SIST EN ISO 5667-3:2024

SLOVENSKI STANDARD
01-maj-2024
Nadomešča:
SIST EN ISO 5667-3:2018
Kakovost vode - Vzorčenje - 3. del: Konzerviranje in ravnanje z vzorci vode (ISO
5667-3:2024)
Water quality - Sampling - Part 3: Preservation and handling of water samples (ISO 5667
-3:2024)
Wasserbeschaffenheit - Probenahme - Teil 3: Konservierung und Handhabung von
Wasserproben (ISO 5667-3:2024)
Qualité de l'eau - Échantillonnage - Partie 3: Conservation et manipulation des
échantillons d'eau (ISO 5667-3:2024)
Ta slovenski standard je istoveten z: EN ISO 5667-3:2024
ICS:
13.060.45 Preiskava vode na splošno Examination of water in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 5667-3
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2024
EUROPÄISCHE NORM
ICS 13.060.45 Supersedes EN ISO 5667-3:2018
English Version
Water quality - Sampling - Part 3: Preservation and
handling of water samples (ISO 5667-3:2024)
Qualité de l'eau - Échantillonnage - Partie 3: Wasserbeschaffenheit - Probenahme - Teil 3:
Conservation et manipulation des échantillons d'eau Konservierung und Handhabung von Wasserproben
(ISO 5667-3:2024) (ISO 5667-3:2024)
This European Standard was approved by CEN on 1 March 2024.

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

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

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 5667-3:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 5667-3:2024) 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 October 2024, and conflicting national standards shall
be withdrawn at the latest by October 2024.
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 5667-3:2018.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 5667-3:2024 has been approved by CEN as EN ISO 5667-3:2024 without any
modification.
International
Standard
ISO 5667-3
Sixth edition
Water quality — Sampling —
2024-03
Part 3:
Preservation and handling of
water samples
Qualité de l'eau — Échantillonnage —
Partie 3: Conservation et manipulation des échantillons d'eau
Reference number
ISO 5667-3:2024(en) © ISO 2024

ISO 5667-3:2024(en)
© ISO 2024
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
ii
ISO 5667-3:2024(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms for plastics . 2
5 Sampling and chain of custody . 3
6 Reagents and materials . 3
6.1 Solids .3
6.2 Solutions .4
6.3 Materials .5
7 Containers . 5
7.1 Container selection and preparation .5
7.2 On-site filtration . .6
7.3 Filling the container .6
8 Sample handling and preservation . 6
8.1 General .6
8.2 Sample handling and preservation for physical and chemical analysis .7
8.3 Sample handling and preservation for hydrobiological analysis .7
8.4 Sample handling and preservation for radiochemical analysis .8
9 Sample transport . 8
10 Identification of samples . 9
11 Sample reception . 9
12 Sample storage . 9
Annex A (informative) Techniques for sample preservation .11
Annex B (informative) Container preparation .58
Bibliography .59

iii
ISO 5667-3:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 6,
Sampling (general 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 sixth edition cancels and replaces the fifth edition (ISO 5667-3:2018), which has been technically
revised.
The main changes are as follows:
— ISO/TS 5667-25 has been added as a reference;
— a flow diagram for preservation and storage of water samples has been added;
— references in Table A.1 have been updated;
— references in Tables A.2 and A.3 have been added;
— the previous Table A.1 has been split into Table A.1 on inorganic analytes and Table A.2 on organic
analytes;
— Table A.4 on microbiological analysis has been added;
— types of water have been added to Tables A.1 to A.5;
— the added terms used in Tables A.1 to A.5 have been explained.
A list of all parts in the ISO 5667 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 5667-3:2024(en)
Introduction
This document is intended to be used in conjunction with ISO 5667-1, which deals with the design of sampling
programmes and sampling techniques.
Where possible, this document has been aligned with current standards. Where new research or validation
results have provided new insights, the latest knowledge has been used.
[87]
Guidance on validation protocols can be found in ISO/TS 5667-25 and ISO 17034 .
Tables A.1 to A.5 provide the validated preservation times or conditions as well as the descriptions of best
practice. Tables A.1 to A.5 also refer, for each analyte, to references available at the time of publication of this
document (i.e. ISO 5667-3:2024). This is however not an exhaustive list. Other preservation methods may be
used when they have been validated. However, it is strongly recommended that, where a method validation
is not available, the preservation times for the analyte listed in Tables A.1 to A.5 for ISO test methods be
followed. In case more than one storage time is provided in Tables A.1 to A.5, the order of preferred use is:
— validated method;
— method provided by reference;
— best practice.
The preservation and storage conditions and maximum storage times per analyte as listed in Tables A.1 to
A.5 should be regarded as default conditions to be applied in the absence of any other information.
However, if validation of preservation techniques and holding times has been carried out, relative to specific
circumstances and matrices, by a laboratory, then, provided that it can produce evidence of this validation
where they differ from those set out in Tables A.1 to A.5, these validated preservation and storage conditions
and maximum storage times are deemed acceptable for use by the validating laboratories. A national
standard can contain information on preservation.
This document and the related analytical references can be used as presented in Figure 1.

v
ISO 5667-3:2024(en)
WARNING — ‘Method provided by reference’ and ‘validated method’ can be based on previous standards
and methods and therefore not be in line with ISO/TS 5667-25. This information can be interpreted by
a qualified and experienced person.
Figure 1 — Flow diagram for the selection of a method for the preservation and storage of water samples
Attention is drawn to ISO/TS 5667-25, which contains guidelines and the elaboration of the required
techniques of how to validate new storage times or preservative methods and details of the techniques
described.
vi
International Standard ISO 5667-3:2024(en)
Water quality — Sampling —
Part 3:
Preservation and handling of water samples
1 Scope
This document specifies the general requirements for sampling, preservation, handling, transport
and storage of all water samples for physicochemical, chemical, hydrobiological and microbiological analyses
and determination of radiochemical analytes and activities.
Guidance on the validation of storage times of water samples is provided in ISO/TS 5667-25.
This document is not applicable to water samples intended for ecotoxicological assays, biological assays
(which is specified in ISO 5667-16), passive sampling (which is specified in ISO 5667-23) and microplastics
(which is specified in ISO 5667-27).
This document is particularly appropriate when samples cannot be analysed on site and have to be
transported to a laboratory for analysis.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 19458:2006, Water quality — Sampling for microbiological analysis
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
best practice
method based upon consensus or general use and that can be referred to in literature
Note 1 to entry: Given the differences in conditions and circumstances as well as the impossibility to validate
all parameters from a validated method (3.7) or technique or process, a best practice method based upon the
corresponding properties of a validated parameter can be used.
3.2
integrity
property of the parameter(s) of interest, information or content of a sample stored in a container that has
not been altered or lost in an unauthorized manner or that has been subject to loss of representativeness

ISO 5667-3:2024(en)
3.3
method provided by reference
procedure or technique for the preservation of samples taken from the reference to which it refers
Note 1 to entry: It is not in all cases clear whether the preservation procedure provided by the reference was validated
method (3.7), a best practice (3.1) or which procedure was used for its determination or validation. Where available,
the information about the matrices is taken over.
3.4
sample preservation
procedure used to stabilize a sample in such a way that the properties under examination are maintained
stable from the collection step until preparation for analysis
Note 1 to entry: Different analytes can require several samples from the same source that are stabilized by different
procedures.
[SOURCE: ISO 11074:2015, 4.4.20, modified — Note 1 to entry has been added.]
3.5
sample storage
process and result of keeping a sample available under predefined conditions, usually for a specified time
interval between collection and further treatment of a sample
Note 1 to entry: The specified time is the maximum time interval.
[SOURCE: ISO 11074:2015, 4.4.22, modified — Note 1 to entry has been added; “soil sample” has been
changed to “sample”.]
3.6
storage time
period of time between filling of the sample container and further treatment of the sample in the laboratory,
if stored under predefined conditions
Note 1 to entry: Sampling finishes as soon as the sample container has been filled with the sample. Storage time ends
when the sample is taken by the analyst to start sample preparation prior to analysis.
Note 2 to entry: Further treatment is, for most analytes, a solvent extraction or acid destruction. The initial steps
of sample preparation can be steps complementary to the storage conditions for the maintenance of analyte
concentrations.
3.7
validated method
method for which the validity or correctness has been checked by verification or qualification against a
number of predefined requirements
Note 1 to entry: A validated method indicates that a preservation method is capable of delivering the intended results
with an acceptable degree of uncertainty for the parameter or group of parameters and water type.
4 Abbreviated terms for plastics
FEP perfluoro(ethylene/propylene)
PE polyethylene
PE-HD high density polyethylene
PET polyethylene terephthalate
PFA perfluoroalkoxy (polymer)
PP polypropylene
ISO 5667-3:2024(en)
PTFE polytetrafluoroethylene
PVC poly(vinyl chloride)
5 Sampling and chain of custody
If there is a need to take samples, this is done according to a sampling programme. The first step is to design
a sampling programme. Guidance on this topic is given in ISO 5667-1.
Depending on the sample type and matrix, the instruction found in the relevant part(s) of the ISO 5667 series
and in ISO 19458 should be consulted.
The process of preservation and handling of water samples consists of several steps. During this process,
the responsibility for the samples can change. To ensure the integrity of the samples, all steps involving the
sample shall be documented.
6 Reagents and materials
WARNING — Certain preservatives (e.g. acids, alkalis, formaldehyde) need to be used with caution.
Sampling personnel should be warned of potential dangers and appropriate safety procedures
should be followed.
The following reagents are used for the sample preservation and shall only be prepared in accordance
with individual sampling requirements. All reagents and waters used shall be of at least analytical grade.
Acids referred to in this document are commercially available “concentrated” acids.
All reagents shall be labelled with a “shelf-life” representing the period for which the reagent is suitable for
use, if stored correctly. Any reagents that are unused beyond the shelf-life shall be discarded.
NOTE The shelf-life of reagents is often supplied by the receiving laboratory.
Check reagents periodically, for example, by field blanks, and discard any reagent found to be unsuitable.
For reagents that are unlikely to change over time in the specific conditions, check periodically if storage
and packaging still meet the requirements.
Between on-site visits, reagents shall be stored separately from sample containers and other equipment in a
clean, secure cabinet in order to prevent contamination.
Each sample shall be labelled accordingly, after the addition of the preservative. Otherwise, there is no
visible indication as to which samples have been preserved and which have not.
6.1 Solids
6.1.1 Sodium thiosulfate pentahydrate, Na S O ·5H O, w(Na S O ·5H O) > 99 %.
2 2 3 2 2 2 3 2
6.1.2 Sodium hydroxide, NaOH, w(NaOH) > 99 %.
6.1.3 Sodium tetraborate decahydrate, Na B O ·10H O, w(Na B O ·10H O) > 99 %.
2 4 7 2 2 4 7 2
CAUTION — Sodium tetraborate decahydrate is known to be a reproductive toxin.
6.1.4 Hexamethylenetetramine (hexamine, urotropine), C H N , w(C H N ) > 99 %.
6 12 4 6 12 4
6.1.5 Potassium iodide, KI, w(KI) > 99 %.
6.1.6 Iodine, I w(I ) > 99 %.
2, 2
ISO 5667-3:2024(en)
6.1.7 Sodium acetate, C H NaO , w(C H NaO ) > 99 %.
2 3 2 2 3 2
6.1.8 Ethylenediamine, C H N , w(C H N ) > 99 %.
2 8 2 2 8 2
6.2 Solutions
6.2.1 Zinc acetate solution C H O Zn⋅2H O (100 g/l).
4 6 4 2
Dissolve 10,0 g of zinc acetate dihydrate in approximately 90 ml of water. Dilute to 100 ml with water.
6.2.2 Orthophosphoric acid (ρ ≈ 1,7 g/ml), H PO , w(H PO ) > 85 %, c(H PO ) = 15 mol/l.
3 4 3 4 3 4
6.2.3 Hydrochloric acid (ρ ≈ 1,2 g/ml), HCl, w(HCl) > 36 %, c(HCl) = 12,0 mol/l.
6.2.4 Nitric acid (ρ ≈ 1,42 g/ml), HNO , w(HNO ) > 65 %, c(HNO ) = 15,8 mol/l.
3 3 3
6.2.5 Sulfuric acid (ρ ≈ 1,43 g/ml), H SO , w(H SO ) ≈ 49 %, c(H SO ) ≈ 9 mol/l.
2 4 2 4 2 4
Dilute concentrated sulfuric acid (H SO ), ρ ≈ 1,84 g/ml, w(H SO ) ≈ 98 % 1 + 1 by carefully adding
2 4 2 4
the concentrated acid to an equal volume of water and mix.
WARNING — Adding the concentrated acid to the water can give violent reactions because of an
exothermic reaction.
6.2.6 Sodium hydroxide solution (0,40 g/ml), NaOH.
6.2.7 Formaldehyde solution (formalin), CH O, φ(CH O) = 37 % (freshly prepared).
2 2
WARNING — Beware of formaldehyde vapours. Do not store large numbers of samples in small
working areas.
6.2.8 Disodium salt of ethylenediaminetetraacetic acid (EDTA) (0,025 g/ml), C H N Na O ⋅2H O,
10 14 2 2 8 2
w(C H N Na O ⋅2H O) > 99 %.
10 14 2 2 8 2
Dissolve 25 g EDTA in 1 000 ml of water.
6.2.9 Ethanol, C H OH, φ(C H OH) = 96 %.
2 5 2 5
6.2.10 Acidic Lugol’s solution, 100 g potassium iodide (6.1.5), 50 g iodine (6.1.6) and 100 ml glacial acetic
acid (6.2.16) in 1 000 ml water to pH 2.
6.2.11 Alkaline Lugol’s solution, 100 g potassium iodide (6.1.5), 50 g iodine (6.1.6) and 250 g sodium
acetate (6.1.7) in 1 000 ml water to pH 10.
6.2.12 Neutralized formaldehyde solution, formaldehyde solution (6.2.7) neutralized with sodium
tetraborate (6.1.3) or hexamethylenetetramine (6.1.4). Formalin solution at 100 g/l gives a final solution of
φ(CH O) = 3,7 %.
WARNING — Beware of formaldehyde vapours. Do not store large numbers of samples in small
working areas.
6.2.13 Ethanol preservative solution.
Ethanol (6.2.9), formaldehyde solution (6.2.7) and glycerol (6.2.17) (100 + 2 + 1 parts by volume, respectively).

ISO 5667-3:2024(en)
6.2.14 Sodium hypochlorite, NaOCl, w(NaOCl) = 10 %.
Dissolve 100 g sodium hypochlorite (NaOCl) in 1 000 ml of water.
6.2.15 Potassium iodate, KIO , w(KIO ) = 10 %.
3 3
Dissolve 100 g potassium iodate (KIO ) in 1 000 ml of water.
6.2.16 Glacial acetic acid, C H O , w(C H O ) > 99 %.
2 4 2 2 4 2
6.2.17 Glycerol (glycerin, glycerine), C H (OH) .
3 5 3
6.2.18 Sodium hydrogen sulfate, NaHSO .
6.2.19 Sodium thiosulfate pentahydrate solution, ρ(Na S O ⋅5H O) = 18 mg/ml.
2 2 3 2
6.3 Materials
6.3.1 Container and cap.
The types of containers and caps are specified in Tables A.1 to A.5.
6.3.2 Membrane filter, with pore size 0,40 µm to 0,45 µm.
7 Containers
7.1 Container selection and preparation
The choice of sample container (6.3.1) is of major importance and ISO 5667-1 provides some guidance on this
subject.
Details of the type of container used for the collection and storage of samples are given in Tables A.1 to A.5.
The same considerations given to this selection of suitable container material shall also be given to the
selection of cap liner materials.
For microbiological analyses, clean sterile bottles shall be used. If the water contains an oxidant, stop the
action of the oxidant as soon as the sample is taken by adding a reducing agent. Add a reducing agent such
as sodium thiosulfate to the sample bottles. The theoretical mass of sodium thiosulfate (pentahydrate)
necessary to inactivate 1 mg of chlorine is 7,1 mg. Thus, 0,1 ml of sodium thiosulfate pentahydrate solution
(6.2.19) is added for each 100 ml of bottle capacity. This will inactivate at least 2 mg/l and up to 5 mg/l of
free chlorine residual, depending on inactivation dynamics, which is sufficient for the majority of samples.
In certain circumstances, such as foot baths in swimming pools, disinfection measures (e.g. Legionella
eradication in drinking water distribution systems), higher chlorine concentrations can be found and a
proportionately higher dosage of sodium thiosulfate will be necessary. Sodium thiosulfate is not destroyed
by autoclaving or dry heat.
For other disinfectants, corresponding inactivation measures need to be taken. If inactivation is not possible
or feasible, it has to be reported. Chelating agents have been recommended to protect bacteria from the
toxic action of heavy metals such as copper or zinc. Ethylene dinitrilotetraacetic acid (EDTA) or sodium
nitrilotriacetate (NTA) (Na C H NO ) can be used as a filter-sterilized solution at a final concentration of
3 6 6 6
about 50 mg/l but should only be added when necessary (e.g. water treated with silver or copper). More
information is specified in ISO 19458.
Containers used for microbiological samples shall be tested to ensure sterility. Either by a certificate from
the supplier or in-house control. If disinfection agents have been added, the concentration shall also be
monitored. Guidance on this subject is provided in ISO 19458.

ISO 5667-3:2024(en)
Sample containers shall be made of a material appropriate for preserving the natural properties of both
the sample and the expected range of contaminants. Suitable types of containers for each analyte to be
measured are given in Tables A.1 to A.5.
NOTE For very low concentrations of metals, containers prescribed can be different from those used for higher
concentrations. Details can be found in Table A.1 or in the analytical International Standards.
If the samples are to be frozen, suitable containers, such as polyethylene (PE) or polytetrafluoroethylene
(PTFE), shall be used to prevent breakage.
The use of disposables is preferred due to lower risks of contamination. Some manufacturers supply
containers with a certificate of cleanliness. If such a certificate of cleanliness is supplied, it is not necessary
to clean or rinse the containers before use.
More information on container preparation can be found in Annex B.
7.2 On-site filtration
On-site filtration using a membrane filter (6.3.2) is required in some cases such as:
— if the dissolved metals need to be analysed, then acidify to pH < 2 after filtration;
— if required according to Tables A.1 to A.5, e.g. ammonium, nitrate, nitrite, phosphate, sulfate and silicates.
If experience has shown that no significant amount of particles occur (e.g. in drinking water), the filtration
may be omitted. Those samples shall be colourless and shall have a turbidity <1,5 FNU (formazine
nephelometric unit).
If immediate filtration on site is impossible when required (for instance under freezing weather conditions),
then the reason and the time between sampling and filtration shall be added to the test report.
7.3 Filling the container
Containers (6.3.1) should be filled as prescribed in Tables A.1 to A.5 or in the analytical International
Standard. If there are no instructions regarding the filling of the containers, they should be filled completely,
unless the samples are to be frozen as part of their preservation. In this case, the sample containers shall not
be filled completely in order to prevent breakage which can arise from the expansion of the water sample
during the freezing and thawing process.
For microbiological samples, the filling procedure described in ISO 19458 shall be followed.
If no preservatives are present in the bottle, prerinsing the bottle is advisable. Guidance on prerinsing can
be found in ISO 5667-14.
8 Sample handling and preservation
8.1 General
Waters, particularly surface waters, waste waters and groundwaters, are susceptible to changes as a result
of physical, chemical or hydrobiological reactions which can take place between the time of sampling
and the commencement of analysis. The nature and rate of these reactions are often such that, if precautions
are not taken during sampling, transport and storage (for specific analytes), the concentrations determined
are different to those existing at the time of sampling.
The extent of these changes is dependent on the chemical and biological nature of the sample, its temperature,
its exposure to light, the type of container in which it is placed, the time between sampling and analysis, and
the conditions to which it is subjected, e.g. agitation during transport.

ISO 5667-3:2024(en)
8.2 Sample handling and preservation for physical and chemical analysis
Changes to particular constituents vary both in degree and rate, not only as a function of the type of water,
but also, for the same water type, as a function of seasonal conditions.
These changes are often sufficiently rapid to modify the sample considerably in a short time. In all cases, it
is essential to take precautions to minimize these reactions and, in the case of many analytes, to analyse the
sample with a minimum of delay.
Further specific causes of variation are listed in a) to f).
a) The presence of bacteria, algae and other organisms can consume certain constituents of the samples.
These organisms can also modify the nature of the constituents to produce new constituents.
This hydrobiological activity affects, for example, the concentrations of dissolved oxygen, carbon
dioxide, compounds of nitrogen, phosphorus and, sometimes, silicon.
b) Certain compounds can be oxidized either by dissolved oxygen present in the samples, or by atmospheric
oxygen [e.g. organic compounds, Fe(II) and sulfides].
c) Certain substances can precipitate out of solution [e.g. calcium carbonate, metals and metallic
compounds such as Al(OH) ] or can be lost to the vapour phase (e.g. oxygen, cyanides and mercury).
d) Absorption of carbon dioxide from the air can modify the pH, conductivity and the concentration
of dissolved carbon dioxide. The passage of compounds like ammonia and silicon fluoride through some
types of plastics (see Table A.1) can also affect pH or conductivity.
e) Dissolved metals or metals in a colloidal state, as well as certain organic compounds, can be irreversibly
adsorbed on to the surface of the containers or solid materials in the samples.
f) Polymerized products can depolymerize and, conversely, simple compounds can polymerize.
On-site filtration can be required as a precaution (7.2).
Samples for element analysis that are preserved with acid, can be transported under room temperature.
Details of the sample preservation are given in Tables A.1 and A.2.
8.3 Sample handling and preservation for hydrobiological analysis
The handling of samples for hydrobiological analysis is different from that for samples requiring chemical
analysis. The addition of chemicals to the sample for hydrobiological analysis can be used for fixation
or preservation of the sample. The term “fixation” is defined as the protection of morphological structures,
while the term “preservation” is defined as the protection of organic matter from biochemical or chemical
degradation. Preservatives, by definition, are toxic, and the addition of preservatives can lead to the death of
living organisms. Prior to death, irritation can cause the most delicate organisms, which do not have strong
cell walls, to collapse before fixation is complete. To minimize this effect, it is important that the fixation
agent enters the cell quickly.
IMPORTANT — Acidic Lugol's solutions (6.2.10) can lead to the loss of structures in organisms or to
the loss of small organisms, e.g. some flagellates. An alkaline Lugol's solution (6.2.11) should be used
when silico-flagellates are frequently observed, e.g. during the summer.
The fixing and/or preservation of samples for hydrobiological analysis shall meet the following criteria:
a) the effect of the fixative and/or preservative on the loss of the organism shall be known beforehand;
b) the fixative or preservative shall effectively prevent the biological degradation of organic matter at least
during the storage period of the samples;
c) the fixative, and/or preservative, shall enable the hydrobiological analyte (e.g. organisms or taxonomical
groups) to be assessed during the storage period of the samples.
Details of the sample preservation are given in Table A.3.

ISO 5667-3:2024(en)
8.4 Sample handling and preservation for radiochemical analysis
WARNING — Radioprotection, such as shielding, can be necessary, depending on the activity
of the sample.
There is little difference between the handling of samples for radiochemical analysis and the handling
of samples for physicochemical analysis.
The delay between sampling and measurement has to be consistent with the radioactive half-life of the
radionuclides of interest. The conditions for adequate storage are independent of the radioactive half-life,
but identical to those required for the corresponding stable isotope.
Cooling radiological samples is primarily used to prevent algal growth and biological spoilage. It is not
a necessary preservation step for radiochemical analyses.
Details of the sample preservation are given in Table A.5.
9 Sample transport
Cooling or freezing procedures shall be applied to samples to increase the time period available for transport
and storage (and if required, by Tables A.1 to A.5). When transport takes place, the sampling plan (e.g.
ISO 5667-1) shall consider:
— the time between sampling (end of filling the sample container intended for the laboratory) and start of
transport;
— the transport time;
— the time before further treatment in the laboratory.
The sum of these three periods is limited to the maximum storage times according to Tables A.1 to A.5.
If the maximum storage time cannot be met, then the sampling plan shall be reformulated to allow
these requirements to be accommodated. In case the requirements cannot be met, instructions are given
in ISO/TS 5667-25 to validate the preservation time of specific water samples or sample types.
Containers holding samples shall be protected and sealed during transport in such a way that the samples
do not deteriorate or lose any part of their content. Container packaging shall protect the containers
from possible external contamination, particularly near the opening, and should not itself be a source
of contamination.
Glass containers shall be protected from potential breakage during transport by appropriate packaging.
Samples shall be transported as soon as possible after sampling and with cooling (if necessary, according to
Tables A.1 to A.5).
Laboratory samples for dispatch or transport by third parties and preserved laboratory samples should be
sealed in such manner that the integrity of the sample can be maintained.
During transportation to the laboratory, samples shall be stored in a cooling device capable of maintaining
a temperature of 5 °C ± 3 °C, apart from samples for element analysis that are preserved with acid. The
samples intended for radiochemical analysis can be placed under room temperature. For proper evaluation
of the conditions during transport, a device capable of recording the (maximum) temperature of the air
surrounding the sample can be used. The temperature sensor should then be placed in a small container (e.g.
50 ml to 100 ml) filled with a fluid in order to avoid short time fluctuations in temperature.
Cooling and freezing procedures applied shall be in line with instructions from the analytical laboratory.
Freezing especially requires detailed control of the freezing and thawing process in order to return the
sample to its initial equilibrium after thawing.
Samples should not be in direct contact with the ice packs.
NOTE 1 Devices capable of logging the temperature during the transportation are available.

ISO 5667-3:2024(en)
NOTE 2 For the transport of samples from the field to the laboratory, the preferred fluid for measuring
the temperature is glycerol. If samples are transported in the field (e.g. on large locations), the fluid can also be, for
example, water.
10 Identification of samples
Container labels should withstand wetting, drying and freezing without detaching or becoming illegible.
The labelling system shall be waterproof to allow use on site.
The exact information given in the sampling report and on the sample labels depends on the objectives of the
particular measurement programme. In all cases, an indelible label shall be secured to the sample container.
For each sample, at least the following information shall be available.
— A unique identifier shall be available, traceable to:
— date, time and location of sampling;
— unique sample identification;
— description of sample;
— name of sampling personnel;
— details of sample preservation or fixation used;
— details of sample storage used;
— any information regarding integrity and manipulation of the sample;
— any other information, as necessary.
— A unique identifier, traceable to sample date, location and sample number shall appear on the label of the
sample container.
All other information is supplementary and should be detailed in the sampling report.
11 Sample reception
All relevant information regarding the sample in accordance with Clause 9 shall be recorded.
The laboratory shall receive and check information on sample preservation and sample transport conditions.
If at least one of the conditions is not met, a disclaimer shall be reported along with the results of the sample.
In all cases, and especially when a “chain of custody” process needs to be established, the number of sample
containers received in the laboratory shall be verified against the number of sample containers submitted.
12 Sample storage
The storage duration of the water samples is specific to the analyte(s) to be analysed. Samples should be
stored no longer than the maximum storage period given in Tables A.1 to A.5. The maximum storage time
includes the time between sampling (end of filling the sample container) and start of transport, the time of
transport and the starting time of analysis in the laboratory.
The refrigeration conditions within the laboratory shall be 3 °C ± 2 °C. Samples for microbiological
analysis shall be stored at 5 °C ± 3 °C. Samples for element analysis that are preserved with acid and those
intended for radiochemical analysis can be placed under room temperature. The te
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