .11
8.2 Sampling for the AOF determination . 12
8.3 Sampling for the AOCl-, AOBr- and AOI determination . 12
8.4 Further procedure of sample preparation . 12
8.4.1 AOF determination . 12
8.4.2 AOCl, AOBr and AOI determination. 12
9 Procedure .12
9.1 Preliminary test . 12
9.2 Homogenization. 13
9.3 Sample preparation . 13
9.3.1 General . 13
9.3.2 Test sample for AOF determination . 13
9.3.3 Test samples for AOCl, AOBr and AOI determination . 13
9.4 Adsorption on activated carbon . 13
9.4.1 Adsorption procedure . 13
9.4.2 Washing of the activated carbon for AOF determination .14
9.4.3 Washing of the activated carbon for AOCl, AOBr and AOI determination .14
9.5 Additional procedure for samples containing suspended solids .14
9.6 Blank determination .14
9.6.1 AOF blank determination .14
9.6.2 AOCl, AOBr and AOI blank determination .14
9.7 Operation of the ion chromatography system . 15
9.7.1 General . 15
9.7.2 Calibration . . . 15
9.7.3 Checking the ion chromatography . 15
9.8 Combustion and absorption . 15
9.9 Measurement of the absorption solution . 15
10 Validation of the overall procedure . .16
10.1 Initial check .16
10.2 Daily check .16
10.3 Test to determine the completeness of the adsorption .16
11 Selection of usable analytical results .16
12 Calculation . 17
13 Expression of the results .18
14 Test report .18

iii
ISO 18127:2026(en)
Annex A (normative) Determination of adsorbable organically bound fluorine (AOF) . 19
Annex B (normative) Determination of adsorbable organically bound chlorine (AOCl) .22
Annex C (normative) Determination of adsorbable organically bound bromine (AOBr) .25
Annex D (normative) Determination of the adsorbable organically bound iodine (AOI) .28
Annex E (informative) Determination of adsorbable organically bound fluorine, chlorine,
bromine and iodine using the shaking procedure (SH-AOF, SH-AOCl, SH-AOBr and SH-
AOI) .31
Annex F (informative) Determination of adsorbable organically bound fluorine, chlorine,
bromine and iodine in waters with high halide contents after solid phase extraction
(SPE-AOF, SPE-AOCl, SPE-AOBr, SPE-AOI) .34
Annex G (normative) Test to determine the completeness of the adsorption by individual
combustion of the activated carbons from the multiple determinations and separate
absorption .37
Annex H (normative) Test to determine the completeness of the adsorption by common
combustion of the activated carbons from different dilution levels .38
Annex I (normative) Test to determine the completeness of the adsorption by adsorption on
columns connected in series with different quantities of adsorption columns .39
Annex J (normative) Calculation of the CIC-AOX from the AOCl, AOBr and AOI results added
(Cl)
according to Annex B, Annex C and Annex D.40
Annex K (informative) Performance data . 41
Bibliography .43

iv
ISO 18127:2026(en)
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 document 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).
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 in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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, 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).
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
ISO 18127:2026(en)
Introduction
Adsorbable organically bound fluorine, chlorine, bromine and iodine are analytical convention parameters
used to monitor water quality. They represent the sum of organically bound fluorine, chlorine, bromine and
iodine that can be adsorbed on activated carbon under specified conditions and, if the sample has not been
filtered, can also be attached to or contained in suspended substances.
In contrast to the adsorbable organically bound halogen (AOX) method according to ISO 9562, this method
can be applied to determine the sum of organofluorine compounds in addition to the determination of the
organically bound chlorine, bromine and iodine and detected halogen-specific separately.
The method is carried out by combustion ion chromatography (CIC).
Procedures for each separate parameter are described in Annex A, Annex B, Annex C and Annex D.
Alternatively, the adsorption of the organic substances contained in the water sample on activated carbon
can also be carried out by the shaking method (see Annex E).
Samples with a high content of suspended solids can be analysed using the shaking method (see Annex E).
Samples with a high content of inorganic halides can be analysed using the solid phase extraction (SPE)
method (see Annex F).
Results for samples analysed according to Annex E (shaking procedure) or Annex F (SPE procedure) can
differ significantly from those of the method specified in the main part.
With some waters, interference can occur that cannot be eliminated. These waters cannot be measured with
the method.
The AOCl, AOBr and AOI results according to Annex B, Annex C and Annex D can also be reported as
adsorbable organically bound halogens determined by combustion ion chromatography (CIC-AOX) (see
Annex J).
vi
International Standard ISO 18127:2026(en)
Water quality — Determination of adsorbable organically
bound fluorine, chlorine, bromine and iodine (AOF, AOCl,
AOBr, AOI) — Method using combustion and subsequent ion
chromatographic measurement
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 organically bound halogens fluorine, chlorine,
bromine and iodine which are adsorbable on activated carbon. Adsorption takes place on activated carbon
packed in columns.
The method is applicable for the determination of:
— ≥ 2 µg/l AOF, expressed as F;
— ≥ 10 µg/l AOCl, expressed as Cl;
— ≥ 1 µg/l AOBr, expressed as Br;
— ≥ 1 µg/l AOI, expressed as I.
The method is applicable for the determination of adsorbable organically bound fluorine, chlorine, bromine
and iodine in water, e.g. in groundwater, surface water, bank filtrate, drinking water, aqueous eluates,
cooling water and wastewater.
The working range is limited by the capacity of the activated carbon, the process blank and the capacity of
the chromatographic separation column. Sample dilution into the working range can be required.
The range of application can be extended to lower concentrations with lower process blanks e.g. using low
blank activated carbons.
The method can also be applied for samples containing suspended solids. Halogens adsorbed on the
suspended solids (e.g. undissolved halides) are also determined. Filtration of the sample prior to analysis
using a membrane filter (0,45 µm) allows the separate determination of dissolved adsorbable and particulate
bound fractions of organically bound fluorine, chlorine, bromine or iodine.
Results from an international interlaboratory trial are presented in Annex K.
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
ISO 18127:2026(en)
ISO 8466-2, Water quality — Calibration and evaluation of analytical methods and estimation of performance
characteristics — Part 2: Calibration strategy for non-linear second-order calibration functions
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
adsorbable organically bound fluorine
AOF
equivalent mass of fluorine in organic halogen compounds, expressed as fluorine, measured under the
conditions of this procedure
3.2
adsorbable organically bound chlorine
AOCl
equivalent mass of chlorine in organic halogen compounds, expressed as chlorine, measured under the
conditions of this procedure
3.3
adsorbable organically bound bromine
AOBr
equivalent mass of bromine in organic halogen compounds, expressed as bromine, measured under the
conditions of this procedure
3.4
adsorbable organically bound iodine
AOI
equivalent mass of iodine in organic halogen compounds, expressed as iodine, measured under the
conditions of this procedure
3.5
adsorbable organically bound halogens
AOX
equivalent mass of the halogens chlorine, bromine and iodine in organic compounds, determined according
to ISO 9562 and expressed as chloride
3.6
test sample
sample obtained from the original sample after preparation and dilution, if necessary, and fed into the
adsorption process
3.7
combustion ion chromatography
CIC
technique comprising oxidative high-temperature combustion followed by absorption of formed hydrogen
halides and subsequent ion chromatographic detection of the halide ions
3.8
adsorbable organically bound halogens, determined by combustion ion chromatography
CIC-AOX
equivalent mass of the halogens chlorine, bromine and iodine in organic compounds, measured under the
conditions of this procedure and expressed as chlorine

ISO 18127:2026(en)
4 Interferences
4.1 Interferences during adsorption
AOF, AOCl, AOBr or AOI values can arise from the presence of inorganic halides in the sample. If the test
sample contains as well as organohalogens in low concentration and inorganic halides in high concentration,
the halides can add significant contribution to the result. These contributions can be dependent on the
matrix and halogenide concentration. It is not possible to specify any information on the concentrations
of inorganic halides at which significant contributions to the result for the AOF, AOCl, AOBr or AOI can be
expected. These can depend on various factors, such as the properties e.g. characteristics of the activated
carbon or contaminated laboratory air. Annex A, Annex B, Annex C and Annex D give examples of halide
concentrations that give significant contributions to the result for the AOF, AOCl, AOBr or AOI.
Sample matrix characteristics [e.g. high concentrations of dissolved organic carbon (DOC)] can cause
interference with the adsorption of the organically bound halogens and result in negative bias. These effects
can be solved by sample dilution or spiking experiments, if necessary. Information on whether the DOC
content of the sample influences the adsorption of AOF, AOCl, AOBr or AOI from the sample can be provided
by current measurements or previous testing of the sampling point. For unfiltered samples, the total organic
carbon (TOC) can also be used as information.
Samples containing living cells (e.g. microorganisms or algae) can cause a positive bias due to their halide
content on AOCl, AOBr and AOI (chloride, bromide and iodide). In this case, the acidified sample should not
be analysed until at least 8 h after sampling.
Particulate inorganic halogen compounds with a melting point < 1 000 °C can cause a positive bias. This can
be avoided by filtering the sample.
High contents of undissolved substances can cause interference with the column method. In these cases, the
use of activated carbon according to 9.4 or the shaking procedure (see Annex E) should be considered.
The recovery of some polar and hydrophilic compounds (e.g. trifluoroacetate or monochloroacetate) or
volatile compounds is incomplete.
Contamination of the laboratory air due to chemicals or other sources can cause positive bias.
4.2 Interferences during combustion
Alkali metals present can cause premature devitrification of a quartz glass combustion tube.
NOTE The use of a ceramic inner tube can increase the lifetime of the combustion tube significantly.
A deficiency or insufficient quantity of water added for hydropyrolysis during AOF determination can lead
to a negative bias.
4.3 Interferences during ion chromatography
Any substance that generates a detector signal similar to that of the analyte ion can cause interference.
Additionally, a high concentration of ions can influence the peak resolution and the retention time of the
analyte. Gradient elution can minimize many of these interferences.
5 Principle
To determine the organically bound halogens, the substances contained in the water sample are adsorbed
onto activated carbon. Enriched halides are displaced from the activated carbon by washing with a nitrate
wash solution. The loaded activated carbon is combusted in an oxygen stream. The resulting hydrogen
halides are sorbed in an absorption solution. The halide ions are then determined by ion chromatography.
The basic requirements for the procedure are:

ISO 18127:2026(en)
— Samples for the determination of AOF are treated differently from samples for the determination of AOCl,
AOBr and AOI.
— Samples for the determination of AOF are not acidified. The adsorption takes place under unchanged pH
conditions. Washing is performed with a neutral washing solution.
— Samples for the determination of AOCl, AOBr and AOI are adjusted to a pH < 2 with nitric acid. The
adsorption and washing step are carried out in a nitric acid environment.
— The aqueous sample is passed through columns of activated carbon which adsorbs the organically bound
halogens.
— The inorganic halides are removed by washing with a nitrate solution.
— The activated carbon is combusted in an oxygen stream at 950 °C or higher. For the determination of AOF,
the loaded activated carbon is combusted with addition of water (hydropyrolysis).
— The resulting change in the volume in the absorption solution is taken into account when calculating the
concentration (e.g. by determining the recovery of an internal standard).
— The hydropyrolytic combustion does not interfere with the determination of AOCl, AOBr and AOI.
— The resulting hydrogen halide ions from the organically bound halogens are collected in an absorption
solution.
The absorption solution is injected into an ion chromatograph with a suppressed conductivity detector
where anions are separated and quantified. The ion chromatographic separation is carried out on an anion
exchange resin as stationary phase. Aqueous solutions of salts of weak monobasic and dibasic acids are used
as eluents for isocratic or gradient elution. Quantification is carried out by means of conductivity detection
(CD). The conductivity of the eluents is reduced by a suppressor device (cation exchanger). UV or tandem UV
detection may be used.
NOTE A UV detector is not required to perform this analysis, but it can be used for bromide and iodide if higher
sensitivity is required or in the case of matrix interference with the CD. UV detection (UVD) can be used in combination
with the CD. The UV detector measures the absorption of the irradiated UV radiation. The measuring wavelength is at
λ = (215 ± 10) nm for bromide and at λ = (226 ± 10) nm for iodide.
The AOCl, AOBr and AOI results according to Annex B, Annex C and Annex D can also be reported as
adsorbable organically bound halogens, determined by combustion ion chromatography CIC-AOX (CIC-
AOX ).
(Cl)
The calculation shall be as described in Annex J.
6 Reagents
6.1 General
Use only reagents with the purity grade “for analyses”, if available. Unless otherwise stated, reagents shall
be weighed to an accuracy of ±1 % of nominal mass. Commercially available solutions of equivalent quality
may be used. If necessary, alternative volumes and concentrations to the solutions described in this clause
may be prepared and used.
All reagents shall be checked for their contribution to the blank, if applicable.
6.2 Water, with a specific electrical resistance of ≥18 MΩ·cm (at 25 °C).
6.3 Reagents for sample stabilization and pre-treatment.
6.3.1 Nitric acid, w(HNO ) = 65 %.
ISO 18127:2026(en)
6.3.2 Sodium sulfite, Na SO .
2 3
6.3.2.1 Sodium sulfite solution, c(Na SO ) = 1 mol/l.
2 3
Dissolve 126 g Na SO (6.3.2) in water (6.2) in a 1 000 ml volumetric flask and dilute to volume with
2 3
water (6.2).
The solution is stable for four weeks if stored at (5 ± 3) °C.
6.3.3 Iodine starch paper.
6.3.4 Potassium iodide.
6.3.5 Starch solution, mass fraction of 1 %.
6.4 Reagents and gases for adsorption, combustion and absorption.
6.4.1 Activated carbon with an iodine number >1 050 mg/g.
Suitable natural coal-derived activated carbons have particle sizes in the range of about 50 µm to 150 µm.
Synthetic materials with larger specific surfaces may also be used.
Various methods can be used to determine the adsorption capacity. One of these methods is described in
[8]
EN 12902 . The iodine number gives an indication of the adsorption capacity of the activated carbon.
NOTE 1 Activated carbon qualities with grain sizes <50 µm can lead to blockage of the adsorption column.
To prevent the activated carbon from being contaminated by adsorption of halogen-containing compounds
from the laboratory air during storage, the activated carbon should be stored in an airtight container (e.g.
aluminium screw bottle, halogen polymer-free plastic bottle or similar). Only the daily required amount for
the intended series or samples should be taken from a separate container. The remainder of the activated
carbon taken from the container each day should be discarded. Any additional activated carbon not used
within the same day shall be discarded.
NOTE 2 The halogen blank values of the activated carbon can be determined by analysing, for example, 100 mg
of the activated carbon analyses moistened with 100 µl water (6.2). The result serves as an indication of relevant
impurities. Ultimately, the analytically decisive factor is the method blank.
The applicability of an activated carbon batch shall be checked on the recoveries of fluorine, chlorine,
bromine or iodine from model substances via the overall procedure given in Annex A, Annex B, Annex C and
Annex D. The compounds listed in Annex A, Annex B, Annex C and Annex D shall be used as test reagents.
6.4.2 Sodium nitrate, NaNO .
6.4.2.1 Neutral nitrate stock solution I, c(NaNO ) = 2 mol/l for AOF determination.
Dissolve 170 g sodium nitrate (6.4.2) in water (6.2) in a 1 000 ml volumetric flask and dilute to volume with
water (6.2).
The solution is stable for six months if stored in an amber glass bottle at ambient temperature.
6.4.2.2 Neutral nitrate wash solution II, c(NaNO ) = 0,01 mol/l for AOF determination.
Pipette 5 ml of neutral nitrate stock solution (6.4.2.1) in a 1 000 ml volumetric flask and dilute to volume
with water (6.2).
The solution is stable for four weeks if stored in an amber glass bottle at ambient temperature.
6.4.2.3 Nitric acid nitrate stock solution I, c(NaNO ) = 2 mol/l for AOCl, AOBr and AOI determination.
ISO 18127:2026(en)
Dissolve 170 g sodium nitrate (6.4.2) in water (6.2) in a 1 000 ml volumetric flask, add 25 ml nitric acid
(6.3.1) and dilute to volume with water (6.2).
The solution is stable for six months if stored in an amber glass bottle at ambient temperature.
6.4.2.4 Nitric acid nitrate wash solution II, c(NaNO ) = 0,01 mol/l, pH ≈ 1,7 for AOCl, AOBr and AOI
determination.
Pipette 5 ml of nitric acid stock solution (6.4.2.3) in a 1 000 ml volumetric flask and dilute to volume with
nitric acid dilution water (6.4.6).
The solution is stable for four weeks if stored in an amber glass bottle at ambient temperature.
6.4.3 Ethanol, C H OH, absolute.
2 5
6.4.4 Standard solutions for testing the overall procedure.
Organic halogen single and multi-component stock solutions with appropriate and required specification
may be used if commercially available. These solutions are stable for six months. The manufacturer
specifications shall be observed. Alternatively, stock solutions may be prepared by weighing. See Annex A,
Annex B, Annex C and Annex D.
6.4.5 Dilution water and blank solution for the determination of the total AOF blank value, 100 ml
water (6.2).
6.4.6 Nitric acid dilution water and blank solution for the determination of the total AOCl, AOBr and
AOI blanks, 100 ml water (6.2), acidified with 0,2 ml nitric acid (6.3.1).
6.4.7 Oxygen, or a mixture of oxygen and inert gas (e.g. argon).
The use of argon is recommended when using adsorption columns packed with cellulose wool. Adsorption
columns packed with ceramic wool or quartz wool can possibly be combusted without the use of an inert
gas. For a residue-free conversion of e.g. cellulose wool packed adsorption columns, an inert gas (e.g. argon)
should be used. Otherwise, incomplete combustion, resulting in incorrect results, can occur.
NOTE Gas purities for oxygen ≥ 99,995 % and argon ≥ 99,998 % have proven to be sufficient.
6.4.8 Absorption solution for combustion gases.
Water (6.2). Alternatively, solutions according to C.4.5 and D.4.5 may be prepared for absorption.
The use of an internal standard in the absorption solution is necessary if the volume of the absorption solution
cannot be determined prior to sample injection into the ion chromatograph. For example, methanesulfonic
acid or phosphate solutions can be used as internal standards (6.5.5).
NOTE The addition of reducing agents, e.g. hydrogen peroxide in an alkaline medium, can be necessary for the
determination of bromine and iodine (see C.4.5 and D.4.5).
6.5 Reagents for the ion chromatography.
6.5.1 Eluents.
Carbonate, hydrogen carbonate, hydroxide salts, e.g. manually, automatically or electrochemically generated
in situ, may be used as eluents. The choice of eluent depends on the selected separation column and detector;
follow the column manufacturer's instructions. The selected combination of separation column and eluent
shall fulfil the requirement for the peak resolution in accordance with 7.8. The eluents may be used as long
as the requirements in 7.8 are fulfilled. An example of a suitable eluent is described in 6.5.2.2.

ISO 18127:2026(en)
Degas the eluents, if necessary. A renewed gas uptake shall be prevented during operation (e.g. by helium
overlay or inline degasser).
6.5.2 Sodium carbonate, Na CO .
2 3
6.5.2.1 Sodium carbonate concentrate, c(Na CO ) = 0,09 mol/l.
2 3
Dissolve 9,54 g sodium carbonate (6.5.2) in water (6.2) in a 1 000 ml volumetric flask and dilute to volume
with water (6.2).
The solution is stable for six months if stored at (5 ± 3) °C.
6.5.2.2 Sodium carbonate eluent, c(Na CO ) = 0,009 mol/l.
2 3
The following eluent is suitable for the determination of the ions mentioned in 6.5.3: pipette 100 ml of the
sodium carbonate concentrate (6.5.2.1) into a 1 000 ml volumetric flask and dilute to volume with water
(6.2).
6.5.3 Fluoride, chloride, bromide and iodide stock solutions, each ρ = 1 000 mg/l.
Single anion and mixed anion stock solutions with adequate and required specifications are commercially
available. These solutions are considered to be stable for several months. Alternatively, prepare stock
solutions manually in accordance with Table 1. The salts are dissolved accordingly in water (6.2) after
adequate drying. Use mixed standard solutions in suitable concentrations with at least five different
concentrations for the calibrations.
Table 1 — Weighing and pre-treatment for stock solutions
a
Anion Salt Weighing in 1 000 ml Drying salt at (105 ± 5) °C for at least
g
Fluoride NaF 2,210 1 h
Chloride NaCl 1,648 2 h
Bromide NaBr 1,288 6 h
Iodide NaI 1,181 3 h
a
Other salts that meet the required specifications may be used.
6.5.4 Fluoride, chloride, bromide and iodide calibration solution.
6.5.4.1 General.
Depending on the expected concentrations, prepare single or mixed standard solutions with fluoride,
chloride, bromide and iodide concentrations from the stock solutions (6.5.3). The example in 6.5.4.2
describes the preparation of mixed standard solutions.
The standard solutions shall be stored in polyethene or glass containers.
6.5.4.2 Example of a fluoride, chloride, bromide and iodide mixed standard solution, each
ρ = 10 mg/l.
Pipette 1,0 ml of each of the stock solutions (6.5.3) into a 100 ml volumetric flask and dilute to volume with
water (6.2).
The solution is stable for one week if stored in glass or polyethene containers at (5 ± 3) °C.
6.5.4.3 Fl
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