Water quality - Determination of dissolved anions by liquid chromatography of ions - Part 4: Determination of chlorate, chloride and chlorite in water with low contamination (ISO 10304-4:2022)

This document specifies a method for the determination of the dissolved anions chlorate, chloride and chlorite in water with low contamination (e.g. drinking water, raw water or swimming pool water).
The diversity of the appropriate and suitable assemblies and the procedural steps depending on them permit a general description only.
For further information on the analytical technique, see Bibliography.

Wasserbeschaffenheit - Bestimmung von gelösten Anionen mittels Ionenchromatographie - Teil 4: Bestimmung von Chlorat, Chlorid und Chlorit in gering belastetem Wasser (ISO 10304-4:2022)

Dieses Dokument legt ein Verfahren zur Bestimmung der gelösten Anionen Chlorat, Chlorid und Chlorit in wenig belasteten Wässern (z. B. Trinkwasser, Rohwasser oder Badewasser) fest.
Wegen der Vielfalt der in Betracht kommenden geeigneten Gerätekomponenten und der davon abhängenden notwendigen Verfahrensschritte können diese nur in allgemeiner Form beschrieben werden.
Weitere Angaben zu dieser Analysentechnik siehe [7].
Durch entsprechende Probenvorbehandlung (z. B. Verdünnung) sind bei Einsatz eines Leitfähigkeits-detektors (LF), eines UV-Detektors (UV) oder eines amperometrischen Detektors (AD) die Anwendungs¬bereiche nach Tabelle 1 zu erzielen.
[Tabelle 1]

Qualité de l'eau - Dosage des anions dissous par chromatographie des ions en phase liquide - Partie 4: Dosage des ions chlorate, chlorure et chlorite dans des eaux faiblement contaminées (ISO 10304-4:2022)

Le présent document prescrit une méthode pour le dosage des anions chlorate, chlorure et chlorite dissous dans les eaux faiblement contaminées (par exemple eau destinée à la consommation humaine, eau brute ou eau de piscine).
La diversité des appareillages appropriés et adaptés et des procédures opératoires qui en découlent ne permet qu'une description globale.
Pour plus d'informations sur la technique analytique, se reporter à la Bibliographie.

Kakovost vode - Določevanje raztopljenih anionov z ionsko tekočinsko kromatografijo - 4. del: Določevanje klorata, klorida in klorita v malo onesnaženih vodah (ISO 10304-4:2022)

General Information

Status
Published
Public Enquiry End Date
01-Mar-2021
Publication Date
15-Jun-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
21-Apr-2022
Due Date
26-Jun-2022
Completion Date
16-Jun-2022

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SLOVENSKI STANDARD
SIST EN ISO 10304-4:2022
01-julij-2022
Nadomešča:
SIST EN ISO 10304-4:2000
Kakovost vode - Določevanje raztopljenih anionov z ionsko tekočinsko

kromatografijo - 4. del: Določevanje klorata, klorida in klorita v malo onesnaženih

vodah (ISO 10304-4:2022)

Water quality - Determination of dissolved anions by liquid chromatography of ions - Part

4: Determination of chlorate, chloride and chlorite in water with low contamination (ISO

10304-4:2022)
Wasserbeschaffenheit - Bestimmung von gelösten Anionen mittels

Ionenchromatographie - Teil 4: Bestimmung von Chlorat, Chlorid und Chlorit in gering

belastetem Wasser (ISO 10304-4:2022)

Qualité de l'eau - Dosage des anions dissous par chromatographie des ions en phase

liquide - Partie 4: Dosage des ions chlorate, chlorure et chlorite dans des eaux
faiblement contaminées (ISO 10304-4:2022)
Ta slovenski standard je istoveten z: EN ISO 10304-4:2022
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
SIST EN ISO 10304-4:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 10304-4:2022
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SIST EN ISO 10304-4:2022
EN ISO 10304-4
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2022
EUROPÄISCHE NORM
ICS 13.060.50 Supersedes EN ISO 10304-4:1999
English Version
Water quality - Determination of dissolved anions by
liquid chromatography of ions - Part 4: Determination of
chlorate, chloride and chlorite in water with low
contamination (ISO 10304-4:2022)

Qualité de l'eau - Dosage des anions dissous par Wasserbeschaffenheit - Bestimmung von gelösten

chromatographie des ions en phase liquide - Partie 4: Anionen mittels Ionenchromatographie - Teil 4:

Dosage des ions chlorate, chlorure et chlorite dans des Bestimmung von Chlorat, Chlorid und Chlorit in gering

eaux faiblement contaminées (ISO 10304-4:2022) belastetem Wasser (ISO 10304-4:2022)

This European Standard was approved by CEN on 8 January 2022.

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, Turkey 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

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10304-4:2022 E

worldwide for CEN national Members.
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SIST EN ISO 10304-4:2022
EN ISO 10304-4:2022 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 10304-4:2022
EN ISO 10304-4:2022 (E)
European foreword

This document (EN ISO 10304-4:2022) 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 September 2022, and conflicting national standards

shall be withdrawn at the latest by September 2022.

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 supersedes EN ISO 10304-4:1999.

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, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 10304-4:2022 has been approved by CEN as EN ISO 10304-4:2022 without any

modification.
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SIST EN ISO 10304-4:2022
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SIST EN ISO 10304-4:2022
INTERNATIONAL ISO
STANDARD 10304-4
Second edition
2022-03
Water quality — Determination
of dissolved anions by liquid
chromatography of ions —
Part 4:
Determination of chlorate, chloride
and chlorite in water with low
contamination
Qualité de l'eau — Dosage des anions dissous par chromatographie
des ions en phase liquide —
Partie 4: Dosage des ions chlorate, chlorure et chlorite dans des eaux
faiblement contaminées
Reference number
ISO 10304-4:2022(E)
© ISO 2022
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SIST EN ISO 10304-4:2022
ISO 10304-4:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO 2022 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 10304-4:2022
ISO 10304-4:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 2

4 Interferences ............................................................................................................................................................................................................ 2

5 Principle ........................................................................................................................................................................................................................ 2

6 Reagents ........................................................................................................................................................................................................................ 3

7 Apparatus .................................................................................................................................................................................................................... 6

8 Quality requirements for the separator column ............................................................................................................... 6

9 Sampling and sample pre-treatment .............................................................................................................................................8

9.1 General requirements ...................................................................................................................................................................... 8

9.2 Sample pre-treatment in the case of elevated levels of chloride and bromide .............................. 9

10 Procedure ....................................................................................................................................................................................................................9

10.1 General ........................................................................................................................................................................................................... 9

10.2 Calibration .................................................................................................................................................................................................. 9

10.3 Measurement of samples using the standard calibration procedure ................................................. 10

10.4 Validity check of the calibration function ................................................................................................................... 10

11 Calculation ...............................................................................................................................................................................................................10

12 Expression of results ....................................................................................................................................................................................10

13 Test report ...............................................................................................................................................................................................................10

Annex A (informative) Performance data ...................................................................................................................................................12

Bibliography .............................................................................................................................................................................................................................15

iii
© ISO 2022 – All rights reserved
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SIST EN ISO 10304-4:2022
ISO 10304-4:2022(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, 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 10304-4:1997), which has been

technically revised. The main changes compared to the previous edition are as follows:

— in the introduction, all requirements concerning the application of the method have been deleted

and moved to other clauses;

— in Clause 2, all the references made but withdrawn since the publication of the 1997 edition (e.g.

ISO 10304-2) have been deleted and the references ISO 5667-1 and ISO 5667-3 have been moved to

the Bibliography;
— in 6.8, various eluent formulations have been reduced to one example;

— in Clause 8, the calculation procedure for the peak resolution according to the USP definition

[Formula (1)] has been completed with the EP definition [Formula (2)] (both calculations are

equivalent);

— in 9.1, information that drinking water disinfection treatment using chlorine dioxide can cause the

formation of chlorite and chlorate (paragraph 2) and helpful precautions to minimize/eliminate

such formation (paragraph 3) have been added;

— in Clause 11, the option to report result concentrations in microgram per litre has been added.

A list of all parts in the ISO 10304 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.
© ISO 2022 – All rights reserved
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SIST EN ISO 10304-4:2022
INTERNATIONAL STANDARD ISO 10304-4:2022(E)
Water quality — Determination of dissolved anions by
liquid chromatography of ions —
Part 4:
Determination of chlorate, chloride and chlorite in water
with low contamination

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 the dissolved anions chlorate, chloride and

chlorite in water with low contamination (e.g. drinking water, raw water or swimming pool water).

The diversity of the appropriate and suitable assemblies and the procedural steps depending on them

permit a general description only.
For further information on the analytical technique, see Bibliography.

An appropriate pre-treatment of the sample (e.g. dilution) and the use of a conductivity detector (CD),

UV detector (UV) or amperometric detector (AD) make the working ranges given in Table 1 feasible.

Table 1 — Working ranges of the analytical method
Anion Working range Detection
mg/l
Chlorate 0,03 to 10 CD
Chloride 0,1 to 50 CD
0,05 to 1 CD
Chlorite 0,1 to 1 UV; λ = 207 nm to 220 nm
0,01 to 1 AD; 0,4 V to 1,0 V

The working range is restricted by the ion-exchange capacity of the columns. If necessary, samples can be adjusted to

this range by dilution.

The minimum working range for chlorite of 0,05 mg/l was obtained using calibration checks, but the interlaboratory

trials (see Table A.4) showed that it is difficult to obtain this with sufficient accuracy, and only if taking great care.

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 2022 – All rights reserved
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SIST EN ISO 10304-4:2022
ISO 10304-4:2022(E)
3 Terms and definitions
No terms and definitions are listed in this document.

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/
4 Interferences

Organic acids such as mono- and dicarboxylic acids or disinfection by-products (e.g. chloroacetic acid)

can interfere.

Dissolved organics can react with the working electrode of the amperometric detector, causing a

decrease in sensitivity.

The presence of fluoride, carbonate, nitrite and nitrate can cause interference with the determination

of chlorate, chloride and chlorite. The respective concentrations given in Table 2 are typical for

conductivity, UV and amperometric detectors.

Elevated loads of chloride and bromide can cause interference with the determination of chlorite and

chlorate. Remove chloride and bromide with the aid of special exchangers (9.2).

Solid particles and organic compounds (such as mineral oils, detergents and humic acids) shorten

the lifetime of the separator column. They are therefore eliminated from the sample prior to analysis

(Clause 9).
Table 2 — Typical cross-sensitivity of anions
Relation of the mass concentration of
Detection method
measured ion interfering ion
1 part chlorate 50 parts bromide CD
1 part chlorate 500 parts nitrate CD
1 part chloride 500 parts fluoride CD
1 part chloride 1 000 parts chlorite CD
1 part chloride 50 parts nitrite CD
1 part chlorite 100 parts fluoride CD
1 part chlorite 10 parts fluoride UV
1 part chlorite 1 000 parts carbonate CD
1 part chlorite 1 000 parts chloride CD / UV / AD
1 part chlorite 100 parts nitrite AD

In case the quality requirements in Clause 8 (e.g. see Figures 2 and 3) are not achieved, the sample shall be diluted.

5 Principle

Liquid chromatographic separation of chlorate, chloride and chlorite is carried out by means of a

separator column. A low-capacity anion exchanger is used as the stationary phase and usually aqueous

solutions of salts of weak mono- and dibasic acids as mobile phases (eluent, 6.8).

Detection is by CD with or without suppressor device, UV or AD.

When using conductivity detectors, it is essential that the eluents have a sufficiently low conductivity.

For this reason, conductivity detectors are often combined with a suppressor device (cation exchangers)

© ISO 2022 – All rights reserved
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SIST EN ISO 10304-4:2022
ISO 10304-4:2022(E)

which reduces the conductivity of the eluent and transforms the sample species into their respective

acids.
UV detection measures the absorption directly or indirectly.

Amperometric detection of chlorite is carried out via measurement of the current generated by the

oxidation of chlorite. The oxidation voltage for chlorite depends on the pH of the eluent. The use of

carbon electrodes has proved successful.

The concentration of the respective anions is determined by a calibration of the overall procedure.

Particular cases may require calibration by means of standard addition (spiking). Control experiments

are necessary to check the validity of the calibration function. Replicate determinations can be

necessary.
6 Reagents

Use only reagents of recognized analytical grade. Carry out weighing with an accuracy of 1 % of the

nominal mass. An increase in electrical conductivity due to an uptake of carbon dioxide does not

interfere with the determination. Use and prepare alternative concentrations or volumes of solutions

as described below, if necessary. Alternatively, use commercially available solutions of the required

specification.
6.1 Water.

The water used shall have a resistivity ≥18 MΩ·cm (25 °C) and shall not contain particulate matter of a

particle size >0,45 µm.
6.2 Sodium hydrogencarbonate, NaHCO .
6.3 Sodium carbonate, Na CO .
2 3
6.4 Sodium hydroxide solution, c(NaOH) = 0,1 mol/l.
6.5 Sodium chlorite, NaClO (80 %).
6.6 Sodium chloride, NaCl.
6.7 Sodium chlorate, NaClO .
6.8 Eluents.

Degas all eluents used. Take steps to avoid any renewed air pick up during operation (e.g. by helium

sparging, inline degasser).

The choice of eluent (e.g. based on sodium carbonate or sodium hydroxide solutions, potassium

hydroxide, mixed with organic modifiers, if needed) depends on the choice of column and detector;

seek advice from the column supplier. Apply eluents that were prepared: manually, by inline dilution or

electrochemically in situ. The chosen combination of separator column and eluent shall conform to the

resolution requirements stated in Clause 7. Use eluents as long as the requirement in Clause 8 is met.

An example for an appropriate eluent manually prepared is given in 6.8.2.
© ISO 2022 – All rights reserved
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SIST EN ISO 10304-4:2022
ISO 10304-4:2022(E)
6.8.1 Sodium carbonate/sodium hydrogencarbonate concentrate.
For the eluent concentrate preparation:

— Place 19,1 g of sodium carbonate (6.3) and 14,3 g of sodium hydrogencarbonate (6.2) into a volumetric

flask of nominal capacity 1 000 ml, dissolve in water (6.1) and dilute to volume with water (6.1).

— The solution contains 0,18 mol/l of sodium carbonate and 0,17 mol/l of sodium hydrogencarbonate.

This solution is stable for several months if stored at 2 °C to 6 °C.
6.8.2 Sodium carbonate/sodium hydrogencarbonate eluent.

The following eluent is applicable for the determination of chlorate, chloride and chlorite:

— Pipette 50 ml of the sodium carbonate/sodium hydrogencarbonate concentrate (6.8.1) into a

volumetric flask of nominal capacity 5 000 ml and dilute to volume with water (6.1).

— The solution contains 0,001 8 mol/l of sodium carbonate and 0,001 7 mol/l of sodium

hydrogencarbonate. Store the solution in amber-coloured glass and renew it every 3 d.

6.9 Stock solutions.

Prepare stock solutions of concentration ρ = 1 000 mg/l for each of the anions chlorate, chloride and

chlorite.

Dissolve the appropriate mass of each of the substances (6.5, 6.6 and 6.7), prepared as stated in Table 3,

in approximately 800 ml of water (6.1, degassed with nitrogen or helium), in volumetric flasks of

nominal capacity 1 000 ml, add 1 ml of sodium hydroxide solution (6.4). Dilute the volume with water

(6.1). The solutions are stable as indicated in Table 3.

Alternatively, use commercially available stock solutions of the required concentration.

Table 3 — Mass of portion, pre-treatment and storage suggestions for stock solutions

Anion Compound Concentration derived Pre-treatment Storage
from substance-portion
g/l
In glass for one month if kept
Chlorate NaClO 1,275 3 ± 0,013 Dry in a desiccator only
at 2 °C to 6 °C
In polyethylene for three
Chloride NaCl 1,648 4 ± 0,017 Dry at 105 °C
months if kept at 2 °C to 6 °C
In glass for one week if kept
Chlorite NaClO ≈1,7 Dry in a desiccator only
at 2 °C to 6 °C in the dark

The concentration of the chlorite stock solution shall be determined iodometrically before use (see ISO 10530).

6.10 Standard solutions.

Depending upon the concentrations expected, prepare standard solutions of different anion

composition and concentration from the stock solutions (6.9). The risk of changes in concentration

caused by interaction with the flask material increases with decreasing anion concentration. Store the

standard solutions in polyethylene (PE) flasks. Take into account that sodium chlorite salt can contain

up to 20 % sodium chloride. Prepare chlorite standard solutions as described in 6.10.2 to avoid chloride

contamination, for example, of the mixed standard solution (6.10.1).
© ISO 2022 – All rights reserved
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SIST EN ISO 10304-4:2022
ISO 10304-4:2022(E)
6.10.1 Mixed standard solution of chlorate and chloride.
The mass concentrations of this solution are as follows:
ρ =10mg/l
ClOC, l

Pipette 1 ml of each of the chlorate and chloride stock solutions (6.9) into a volumetric flask of nominal

capacity 100 ml, add 0,1 ml of sodium hydroxide solution (6.4) and fill up to volume with water (6.1).

Prepare the solution on the day of use.

Other mixed standard solutions can be made by respective dilutions of the mixed standard solution.

6.10.2 Chlorite standard solution.
The mass concentration of this solution is as follows:
ρ =10mg/l
ClO

Pipette 1 ml of chlorite stock solution (6.9) into a volumetric flask of nominal capacity 100 ml, add

0,1 ml of sodium hydroxide solution (6.4) and make up to volume with water (6.1).

Prepare the solution on the day of use.

Other standard solutions can be made by respective dilutions of the chlorite standard solution.

6.11 Anion calibration solutions.
6.11.1 Chlorate, chloride calibration solutions.

Depending on the anion concentration expected, use the stock solutions (6.9) or the mixed standard

solution (6.10.1) to prepare 5 to 10 calibration solutions distributed over the expected working range as

evenly as possible.
− −
For example, proceed as follow for the range 0,1 mg/l to 1,0 mg/l of ClO , Cl .

Into a series of volumetric flasks of nominal capacity 100 ml, pipette a volume of 1 ml, 2 ml, 3 ml, 4 ml,

5 ml, 6 ml, 7 ml, 8 ml, 9 ml, and 10 ml of the mixed standard solution (6.10.1), add 0,1 ml of sodium

− −

hydroxide solution (6.4) and dilute to volume with water (6.1). The concentrations of ClO and Cl in

these calibration solutions are 0,1 mg/l, 0,2 mg/l, 0,3 mg/l, 0,4 mg/l, 0,5 mg/l, 0,6 mg/l, 0,7 mg/l,

0,8 mg/l, 0,9 mg/l and 1,0 mg/l, respectively.
Prepare the calibration solutions on the day of use.
6.11.2 Chlorite calibration solutions.

Depending on the anion concentration expected, use the stock solution (6.9) or the chlorite standard

solution (6.10.2) to prepare 5 to 10 calibration solutions distributed over the expected working range

as evenly as possible.
For example, proceed as follows for the range 0,1 mg/l to 1,0 mg/l ClO ⎺.

Into a series of volumetric flasks of nominal capacity 100 ml, pipette a volume of 1 ml, 2 ml, 3 ml, 4 ml,

5 ml, 6 ml, 7 ml, 8 ml, 9 ml, and 10 ml of the chlorite standard solution (6.10.2), add 0,1 ml of sodium

hydroxide solution (6.4) and dilute to volume with water (6.1). The concentrations of ClO ⎺ in these

calibration solutions are 0,1 mg/l, 0,2 mg/l, 0,3 mg/l, 0,4 mg/l, 0,5 mg/l, 0,6 mg/l, 0,7 mg/l, 0,8 mg/l,

0,9 mg/l and 1,0 mg/l respectively.
Prepare the calibration solutions on the day of use.
© ISO 2022 – All rights reserved
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SIST EN ISO 10304-4:2022
ISO 10304-4:2022(E)
6.12 Blank solution.

Fill a volumetric flask of nominal capacity 100 ml up to volume with water (6.1) and add 0,1 ml of

sodium hydroxide solution (6.4).
7 Apparatus

Usual laboratory apparatus, and, the following in particular an ion chromatographic system, complying

with the quality requirements of Clause 8. In general, it shall consist of the following components (see

Figure 1):
a) eluent reservoir;
b) pump, suitable for HPLC;

c) sample injection system incorporating a sample loop (e.g. sample loop of volume 50 µl);

d) precolumn (see 10.3), for example, containing the same resin material as the analytical separator

column or those being packed with a macroporous polymer;
e) separator column with the specified separating performance (Clause 8);

f) conductivity detector (with or without a suppressor device assembly) or UV detector (e.g. spectral

photometer; 190 nm to 400 nm) or amperometric detector;
g) recording device (e.g. recorder, integrator with printer);

h) cartridges or columns with non-polar phases to be used for sample preparation (e.g.

polyvinylpyrrolidone or RP C18 cartridges; see 9.1); the use of RP C18 material is restricted by

the pH of the eluent, thus, only RP C18 cartridges should be used, and not columns;

i) cation exchanger in the Ag form (cartridge, 9.2);
j) cation exchanger in the H form (cartridge, 9.2).
Figure 1 — Sch
...

SLOVENSKI STANDARD
oSIST prEN ISO 10304-4:2021
01-februar-2021
Kakovost vode - Določevanje raztopljenih anionov z ionsko tekočinsko

kromatografijo - 4. del: Določevanje klorata, klorida in klorita v malo onesnaženih

vodah (ISO/DIS 10304-4:2020)

Water quality - Determination of dissolved anions by liquid chromatography of ions - Part

4: Determination of chlorate, chloride and chlorite in water with low contamination

(ISO/DIS 10304-4:2020)

Qualité de l'eau - Dosage des anions dissous par chromatographie des ions en phase

liquide - Partie 4: Dosage des ions chlorate, chlorure et chlorite dans des eaux
faiblement contaminées (ISO/DIS 10304-4:2020)
Ta slovenski standard je istoveten z: prEN ISO 10304-4
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
oSIST prEN ISO 10304-4:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 10304-4:2021
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oSIST prEN ISO 10304-4:2021
DRAFT INTERNATIONAL STANDARD
ISO/DIS 10304-4
ISO/TC 147/SC 2 Secretariat: DIN
Voting begins on: Voting terminates on:
2020-12-28 2021-03-22
Water quality — Determination of dissolved anions by
liquid chromatography of ions —
Part 4:
Determination of chlorate, chloride and chlorite in water
with low contamination

Qualité de l'eau — Dosage des anions dissous par chromatographie des ions en phase liquide —

Partie 4: Dosage des ions chlorate, chlorure et chlorite dans des eaux faiblement contaminées

ICS: 13.060.50
THIS DOCUMENT IS A DRAFT CIRCULATED
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FOR COMMENT AND APPROVAL. IT IS
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STANDARD UNTIL PUBLISHED AS SUCH.
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NATIONAL REGULATIONS.
ISO/DIS 10304-4:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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oSIST prEN ISO 10304-4:2021
ISO/DIS 10304-4:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 10304-4:2021
ISO/DIS 10304-4:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Interferences ............................................................................................................................................................................................................ 2

5 Principle ........................................................................................................................................................................................................................ 2

6 Reagents ........................................................................................................................................................................................................................ 3

7 Apparatus ..................................................................................................................................................................................................................... 5

8 Quality requirements for the separator column ................................................................................................................. 6

9 Sampling and sample pretreatment ................................................................................................................................................ 8

9.1 General requirements ....................................................................................................................................................................... 8

9.2 Sample pretreatment in the case of elevated levels of chloride and bromide ................................. 9

10 Procedure..................................................................................................................................................................................................................... 9

10.1 Calibration .................................................................................................................................................................................................. 9

10.2 Measurement of samples using the standard calibration procedure ...................................................10

10.3 Validity check of the calibration function .....................................................................................................................10

11 Calculation ...............................................................................................................................................................................................................11

12 Expression of results .....................................................................................................................................................................................11

13 Test report ................................................................................................................................................................................................................11

Annex A (informative) Performance data ....................................................................................................................................................12

Bibliography .............................................................................................................................................................................................................................15

© ISO 2020 – All rights reserved iii
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oSIST prEN ISO 10304-4:2021
ISO/DIS 10304-4:2020(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.

This second edition cancels and replaces the first edition (ISO 10304-4:1997), which has been

technically revised.
The main changes compared to the previous edition are as follows:

— General: Use of basic text modules and adaption of the structure of the method based on the current

layout of ISO/TC 147 standards. None of the amendments do influence e.g. the scope and the quality

of the analytical results.

— Introduction: Deletion of all requirements concerning the application of the method and moving of

all of the wording needed to other clauses.

— Clause 2: Deletion of all references made but withdrawn since the publication of the 1997 edition

(e.g. ISO 10304-2). All references made to the ISO 5667 series have been moved to Bibliography.

— 6.8: Various eluent formulations have been reduced to one example.

— Clause 8: The calculation procedure for the peak resolution according to the USP definition

(Formula 1) has been completed with the EP definition (Formula 2). Both calculations are equivalent.

— 9.1: Information that drinking water disinfection treatment using chlorine dioxide can cause the

formation of chlorite and chlorate (paragraph 2) and helpful precautions to minimize/elimination

such formation (paragraph 3) have been added.

— Clause 11: The option to report result concentrations in microgram per litre has been added.

A list of all parts in the ISO 10304 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.
iv © ISO 2020 – All rights reserved
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Introduction

The diversity of the appropriate and suitable assemblies and the procedural steps depending on them

permit a general description only.
For further information on the analytical technique see Reference [4].
© ISO 2020 – All rights reserved v
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oSIST prEN ISO 10304-4:2021
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oSIST prEN ISO 10304-4:2021
DRAFT INTERNATIONAL STANDARD ISO/DIS 10304-4:2020(E)
Water quality — Determination of dissolved anions by
liquid chromatography of ions —
Part 4:
Determination of chlorate, chloride and chlorite in water
with low contamination
1 Scope

This document specifies a method for the determination of the dissolved anions chlorate, chloride, and

chlorite in water with low contamination (e.g. drinking water, raw water or swimming pool water).

An appropriate pretreatment of the sample (e.g. dilution) and the use of a conductivity detector (CD),

UV detector (UV) or amperometric detector (AD) make the working ranges given in Table 1 feasible.

Table 1 — Working ranges of the analytical method
Anion Working range Detection
mg/l
Chlorate 0,03 to 10 CD
Chloride 0,1 to 50 CD
Chlorite 0,05 to 1 CD
0,1 to 1 UV; λ=207 nm to 220 nm
0,01 to 1 AD; 0,4 to 1,0 V

The working range is restricted by the ion-exchange capacity of the columns. Dilute the sample in to the working range,

if necessary.

The minimum working range for chlorite of 0,05 mg/l was obtained using calibration checks, but the round robin trials

(Annex A, Table A.4) showed that it is difficult to obtain this with sufficient accuracy. Thus great care shall be taken when

working in the lower range of this method.
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 and estimation of

performance characteristics — Part 1: Statistical evaluation of the linear calibration function

ISO 10304-1, Water quality — Determination of dissolved anions by liquid chromatography of ions —

Part 1: Determination of bromide, chloride, fluoride, nitrate, nitrite, phosphate and sulfate

ISO 10304-3, Water quality — Determination of dissolved anions by liquid chromatography of ions —

Part 3: Determination of chromate, iodide, sulfite, thiocyanate and thiosulfate

ISO 10530, Water quality — Determination of dissolved sulfide — Photometric method using methylene blue

3 Terms and definitions
No terms and definitions are listed in this document.
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oSIST prEN ISO 10304-4:2021
ISO/DIS 10304-4:2020(E)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org ./ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Interferences

Organic acids such as mono- and dicarboxylic acids or disinfection byproducts (e.g. chloroacetic acid)

can interfere.

Dissolved organics can react with the working electrode of the amperometric detector, causing a

decrease in sensitivity.

The presence of fluoride, carbonate, nitrite and nitrate can cause interference with the determination

of chlorate, chloride and chlorite. The respective concentrations given in Table 2 are typical for

conductivity, UV and amperometric detectors.

Elevated loads of chloride and bromide can cause interference with the determination of chlorite and

chlorate. Remove chloride and bromide with the aid of special exchangers (9.2).

Solid particles and organic compounds (such as mineral oils, detergents, and humic acids) shorten the

life-time of the separator column. They are therefore eliminated from the sample prior to analysis

(Clause 9).
Table 2 — Typical cross-sensitivity of anions

Relation of the mass concentration of measured ion/interfering ion Detection method

1 part chlorate / 50 parts bromide CD
1 part chlorate / 500 parts nitrate CD
1 part chloride / 500 parts fluoride CD
1 part chloride / 1 000 parts chlorite CD
1 part chloride / 50 parts nitrite CD
1 part chlorite / 100 parts fluoride CD
1 part chlorite / 10 parts fluoride UV
1 part chlorite / 1 000 parts carbonate CD
1 part chlorite / 1 000 parts chloride CD / UV / AD
1 part chlorite / 100 parts nitrite AD

In case the quality requirements in Clause 8 (e.g. see Figures 2 and 3) are not achieved, the sample shall be diluted.

5 Principle

Liquid chromatographic separation of chlorate, chloride, and chlorite is carried out by means of a

separator column. A low-capacity anion exchanger is used as the stationary phase, and usually aqueous

solutions of salts of weak mono- and dibasic acids as mobile phases (eluent, 6.8).

Detection is by conductivity (CD) with or without suppressor device, UV or amperometric detector (AD).

When using conductivity detectors it is essential that the eluents have a sufficiently low conductivity.

For this reason, conductivity detectors are often combined with a suppressor device (cation

exchangers) which will reduce the conductivity of the eluent and transform the sample species into

their respective acids.
UV detection measures the absorption directly or indirectly.
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Amperometric detection of chlorite is carried out via measurement of the current generated by the

oxidation of chlorite. The oxidation voltage for chlorite depends on the pH of the eluent. The use of

carbon electrodes has proved successful.

The concentration of the respective anions is determined by a calibration of the overall procedure.

Particular cases may require calibration by means of standard addition (spiking). Control experiments

are necessary to check the validity of the calibration function. Replicate determinations can be

necessary.
6 Reagents

Use only reagents of recognized analytical grade. Carry out weighing with an accuracy of 1 % of the

nominal mass. An increase in electrical conductivity due to an uptake of carbon dioxide does not

interfere with the determination. Use and prepare alternative concentrations or volumes of solutions

as described below, if necessary. Alternatively, use commercially available solutions of the required

specification.
6.1 Water

The water shall have a resistivity of ≥18 MΩ cm (25 °C) and shall not contain particulate matter of a

particle size > 0,45 µm.
6.2 Sodium hydrogencarbonate, NaHCO .
6.3 Sodium carbonate, Na CO .
2 3
6.4 Sodium hydroxide solution, c(NaOH) = 0,1 mol/l.
6.5 Sodium chlorite, NaClO (80 %).
6.6 Sodium chloride, NaCl.
6.7 Sodium chlorate, NaClO .
6.8 Eluents

Degas all eluents used. Take steps to avoid any renewed air pick up during operation (e.g. by helium

sparging, inline degasser).

The choice of eluent (e.g. based on sodium carbonate or sodium hydroxide solutions, potassium

hydroxide, mixed with organic modifiers, if needed) depends on the choice of column and detector;

seek advice from the column supplier. Apply eluents that were prepared: manually, by inline dilution or

electrochemically in situ. The chosen combination of separator column and eluent shall conform to the

resolution requirements stated in 7.1. Use eluents as long as the requirement in Clause 8 is met.

An example for an appropriate eluent manually prepared is given in 6.8.2.
6.8.1 Sodium carbonate/sodium hydrogencarbonate concentrate
For the eluent concentrate preparation:

Place 19,1 g of sodium carbonate (6.3) and 14,3 g of sodium hydrogencarbonate (6.2) into a volumetric

flask of nominal capacity 1 000 ml, dissolve in water (6.1) and dilute to volume with water (6.1).

The solution contains 0,18 mol/l of sodium carbonate and 0,17 mol/l of sodium hydrogencarbonate.

This solution is stable for several months if stored at 2 °C to 6 °C.
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6.8.2 Sodium carbonate/sodium hydrogencarbonate eluent

The following eluent is applicable for the determination of chlorate, chloride and chlorite:

Pipette 50 ml of the sodium carbonate/sodium hydrogencarbonate concentrate (6.8.1) into a volumetric

flask of nominal capacity 5 000 ml and dilute to volume with water (6.1).

The solution contains 0,001 8 mol/l of sodium carbonate and 0,001 7 mol/l of sodium hydrogencarbonate.

Store the solution in amber-coloured glass and renew it every 3 d.
6.9 Stock solutions

Prepare stock solutions of concentration ρ = 1 000 mg/l for each of the anions chlorate, chloride and

chlorite.

Dissolve the appropriate mass of each of the substances (6.5, 6.6, 6.7), prepared as stated in Table 3, in

approximately 800 ml of water (6.1, degassed with nitrogen or helium), in volumetric flasks of nominal

capacity 1 000 ml, add 1 ml of sodium hydroxide solution (6.4). Dilute to volume with water (6.1). The

solutions are stable as indicated in Table 3.

Alternatively, use commercially available stock solutions of the required concentration.

Table 3 — Mass of portion, pretreatment and storage suggestions for stock solutions

Anion Compound Concentration derived Pretreatment Storage
from substance-portion
g/l

Chlorate NaClO 1,275 3 ± 0,013 Dry in a desiccator only! In glass for one month if

kept at 2 °C to 6 °C
Chloride NaCl 1,648 4 ± 0,017 Dry at 105 °C In polyethylene for three
months if kept at 2 °C to
6 °C
Chlorite NaClO approx. 1,7 Dry in a desiccator only! In glass for one week if
kept at 2 °C to 6 °C in the
dark

The concentration of the chlorite stock solution shall be determined iodometrically before use (see ISO 10530,

Annex A).
6.10 Standard solutions

Depending upon the concentrations expected, prepare standard solutions of different anion

composition and concentration from the stock solutions (6.9). The risk of changes in concentration

caused by interaction with the flask
...

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