SIST EN ISO 10304-4:2000

SLOVENSKI STANDARD
SIST EN ISO 10304-4:2000
01-januar-2000
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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
10304-4:1997)
Wasserbeschaffenheit - Bestimmung von gelösten Anionen mittels
Ionenchromatographie - Teil 4: Bestimmung von Chlorat, Chlorid und Chlorit in gering
belastetem Wasser (ISO 10304-4:1997)
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 10304-4:1997)
Ta slovenski standard je istoveten z: EN ISO 10304-4:1999
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
SIST EN ISO 10304-4:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 10304-4:2000

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SIST EN ISO 10304-4:2000

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SIST EN ISO 10304-4:2000

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SIST EN ISO 10304-4:2000

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SIST EN ISO 10304-4:2000
INTERNATIONAL ISO
STANDARD 10304-4
First edition
1997-12-15
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
AA
Reference number
ISO 10304-4:1997(E)

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SIST EN ISO 10304-4:2000
ISO 10304-4:1997(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.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 10304-4 was prepared by Technical Committee ISO/TC 147, Water quality,
Subcommittee SC 2, Physical, chemical and biochemical methods.
ISO 10304 consists of the following parts, under the general title Water quality — Determination of dissolved anions
by liquid chromatography of ions:
— Part 1: Determination of fluoride, chloride, bromide, nitrate, nitrite, orthophosphate and sulfate in water with low
contamination
— Part 2: Determination of bromide, chloride, nitrate, nitrite, orthophosphate and sulfate in waste water
— Part 3: Determination of chromate, iodide, sulfite, thiocyanate and thiosulfate
— Part 4: Determination of chlorate, chloride and chlorite in water with low contamination.
Annexes A and B of this part of ISO 10304 are for information only.
©  ISO 1997
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet central@iso.ch
X.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
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ISO
ISO 10304-4:1997(E)
Introduction
The essential minimum requirements of an ion chromatographic system applied within the scope of this part of ISO
10304 are the following:
- Resolution power of the column: For the anion to be determined it is essential that
the peak resolution does not fall below R = 1,3
(clause 7, figure 3)
- Method of detection: a) Measurement of the electrical conductivity with
or without suppressor device
b) Spectrometric measurement (UV/VIS), directly
or indirectly
c) Amperometric direct detection
- Applicability of the method: Working ranges according to table 1
- Calibration (9.1): Calibration and determination of the linear working
range (see ISO 8466-1). Use of the method of
standard addition to special cases of application
(9.2).
- Guaranteeing the analytical quality (9.3): Validity check of the calibration function. Replicate
determinations, if necessary.
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 [2].
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SIST EN ISO 10304-4:2000

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SIST EN ISO 10304-4:2000
©
INTERNATIONAL STANDARD   ISO ISO 10304-4:1997(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 part of ISO 10304 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 standards contain provisions which, through reference in this text, constitute provisions of this part of
ISO 10304. At the time of publication, the editions indicated were valid. All standards are subject to revision, and
parties to agreements based on this part of ISO 10304 are encouraged to investigate the possibility of applying the
most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid
International Standards.
ISO 5667-1:1980
Water quality - Sampling - Part 1: Guidance on the design of sampling programmes.
ISO 5667-2:1991 Water quality - Sampling - Part 2: Guidance on sampling techniques.
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SIST EN ISO 10304-4:2000
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ISO 10304-4:1997(E)
ISO 5667-3:1994 Water quality - Sampling - Part 3: Guidance on the preservation and handling of
samples.
ISO 8466-1:1990 Water quality - Calibration and evaluation of analytical methods and estimation of
performance characteristics - Part 1: Statistical evaluation of the linear calibration
function.
ISO 10304-1:1992 Water quality - Determination of dissolved anions by liquid chromatography of ions -
Part 1: Determination of fluoride, chloride, bromide, nitrate, nitrite, orthophosphate
and sulfate in water with low contamination
ISO 10304-2:1995 Water quality - Determination of dissolved anions by liquid chromatography of ions -
Part 2: Determination of bromide, chloride, nitrate, nitrite, orthophosphate and sulfate
in waste water
ISO 10304-3:1997 Water quality - Determination of dissolved anions by liquid chromatography of ions -
Part 3: Determination of chromate, iodide, sulfite, thiocyanate and thiosulfate
ISO 10530: 1992 Water quality - Determination of dissolved sulfide - Photometric method using
methylene blue.
3 Interferences
3.1  Organic acids such as mono- and dicarboxylic acids or disinfection byproducts (e.g. chloroacetic acid) can
interfere.
3.2  Dissolved organics can react with the working electrode of the amperometric detector, causing a decrease in
sensitivity.
3.3  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.
3.4  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 (8.2).
3.5  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 8).
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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 / 1000 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 / 1000 parts carbonate CD
1 part chlorite / 1000 parts chloride CD / UV / AD
1 part chlorite /  100 parts nitrite AD
* In case the quality requirements in clause 7 (e.g. see figures 2 and 3) are not achieved, the sample shall be
diluted.
4 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, 5.11).
Detection is by conductivity (CD), 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.
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).
5 Reagents
Use only reagents of recognized analytical grade. Carry out weighing with an accuracy of 1% of the nominal mass.
The water shall have an electrical conductivity of < 0,01 mS/m and shall not contain particulate matter of a particle
size > 0,45 μm. An increase in electrical conductivity due to an uptake of carbon dioxide does not interfere with the
determination.
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5.1  Sodium hydrogencarbonate, NaHCO
3
5.2  Sodium carbonate, Na CO
2 3
5.3  Tris(hydroxymethyl)aminomethane, NH C(CH OH)
2 2 3
5.4  Acetonitrile, CH CN
3
5.5  Sodium hydroxide solution, c(NaOH) = 0,1 mol/l
5.6  Benzoic acid, C H O
7 6 2
5.7  Potassium hydroxide solution, c(KOH), = 0,5 mol/l
5.8  Sodium chlorite, NaClO (80 %)
2
5.9  Sodium chloride, NaCl
5.10  Sodium chlorate, NaClO
3
5.11  Eluents
Different eluents are used, their choice depending on the type of separator column and detector. Therefore, follow
the column manufacturer´s instructions for the exact composition of the eluent. The eluent compositions described
in 5.11.1.2, 5.11.1.4, 5.11.2.2 and 5.11.2.3 are examples only.
A selection of reagents for common eluents is presented in 5.1 to 5.7. Preparing eluents from concentrates has
proved successful.
Degas all eluents. Take steps to avoid any renewed air pick-up during operation (e.g. by helium sparging). In order
to minimize the growth of bacteria or algae, store the eluents in the dark and renew every 3 d.
5.11.1  Examples of eluents for ion chromatography using the suppressor technique
For the application of the suppressor technique, sodium hydroxide and salt solutions of weakly dissociated acids
such as sodium carbonate/sodium hydrogencarbonate, sodium hydrogencarbonate, and sodium tetraborate can be
used.
5.11.1.1  Sodium carbonate/sodium hydrogencarbonate concentrate
For the eluent concentrate preparation:
Place 19,1 g of sodium carbonate (5.2) and 14,3 g of sodium hydrogencarbonate (5.1) into a graduated flask of
nominal capacity 1000 ml, dissolve in water (clause 5) and dilute to volume with water.
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.
5.11.1.2  Sodium carbonate/sodium hydrogencarbonate eluent
The following eluent is applicable for the determination of chlorate, chloride and chlorite:
Pipette 50 ml of the concentrate (5.11.1.1) into a graduated flask of nominal capacity 5000 ml and dilute to volume
with water (clause 5).
The solution contains 0,0018 mol/l of sodium carbonate and 0,0017 mol/l of sodium hydrogencarbonate. Store the
solution in amber-coloured glass and renew it every 3 d.
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5.11.1.3  Sodium hydrogencarbonate concentrate
For the eluent concentrate preparation:
Place 8,4 g of sodium hydrogencarbonate (5.1) into a graduated flask of nominal capacity 1000 ml, dissolve in water
(clause 5) and dilute to volume with water.
The solution contains 0,1 mol/l of sodium hydrogencarbonate. This solution is stable for several months if stored at
2 °C to 6 °C.
5.11.1.4  Sodium hydrogencarbonate eluent
The following eluent is applicable for the determination of chlorate, chloride and chlorite:
Pipette 50 ml of the concentrate (5.11.1.3) into a graduated flask of nominal capacity 5000 ml and dilute to volume
with water (clause 5).
The solution contains 0,001 mol/l of sodium hydrogencarbonate. Renew the solution every 3 d.
5.11.2  Examples of eluents for ion chromatography without using the suppressor technique
For ion chromatographic systems without suppressor devices, salt solutions, e.g. potassium hydrogenphthalate,
p-hydroxybenzoic acid, sodium borate/sodium gluconate, potassium hydroxide and sodium benzoate are used. The
solutions can contain various additions, e.g. alcohols. The concentration of the salts is usually in the range of
0,0005 mol/l to 0,01 mol/l.
5.11.2.1  Benzoic acid concentrate
For the eluent concentrate preparation:
Place 3,664 g of benzoic acid (5.6) into a beaker of capacity 1000 ml, add approximately 950 ml of water (clause 5).
Adjust the pH of the solution to approximately 4,2 with tris(hydroxymethyl)aminomethane (5.3; by adding it either as
a solid compound or as a concentrate solution). Stir and dissolve with gentle heating (60 °C to 80 °C). After
dissolving, transfer the cool solution into a graduated flask of nominal capacity 1000 ml and add 10 ml of acetonitrile
(5.4). Adjust the pH of the solution to 4,6 with tris(hydroxymethyl)aminomethane (5.3; by adding it either as a solid
compound or as a solution) and dilute to volume with water (clause 5).
The solution contains 0,03 mol/l of benzoic acid and approximately 1 % of acetonitrile and is stable for one month if
stored at 2 °C to 6 °C.
5.11.2.2  Benzoic acid eluent
For the determination of chlorate, chloride and chlorite, the following eluent has proved to be successful:
Place 100 ml of the concentrate (5.11.2.1) and 20 ml of acetonitrile (5.4) into a graduated flask of nominal capacity
1000 ml and dilute to volume with water (clause 5).
The solution contains 0,003 mol/l of benzoic acid and approximately 2 % of acetonitrile. The eluent pH is 4,65.
Renew the solution every 7 d.
5.11.2.3  Potassium hydroxide eluent
For the determination of chlorate, chloride and chlorite, the following eluent has proved to be successful:
Place 500 ml of water (clause 5) into a graduated flask of nominal capacity 1000 ml, add 10 ml of the potassium
hydroxide solution (5.7) and dilute to volume with water.
The solution contains 0,005 mol/l of potassium hydroxide. Renew the solution every 3 d.
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ISO 10304-4:1997(E)
5.12  Stock solutions
Prepare stock solutions of concentration ρ = 1000 mg/l for each of the anions chlorate, chloride and chlorite.
Dissolve the appropriate mass of each of the substances (5.8, 5.9, 5.10), prepared as stated in table 3, in
approximately 800 ml of water (clause 5, degassed with nitrogen or helium), in graduated flasks of nominal capacity
1000 ml, add 1 ml of sodium hydroxide solution (5.5). Dilute to volume with water. 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 Pretreatment Storage
derived from
subst.-portion
g/l
Chlorate NaClO 1,2753 ± 0,013 Dry in a desiccator In glass for 1 month if
3
only! kept at 2 °C to 6 °C
Chloride NaCl 1,6484 ± 0,017 Dry at 105 °C In polyethylene for 3
months if kept at 2 °C
to 6 °C
Chlorite* NaClO approx. 1,7 Dry in a desiccator In glass for 1 week if
2
only! 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).
5.13  Standard solutions
Depending upon the concentrations expected, prepare standard solutions of different anion composition and
concentration from the stock solutions (5.12). The risk of changes in concentration caused by interaction with the
vessel material increases with decreasing anion concentration. Store the standard solutions in polyethylene (PE)
vessels. Take into account that sodium chlorite salt can contain up to 20 % sodium chloride. Prepare chlorite
standard solutions as described in 5.13.2 to avoid chloride contamination, e.g. of the mixed standard solution
(5.13.1).
5.13.1  Mixed standard solution of chlorate and chloride
The mass concentrations of this solution are as follows:
– –
ρ(ClO , Cl ) = 10 mg/l
3
Pipette 1 ml of each of the chlorate and chloride stock solutions (5.12) into a graduated flask of nominal capacity
100 ml, add 0,1 ml of sodium hydroxide solution (5.5) and fill up to volume with water
...