ISO 23468:2021

Reactor technology — Power reactor analyses and measurements — Determination of heavy water isotopic purity by Fourier transform infrared spectroscopy

This document specifies an analytical method for determining heavy water isotopic purity by Fourier transform infrared spectroscopy (FTIR). It is applicable to the determination of the whole range of heavy water concentration. The method is devoted to process controls at the different steps of the process systems in heavy water reactor power plant or any other related areas. The method can be applied for heavy water isotopic purity measurements in a heavy water reactor power plant or research reactor, heavy water production factory and heavy water related areas.

Technologie du réacteur — Analyses et mesurages relatifs aux réacteurs de puissance — Détermination de la pureté isotopique de l’eau lourde par spectroscopie infrarouge à transformée de Fourier

General Information

• Status: Published
• Publication Date: 10-Aug-2021
• ICS: 27.120.10 - Reactor engineering
• Technical Committee: ISO/TC 85/SC 6 - Reactor technology
• Drafting Committee: ISO/TC 85/SC 6/WG 1 - Power reactor analyses and measurements
• Current Stage: 6060 - International Standard published
• Start Date: 11-Aug-2021
• Due Date: 11-Jul-2021
• Completion Date: 11-Aug-2021

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23468
First edition
2021-08
Reactor technology — Power reactor
analyses and measurements —
Determination of heavy water isotopic
purity by Fourier transform infrared
spectroscopy
Technologie du réacteur — Analyses et mesurages relatifs aux
réacteurs de puissance — Détermination de la pureté isotopique de
l’eau lourde par spectroscopie infrarouge à transformée de Fourier
Reference number
ISO 23468:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 23468:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 23468:2021(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents and materials . 3
6 Apparatus . 3
7 Heavy water reference standard preparation . 4
7.1 General requirements . 4
7.2 Storage of high isotopic purity heavy water reference standard. 4
7.2.1 Ampoule bottle . 4
7.2.2 Specially designed stainless steel container . 4
7.3 Lower D O concentration reference standard preparation . 4
2
8 Sampling . 5
8.1 General requirements . 5
8.2 Sampling with syringes . 5
8.3 Sampling with bottles . 5
9 Preparation of calibration curves of the method . 5
9.1 General . 5
9.2 Preparation of the apparatus . 6
9.2.1 FTIR spectrometer . 6
9.2.2 Infrared liquid cell . 7
9.3 Editing of the method . 7
9.4 Background spectrum . 7
9.5 Heavy water reference standard spectra . 7
9.6 Draw the calibration curves for different D O concentration ranges . 7
2
10 Procedure. 8
10.1 Sample preparation . 8
10.1.1 Sample temperature adjustment . 8
10.1.2 Sample filtration . 8
10.1.3 Sample source check . 8
10.2 Sample load and scan . 8
10.3 After measurement . 8
11 Expression of results . 9
11.1 Calculation method . 9
11.2 Precision . 9
11.3 Uncertainty .10
12 Interferences .10
12.1 Contaminated samples .10
12.2 Air bubbles .10
12.3 Foreign materials on the outside of the cell window .11
13 Test report .11
Annex A (informative) Specially designed stainless steel container for D O reference standard .12
2
Annex B (informative) Interested region suggested for typical curves .14
Bibliography .19
© ISO 2021 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 23468:2021(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 on 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 the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 6, Reactor technology.
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 2021 – All rights reserved

---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 23468:2021(E)
Reactor technology — Power reactor analyses and
measurements — Determination of heavy water isotopic
purity by Fourier transform infrared spectroscopy
1 Scope
This document specifies an analytical method for determining heavy water isotopic purity by Fourier
transform infrared spectroscopy (FTIR). It is applicable to the determination of the whole range of
heavy water concentration. The method is devoted to process controls at the different steps of the
process systems in heavy water reactor power plant or any other related areas.
The method can be applied for heavy water isotopic purity measurements in a heavy water reactor
power plant or research reactor, heavy water production factory and heavy water related areas.
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 3696, Water for analytical laboratory use — Specification and test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions are applied.
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 https:// www .electropedia .org/
3.1
heavy water
water which contains a higher than normal proportion of the heavy isotopes of hydrogen in combination
with oxygen
Note 1 to entry: HDO exists whenever there is water with hydrogen-1 and deuterium in the mix. HDO is formed
when hydrogen and deuterium atoms are rapidly exchanged between light water and heavy water molecules.
Note 2 to entry: Heavy water here does not mean “heavy water” which is enriched in the heavier oxygen isotopes
17 18
O and O.
Note 3 to entry: The ice point of heavy water is as high as 3,8 °C, care should be taken to avoid heavy water from
freezing.
[SOURCE: ISO 6107:2021, 3.272, modified — Notes 1 to 3 to entry were added.]
3.2
light water
water that contains natural abundance of protium and deuterium
© ISO 2021 – All rights reserved 1

---------------------- Page: 5 ----------------------
ISO 23468:2021(E)

3.3
Fourier transform infrared spectroscopy
FTIR
method in which a sample is subjected to excitation of molecular bonds by pulsed, broad-band infra-red
radiation and the Fourier transform mathematical method is used to obtain an absorption spectrum
[SOURCE: ISO/TS 80004-6:2021, 5.8]
3.4
D O
2
molecular formula of deuterium oxide
3.5
heavy water isotopic purity
c
atom
percentage of deuterium atoms in the total number of all hydrogen atoms including deuterium, protium
and tritium atoms
Note 1 to entry: Expressed as atom%.
3.6
D O concentration
2
c
mass
percentage of the mass of D O in total water mass, assuming that all of the deuterium exist in the form
2
of D O
2
Note 1 to entry: Expressed as mass fraction.
Note 2 to entry: The mass percentage of D O is deduced from heavy water isotopic purity which does not precisely
2
mean the mass percentage of D O in water because deuterium exists both in the form of HDO and D O.
2 2
3.7
precision
closeness of agreement between independent test results/measurement results obtained under
stipulated conditions
[SOURCE: ISO 3534-2:2006, 3.3.4]
4 Principle
HDO, D O and H O co-exist in heavy water, with Formula (1):
2 2
H O + D O ⇔ 2HDO (1)
2 2
The O-H bond and the O-D bond have each different infrared spectroscopy. Heavy water isotopic purity
is proportional to the absorption strength of characteristic region in infrared spectrum within certain
range of heavy water concentration.
Almost all protium in high isotopic purity heavy water, like a mass fraction from 98,500 to 100,000
in %, exists in the form of HDO, in which O-H has the biggest absorption at infrared wave number
−1
about 3 400 cm (λ is 2,94 μm). The absorption strength of this specified infrared wave number is
proportional to protium isotopic purity and proportional inversely to the deuterium isotopic purity in
heavy water. Almost all deuterium in low concentration of heavy water, like a mass fraction from 0,05 to
2,00 in %, exists in the form of HDO, in which O-D has the biggest absorption at infrared wave number
−1
about 2 500 cm (λ is 4,00 μm). The absorption strength of this specified infrared wave number is
proportional to deuterium isotopic purity and proportional to heavy water concentration.
For heavy water concentration in the range of a mass fraction from 2,00 to 98,50 in %, different ranges
could be subdivided according to different interested regions of the spectra respectively.
2 © ISO 2021 – All rights reserved

---------------------- Page: 6 ----------------------
ISO 23468:2021(E)

5 Reagents and materials
Use only reagents of recognized analytical grade, unless otherwise specified.
5.1 Demineralised light water, in accordance with the requirements of grade 1 as defined in ISO 3696.
5.2 High isotopic purity heavy water reference standards, a series of heavy water standards
with precisely characterized D O concentration, acquired from a certified laboratory and are free from
2
impurities and organic matters. Their conductivity should be less than 2 μS/cm.
5.3 Acetone or absolute ethyl alcohol.
5.4 Helium, with a purity of 99,999 % in volume.
5.5 Dry nitrogen or compressed air, with a dew point less than −30 °C.
6 Apparatus
The usual laboratory apparatus and, in particular, the following:
−1 −1 −1
6.1 FTIR spectrometer, with a resolution of 4 cm and a spectral range of 1 000 cm to 6 000 cm .
6.2 Infrared liquid cell, super-sealed liquid cells with Luer-Lock fittings for syringe filling of the
samples and shall have precise and reproducible path length. Two plugs are attached with each cell.
Different path lengths of cells like 0,5 mm, 0,3 mm, 0,2 mm, 0,1 mm, 0,05 mm may be prepared for the
method.
NOTE Liquid cells without temperature control are used in this standard method. A temperature controlled
liquid cell can be used for this method if necessary.
6.3 Hypodermic glass syringes, with Luer-Lock tips, clean and dry, always kept in a desiccator (6.9).
6.4 Disposable syringes.
6.5 Needles, with slip tips and suitable outer diameter.
6.6 Polyethylene or Polypropylene bottles, clean and dry, with tight caps.
6.7 Fume hood, with the inlet air flow in the range of (0,3 to 0,6) m/s.
6.8 Oven, with a temperature control model; the oven can heat up to 120 °C.
6.9 Desiccator.
6.10 Electrical analytical balance, which can be read to the nearest 0,1 mg.
6.11 Syringe filter, with the pore size of 0,45 µm.
6.12 Tissue paper, lint-free tissue paper for cleaning the cell window.
© ISO 2021 – All rights reserved 3

---------------------- Page: 7 ----------------------
ISO 23468:2021(E)

7 Heavy water reference standard preparation
7.1 General requirements
High isotopic purity heavy water reference standards (5.2) should be procured from a certified
laboratory. Heavy water reference standards of lower concentration may be prepared by mixing a high
isotopic purity heavy water standard and demineralized light water (5.1) in the laboratory according to
7.3.
7.2 Storage of high isotopic purity heavy water reference standard
7.2.1 Ampoule bottle
High isotopic purity heavy water degrades easily. The reference standards shall be enclosed in sealed
ampoule bottles and each shall be used only once.
7.2.2 Specially designed stainless steel container
Specially designed stainless steel container is recommended for the storage of high purity heavy water
reference standard, which is able to hold a relatively big amount of heavy water and prevent the heavy
water from degradation for a long time by covering the heavy water surface with pure helium (5.4). The
heavy water in the container can be extracted through a sampling port with rubber diaphragm. See
Annex A for reference.
If a container has not been sampled for several weeks, successive samples should be withdrawn and
analysed until two consecutive samples deviate within a mass fraction of 0,005 in %.
7.3 Lower D O concentration reference standard preparation
2
The relative humidity should be controlled under 40 %, preferably as low as possible, in the standard
preparation area of the laboratory. The bottles, pipettes or any other apparatus which will be used for
the standard preparation should be dry and of constant weight before the stand
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23468
ISO/TC 85/SC 6
Reactor technology — Power reactor
Secretariat: DIN
analyses and measurements —
Voting begins on:
2021­04­28 Determination of heavy water isotopic
purity by Fourier transform infrared
Voting terminates on:
2021­06­23
spectroscopy
Technologie du réacteur — Analyses et mesurages relatifs aux
réacteurs de puissance — Détermination de la pureté isotopique de
l’eau lourde par spectroscopie infrarouge à transformée de Fourier
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 SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 23468:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2021

---------------------- Page: 1 ----------------------
ISO/FDIS 23468:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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
CH­1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 23468:2021(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents and materials . 3
6 Apparatus . 3
7 Heavy water reference standard preparation . 4
7.1 General requirements . 4
7.2 Storage of high isotopic purity heavy water reference standard. 4
7.2.1 Ampoule bottle . 4
7.2.2 Specially designed stainless steel container . 4
7.3 Lower D O concentration reference standard preparation . 4
2
8 Sampling . 5
8.1 General requirements . 5
8.2 Sampling with syringes . 5
8.3 Sampling with bottles . 5
9 Preparation of calibration curves of the method . 5
9.1 General . 5
9.2 Preparation of the apparatus . 6
9.2.1 FTIR spectrometer . 6
9.2.2 Infrared liquid cell . 7
9.3 Editing of the method . 7
9.4 Background spectrum . 7
9.5 Heavy water reference standard spectra . 7
9.6 Draw the calibration curves for different D O concentration ranges . 7
2
10 Procedure. 7
10.1 Sample preparation . 7
10.1.1 Sample temperature adjustment . 7
10.1.2 Sample filtration . 8
10.1.3 Sample source check . 8
10.2 Sample load and scan . 8
10.3 After measurement . 8
11 Expression of results . 8
11.1 Calculation method . 8
11.2 Precision . 9
11.3 Uncertainty .10
12 Interferences .10
12.1 Contaminated samples .10
12.2 Air bubbles .10
12.3 Foreign materials on the outside of the cell window .10
13 Test report .11
Annex A (informative) Specially designed stainless steel container for D O reference standard .12
2
Annex B (informative) Interested region suggested for typical curves .14
Bibliography .19
© ISO 2021 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO/FDIS 23468:2021(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 non­governmental, 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 on 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 the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies,
and radiological protection, Subcommittee SC 6, Reactor technology.
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 2021 – All rights reserved

---------------------- Page: 4 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23468:2021(E)
Reactor technology — Power reactor analyses and
measurements — Determination of heavy water isotopic
purity by Fourier transform infrared spectroscopy
1 Scope
This document specifies an analytical method for determining heavy water isotopic purity by Fourier
transform infrared spectroscopy (FTIR). It is applicable to the determination of the whole range of
heavy water concentration. The method is devoted to process controls at the different steps of the
process systems in heavy water reactor power plant or any other related areas.
The method can be applied for heavy water isotopic purity measurements in a heavy water reactor
power plant or research reactor, heavy water production factory and heavy water related areas.
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 3696, Water for analytical laboratory use — Specification and test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions are applied.
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 https:// www .electropedia .org/
3.1
heavy water
water which contains a higher than normal proportion of the heavy isotopes of hydrogen in combination
with oxygen
Note 1 to entry: Hydrogen deuterium oxide (HDO) exists whenever there is water with hydrogen-1 and deuterium
in the mix. HDO is formed when hydrogen and deuterium atoms are rapidly exchanged between light water and
heavy water molecules.
Note 2 to entry: Heavy water here does not mean “heavy water” which is enriched in the heavier oxygen isotopes
17 18
O and O.
Note 3 to entry: The ice point of heavy water is 3,8 °C, care should be taken to avoid heavy water from freezing.
[SOURCE: ISO 6107­8:1993, 26]
3.2
light water
water that contains natural abundance of protium and deuterium
© ISO 2021 – All rights reserved 1

---------------------- Page: 5 ----------------------
ISO/FDIS 23468:2021(E)

3.3
Fourier transform infrared spectroscopy
FTIR
method in which a sample is subjected to excitation of molecular bonds by pulsed, broad-band infra-red
radiation and the Fourier transform mathematical method is used to obtain an absorption spectrum
[SOURCE: ISO/TS 80004­6:—, 5.8]
3.4
D O
2
molecular formula of deuterium oxide
3.5
heavy water isotopic purity
c
atom
percentage of deuterium atoms in the total number of all hydrogen atoms including deuterium, protium
and tritium atoms
Note 1 to entry: Expressed as atom%.
3.6
D O concentration
2
c
mass
percentage of the mass of D O in total water mass, assuming that all of the deuterium exist in the
2
form of D O
2
Note 1 to entry: Expressed as mass fraction.
Note 2 to entry: The mass percentage of D O is deduced from heavy water isotopic purity which does not precisely
2
mean the mass percentage of D O in water because deuterium exists both in the form of HDO and D O.
2 2
3.7
precision
closeness of agreement between independent test results/measurement results obtained under
stipulated conditions
[SOURCE: ISO 3534­2:2006, 3.3.4]
4 Principle
HDO, D O and H O co-exist in heavy water, with Formula (1):
2 2
H O + D O ⇔ 2HDO (1)
2 2
The O-H bond and the O-D bond have each different infrared spectroscopy. Heavy water isotopic purity
is proportional to the absorption strength of characteristic region in infrared spectrum within certain
range of heavy water concentration.
Almost all protium in high isotopic purity heavy water, like a mass fraction from 98,500 to 100,000
in %, exists in the form of HDO, in which O-H has the biggest absorption at infrared wave number
−1
about 3 400 cm (λ is 2,94 μm). The absorption strength of this specified infrared wave number is
proportional to protium isotopic purity and proportional inversely to the deuterium isotopic purity in
heavy water. Almost all deuterium in low concentration of heavy water, like a mass fraction from 0,05 to
2,00 in %, exists in the form of HDO, in which O-D has the biggest absorption at infrared wave number
−1
about 2 500 cm (λ is 4,00 μm). The absorption strength of this specified infrared wave number is
proportional to deuterium isotopic purity and proportional to heavy water concentration.
For heavy water concentration in the range of a mass fraction from 2,00 to 98,50 in %, different ranges
could be subdivided according to different interested regions of the spectra respectively.
2 © ISO 2021 – All rights reserved

---------------------- Page: 6 ----------------------
ISO/FDIS 23468:2021(E)

5 Reagents and materials
Use only reagents of recognized analytical grade, unless otherwise specified.
5.1 Demineralised light water, in accordance with the requirements of grade 1 as defined in ISO 3696.
5.2 High isotopic purity heavy water reference standards, a series of heavy water standards
with precisely characterized D O concentration, acquired from a certified laboratory and are free from
2
impurities and organic matters. Their conductivity should be less than 2 μS/cm.
5.3 Acetone or absolute ethyl alcohol.
5.4 Helium, with a purity of 99,999 % in volume.
5.5 Dry nitrogen or compressed air, with a dew point less than −30 °C.
6 Apparatus
The usual laboratory apparatus and, in particular, the following:
−1 −1 −1
6.1 FTIR spectrometer, with a resolution of 4 cm and a spectral range of 1 000 cm to 6 000 cm .
6.2 Infrared liquid cell, super-sealed liquid cells with Luer-Lock fittings for syringe filling of the samples
and shall have precise and reproducible path length. Two plugs are attached with each cell. Different path
lengths of cells like 0,5 mm, 0,3 mm, 0,2 mm, 0,1 mm, 0,05 mm may be prepared for the method.
NOTE Liquid cells without temperature control are used in this standard method. A temperature controlled
liquid cell can be used for this method if necessary.
6.3 Hypodermic glass syringes, with Luer-Lock tips, clean and dry, always kept in a desiccator (6.9).
6.4 Disposable syringes.
6.5 Needles, with slip tips and suitable outer diameter.
6.6 Polyethylene or Polypropylene bottles, clean and dry, with tight caps.
6.7 Fume hood, with the inlet air flow in the range of (0,3 to 0,6) m/s.
6.8 Oven, with a temperature control model; the oven can heat up to 120 °C.
6.9 Desiccator.
6.10 Electrical analytical balance, which can be read to the nearest 0,1 mg.
6.11 Syringe filter, with the pore size of 0,45 µm.
6.12 Tissue paper, lint­free tissue paper for cleaning the cell window.
© ISO 2021 – All rights reserved 3

---------------------- Page: 7 ----------------------
ISO/FDIS 23468:2021(E)

7 Heavy water reference standard preparation
7.1 General requirements
High isotopic purity heavy water reference standards (5.2) should be procured from a certified laboratory.
Heavy water reference standards of lower concentration may be prepared by mixing a high isotopic purity
heavy water standard and demineralized light water (5.1) in the laboratory according to 7.3.
7.2 Storage of high isotopic purity heavy water reference standard
7.2.1 Ampoule bottle
High isotopic purity heavy water degrades easily. The reference standards shall be enclosed in sealed
ampoule bottles and each shall be used only once.
7.2.2 Specially designed stainless steel container
Specially designed stainless steel container is recommended for the storage of high purity heavy water
reference standard, which is able to hold a relatively big amount of heavy water and prevent the heavy
water from degradation for a long time by covering the heavy water surface with pure helium (5.4). The
heavy water in the container can be extracted through a sampling port with rubber diaphragm. See
Annex A for reference.
If a container has not been sampled for several weeks, successive samples should be withdrawn and
analysed until two consecutive samples deviate within a mass fraction of 0,005 in %.
7.3 Lower D O concentration reference standard preparation
2
The relative humidity should be controlled under 40 % in the standard preparation area of the
laboratory. The bottles, pipettes or any other apparatus which will be used for the standard preparation
should be dry and of constant weight before the standard preparation.
Lower D O concentration of heavy water reference standards can be prepared in a clean and dry bottle
2
by mixing appropriate volume of a high purity heavy water reference standard with appropriate volume
of demineralized light wate
...