Water quality - Preparation and treatment of poorly water-soluble organic compounds for the subsequent evaluation of their biodegradability in an aqueous medium (ISO 10634: 2018)

This document specifies techniques for preparing poorly water-soluble organic compounds (i.e. liquid
and solid compounds) with a solubility in water of less than approximately 100 mg/l and introducing
them into test vessels for a subsequent biodegradability test in an aqueous medium using standard
methods.
The subsequent tests on biodegradability are primarily methods using the analysis of the released
carbon dioxide described in ISO 9439 and the determination of the oxygen described in ISO 9408 and
following the usual precautions for ISO 10707. Thus, one can notice that the methods measuring the
removal of dissolved organic carbon (DOC) are not appropriate.
This document does not specify the biodegradation test methods. It is restricted to describing
techniques for introducing the test compounds into the test medium and to keeping them in a dispersed
state[4]. These techniques are implemented while observing the experimental conditions described
in the standardized methods for evaluating biodegradability. ISO 9439, based on CO2 evolution, is not
suitable for testing volatile compounds.
Some of the preparation methods described in this document might not be accepted by regulators for
making conclusions on the ready biodegradability of tested compounds.
Examples of biodegradability curves are given in Annex A.
2 Normative

Wasserbeschaffenheit - Anleitung für die Vorbereitung und Behandlung von in Wasser schwer löslichen organischen Verbindungen für die nachfolgende Bestimmung ihrer biologischen Abbaubarkeit in einem wässrigen Medium (ISO 10634:2018)

Dieses Dokument beschreibt Techniken zur Vorbereitung schwer wasserlöslicher Verbindungen (d. h. flüssige und feste Verbindungen) mit einer Wasserlöslichkeit von weniger als etwa 100 mg/l und zu ihrer Einbringung in Testgefäße zur nachfolgenden Prüfung auf biologische Abbaubarkeit in einem wässrigen Medium mittels genormter Verfahren.
Bei den nachfolgenden Tests auf biologische Abbaubarkeit handelt es sich in erster Linie um Verfahren zur Bestimmung des freigesetzten Kohlenstoffdioxids (siehe ISO 9439) und zur Bestimmung des Sauerstoffverbrauchs (siehe ISO 9408) unter Anwendung der üblichen Vorkehrungen nach ISO 10707. Verfahren, bei denen der Abbau von gelöstem organischem Kohlenstoff (DOC) (en: dissolved organic carbon) gemessen wird, eignen sich nicht.
In diesem Dokument werden keine Abbautestverfahren beschrieben. Es beschränkt sich auf die Beschreibung der Techniken zur Einbringung der Testsubstanzen in das Testmedium und zur Aufrechterhaltung des dispergierten Zustands [4]. Wenn diese Techniken angewendet werden, müssen die experimentellen Bedingungen, die in den genormten Abbauverfahren beschrieben sind, eingehalten werden. ISO 9439, bei dem die CO2 Entwicklung gemessen wird, ist für die Prüfung leichtflüchtiger Verbindungen nicht geeignet.
Einige der in diesem Dokument beschriebenen Vorbereitungsverfahren werden möglicherweise von Zulassungsbehörden für die abschließende Beurteilung der leichten biologischen Abbaubarkeit der geprüften Substanzen nicht akzeptiert.
Beispiele für Abbaukurven enthält Anhang A.

Qualité de l'eau - Préparation et traitement des composés organiques peu solubles dans l'eau en vue de l'évaluation de leur biodégradabilité en milieu aqueux (ISO 10634:2018)

Le présent document spécifie des méthodes de préparation de composés organiques peu solubles dans l'eau (c'est-à-dire, des composés liquides et solides) ayant une solubilité dans l'eau inférieure à environ 100 mg/l et leur introduction dans des récipients d'essai, en vue de réaliser un essai de biodégradabilité en milieu aqueux selon des méthodes normalisées.
Les essais de biodégradabilité applicables sont des méthodes utilisant l'analyse du dioxyde de carbone dégagé décrite dans l'ISO 9439 et la détermination de la demande en oxygène décrite dans l'ISO 9408 et respectant les précautions habituelles de l'ISO 10707. On peut ainsi noter que les méthodes de mesure de l'élimination du carbone organique dissous (COD) ne sont pas appropriées.
Le présent document ne décrit pas les méthodes d'essai de biodégradation. Il se limite à la description des méthodes d'introduction des composés d'essai dans le milieu d'essai et à leur maintien à l'état dispersé.[4] Ces méthodes sont mises en œuvre en respectant les conditions expérimentales décrites dans les méthodes normalisées pour l'évaluation de la biodégradabilité. L'ISO 9439, qui repose sur le dégagement de CO2, ne convient pas pour soumettre à essai les composés volatils.
Certaines des méthodes de préparation décrites dans le présent document peuvent ne pas être acceptées par les organismes de réglementation pour tirer des conclusions au sujet de la facilité de biodégradabilité des composés d'essai.
Des exemples de courbes de biodégradabilité sont donnés en Annexe A.

Kakovost vode - Priprava in obdelava v vodi slabo topnih organskih spojin za nadaljnje vrednotenje njihove biorazgradljivosti v vodi (ISO 10634:2018)

Ta dokument določa tehnike za pripravo v vodi slabo topnih organskih spojin (tj. spojin v tekočem in trdnem stanju), s topnostjo v vodi manj kot približno 100 mg/l, in njihovo vnašanje v preskusne posode za naknadni preskus biorazgradljivosti v vodnem mediju s standardnimi metodami.
Nadaljnji preskusi biorazgradljivosti so predvsem metode z uporabo analize sproščenega
ogljikovega dioksida, opisane v standardu ISO 9439, in določevanje kisika, opisano v standardu ISO 9408, ob upoštevanju običajnih varnostnih ukrepov v skladu s standardom ISO 10707. Tako lahko opazimo, da metode za merjenje odstranitve raztopljenega organskega ogljika (DOC) niso ustrezne.
Ta dokument ne določa metod za preskušanje biorazgradnje. Omejen je na opisovanje
tehnik za vnašanje preskusnih spojin v preskusni medij in njihovo vzdrževanje v razpršenem stanju [4]. Te tehnike se izvajajo ob upoštevanju preskusnih pogojev, opisanih v standardiziranih metodah za vrednotenje biorazgradljivosti. Standard ISO 9439, ki temelji na nastajanju CO2, ni primeren za preskušanje hlapnih spojin.
Nekaterih metod za pripravo, opisanih v tem dokumentu, regulatorji morda ne bodo sprejeli za sklepanje o lahki biorazgradljivosti preskušenih spojin.
Primeri krivulj biorazgradljivosti so podani v dodatku A.

General Information

Status
Published
Public Enquiry End Date
30-Sep-2017
Publication Date
10-Apr-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
04-Feb-2019
Due Date
11-Apr-2019
Completion Date
11-Apr-2019

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SLOVENSKI STANDARD
SIST EN ISO 10634:2019
01-maj-2019
1DGRPHãþD
SIST EN ISO 10634:1999
Kakovost vode - Priprava in obdelava v vodi slabo topnih organskih spojin za
nadaljnje vrednotenje njihove biorazgradljivosti v vodi (ISO 10634:2018)

Water quality - Preparation and treatment of poorly water-soluble organic compounds for

the subsequent evaluation of their biodegradability in an aqueous medium (ISO 10634:

2018)

Wasserbeschaffenheit - Anleitung für die Vorbereitung und Behandlung von in Wasser

schwer löslichen organischen Verbindungen für die nachfolgende Bestimmung ihrer
biologischen Abbaubarkeit in einem wässrigen Medium (ISO 10634:2018)

Qualité de l'eau - Préparation et traitement des composés organiques peu solubles dans

l'eau en vue de l'évaluation de leur biodégradabilité en milieu aqueux (ISO 10634:2018)

Ta slovenski standard je istoveten z: EN ISO 10634:2018
ICS:
13.060.70 Preiskava bioloških lastnosti Examination of biological
vode properties of water
SIST EN ISO 10634:2019 en,fr,de

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

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SIST EN ISO 10634:2019
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SIST EN ISO 10634:2019
EN ISO 10634
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2018
EUROPÄISCHE NORM
ICS 13.060.70 Supersedes EN ISO 10634:1995
English Version
Water quality - Preparation and treatment of poorly
water-soluble organic compounds for the subsequent
evaluation of their biodegradability in an aqueous medium
(ISO 10634: 2018)

Qualité de l'eau - Préparation et traitement des Wasserbeschaffenheit - Anleitung für die Vorbereitung

composés organiques peu solubles dans l'eau en vue de und Behandlung von in Wasser schwer löslichen

l'évaluation de leur biodégradabilité en milieu aqueux organischen Verbindungen für die nachfolgende

(ISO 10634:2018) Bestimmung ihrer biologischen Abbaubarkeit in einem
wässrigen Medium (ISO 10634:2018)
This European Standard was approved by CEN on 20 October 2018.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, 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

© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10634:2018 E

worldwide for CEN national Members.
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SIST EN ISO 10634:2019
EN ISO 10634:2018 (E)
Contents Page

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

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SIST EN ISO 10634:2019
EN ISO 10634:2018 (E)
European foreword

This document (EN ISO 10634:2018) 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 June 2019, and conflicting national standards shall be

withdrawn at the latest by June 2019.

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 10634:1995.

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, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
Endorsement notice

The text of ISO 10634:2018 has been approved by CEN as EN ISO 10634:2018 without any modification.

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SIST EN ISO 10634:2019
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SIST EN ISO 10634:2019
INTERNATIONAL ISO
STANDARD 10634
Second edition
2018-10
Water quality — Preparation and
treatment of poorly water-soluble
organic compounds for the subsequent
evaluation of their biodegradability in
an aqueous medium
Qualité de l'eau — Préparation et traitement des composés
organiques peu solubles dans l'eau en vue de l'évaluation de leur
biodégradabilité en milieu aqueux
Reference number
ISO 10634:2018(E)
ISO 2018
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SIST EN ISO 10634:2019
ISO 10634:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 10634:2019
ISO 10634:2018(E)
Contents Page

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

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

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

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

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

4 Presentation of suitable preparation and analytical methods............................................................................. 2

4.1 Preparation methods ......................................................................................................................................................................... 2

4.2 Analytical methods .............................................................................................................................................................................. 2

5 Direct addition and addition with inert support ................................................................................................................ 2

5.1 General ........................................................................................................................................................................................................... 2

5.2 Reagents........................................................................................................................................................................................................ 3

5.3 Apparatus .................................................................................................................................................................................................... 3

5.4 Procedure .................................................................................................................................................................................................... 3

5.4.1 Direct addition ................................................................................................................................................................... 3

5.4.2 Addition on inert support ........................................................................................................................................ 4

6 Ultrasonic and physical treatment..................................................................................................................................................... 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Apparatus .................................................................................................................................................................................................... 4

6.3 Procedure using an ultrasonic probe................................................................................................................................... 4

6.3.1 Preparation of the test compound .................................................................................................................... 4

6.3.2 Experimental protocol ................................................................................................................................................ 5

6.4 Procedure using an ultrasonic bath ...................................................................................................................................... 5

6.5 Other methods ......................................................................................................................................................................................... 5

7 Adsorption on an inert support with a volatile solvent removed from the system ........................6

7.1 General ........................................................................................................................................................................................................... 6

7.2 Reagents........................................................................................................................................................................................................ 6

7.3 Apparatus .................................................................................................................................................................................................... 6

7.4 Procedure .................................................................................................................................................................................................... 6

8 Addition with a non-biodegradable solvent or emulsifying agent ...................................................................7

8.1 General ........................................................................................................................................................................................................... 7

8.2 Reagents........................................................................................................................................................................................................ 7

8.3 Apparatus .................................................................................................................................................................................................... 8

9 Preliminary tests .................................................................................................................................................................................................. 9

9.1 Reagents........................................................................................................................................................................................................ 9

9.1.1 Selection of emulsifying agent concentration......................................................................................... 9

9.1.2 Selection of mineral oil concentration .......................................................................................................... 9

9.1.3 Selection of silicone oil concentration .......................................................................................................... 9

9.2 Procedure .................................................................................................................................................................................................... 9

9.2.1 Use of solvent ...................................................................................................................................................................... 9

9.2.2 Use of emulsifying agent ........................................................................................................................................10

9.2.3 Use of mineral oil ..........................................................................................................................................................10

9.2.4 Use of silicone oil ..........................................................................................................................................................10

9.3 Other additives .....................................................................................................................................................................................11

10 Combination of methods ...........................................................................................................................................................................11

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

Annex A (informative) Examples of biodegradability curves ..................................................................................................13

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

© ISO 2018 – All rights reserved iii
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SIST EN ISO 10634:2019
ISO 10634:2018(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 5,

Biological methods.

This second edition cancels and replaces the first edition (ISO 10634:1995), which has been technically

revised to take into account user feedback, new technologies and available reagents.

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 2018 – All rights reserved
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SIST EN ISO 10634:2019
ISO 10634:2018(E)
Introduction

The standardizing work carried out by ISO/TC 147/SC 5 has shown that the development of a single

method for evaluating the biodegradability of organic compounds with a low solubility in water

[1][2][3]

(i.e. < 100 mg/l ) cannot be envisaged in the immediate future. In fact, the selection of the most

suitable working method to obtain a satisfactory emulsion or dispersion of these compounds in the

test media depends particularly on their physicochemical properties. Consequently, the selection of the

most suitable method has to be left to the judgement of laboratories responsible for the tests based on

their experience and the product information supplied by the applicant. For this reason, this document

describes various techniques for treating poorly water-soluble organic compounds before they are

investigated for biodegradability tests. The objective is to reach a stage where, for any given technique,

the same working method is used by all laboratories, thus making it easier to compare results.

Specificities of the selected protocol should be kept in mind for the evaluation and interpretation of the

results of the biodegradation test.

The techniques described in this document will not necessarily produce the same biodegradability

results of the test compound if they are used in parallel. The use of solvents and dispersing or

emulsifying techniques can be additional sources of uncertainty and can lead to test results which

differ from those obtained without using these techniques. Furthermore, dispersions or emulsions can

be produced that would not exist as such in nature. It is recommended to perform biodegradability tests

with the direct addition of a test compound and using dispersion techniques in parallel because activity

of inoculum used should be comparable. The presence of microorganisms with potential to degrade the

test compound is assumed to be identical. The composition and activity might change when the tests

are conducted subsequently.

According to current standards for testing biodegradability, only pure or compounds containing a low

amount of impurities should be tested. Biodegradability tests are not recommended for heterogeneous

mixtures or multicomponent compounds as the results of such tests are difficult to interpret, especially

when the degradation is partial. Moreover, the use of solvents and dispersion techniques can lead

to unrepresentative heterogeneous distributions and to misleading test results in the subsequent

biodegradability tests.
© ISO 2018 – All rights reserved v
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SIST EN ISO 10634:2019
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SIST EN ISO 10634:2019
INTERNATIONAL STANDARD ISO 10634:2018(E)
Water quality — Preparation and treatment of poorly
water-soluble organic compounds for the subsequent
evaluation of their biodegradability in an aqueous medium

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 techniques for preparing poorly water-soluble organic compounds (i.e. liquid

and solid compounds) with a solubility in water of less than approximately 100 mg/l and introducing

them into test vessels for a subsequent biodegradability test in an aqueous medium using standard

methods.

The subsequent tests on biodegradability are primarily methods using the analysis of the released

carbon dioxide described in ISO 9439 and the determination of the oxygen described in ISO 9408 and

following the usual precautions for ISO 10707. Thus, one can notice that the methods measuring the

removal of dissolved organic carbon (DOC) are not appropriate.

This document does not specify the biodegradation test methods. It is restricted to describing

techniques for introducing the test compounds into the test medium and to keeping them in a dispersed

[4]

state . These techniques are implemented while observing the experimental conditions described

in the standardized methods for evaluating biodegradability. ISO 9439, based on CO evolution, is not

suitable for testing volatile compounds.

Some of the preparation methods described in this document might not be accepted by regulators for

making conclusions on the ready biodegradability of tested compounds.
Examples of biodegradability curves are given in Annex A.
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 9408, Water quality — Evaluation of ultimate aerobic biodegradability of organic compounds in

aqueous medium by determination of oxygen demand in a closed respirometer

ISO 9439, Water quality — Evaluation of ultimate aerobic biodegradability of organic compounds in

aqueous medium — Carbon dioxide evolution test

ISO 10707, Water quality — Evaluation in an aqueous medium of the “ultimate” aerobic biodegradability of

organic compounds — Method by analysis of biochemical oxygen demand (closed bottle test)

3 Terms and definitions
No terms and definitions are listed in this document.
© ISO 2018 – All rights reserved 1
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SIST EN ISO 10634:2019
ISO 10634:2018(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 Presentation of suitable preparation and analytical methods
4.1 Preparation methods

In this document, several techniques for introducing the test compounds into the test medium are

described. The preparation methods are as follows:

— direct addition: this technique is recommended for poorly soluble compounds instead of the

preparation of a stock solution;

— ultrasonic dispersion: this technique can be applied to non-volatile liquid and solid compounds;

— adsorption or weighing on an inert support;
— dispersion or solubilization with additive;
— combination of methods listed above.

NOTE Regarding the combination of methods, the techniques are generally run individually in parallel (i.e.

simultaneously by the same method and with the same inoculum) to gain insight into whether one technique is

dominant or whether both are contributing to enhance bioavailability and biodegradation.

4.2 Analytical methods

The test compound concentration shall fulfil the requirements of ISO 9439, ISO 9408 and ISO 10707.

When the test compound is introduced directly or on an inert support in the test vessel, it is not

necessary to confirm the tested concentration.

When the preparation method uses a stock solution of the tested compound, it is necessary to confirm

the concentration tested. For this purpose:

— a specific analytical method is required if the support or additive is an organic chemical (for example,

surfactant);

— the total organic carbon (TOC) analysis is acceptable if the support or additive is an inorganic

compound (for example, silica gel) or if a homogeneous dispersion is obtained by physical treatment

(for example, ultrasonic treatment).
5 Direct addition and addition with inert support
5.1 General

Biodegradability tests should be performed in parallel, with the direct addition of a test compound

and using dispersion techniques, because the activity of the inoculum used should be comparable. The

presence of microorganisms with the potential to degrade the test compound is assumed to be identical.

The test compound is weighed and directly introduced into the test vessels or weighed onto an inert

support and introduced into the test vessels, which are subjected to continuous agitation.

2 © ISO 2018 – All rights reserved
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SIST EN ISO 10634:2019
ISO 10634:2018(E)

Solid compounds can be grinded (e.g. using a mortar and a pestle) as finely as possible before weighing

them. Liquid nitrogen may be used.

NOTE Adding the tested substance adsorbed on inert support can affect the final biodegradation result. The

bioavailability of the compound can be limited by the adsorption to the inert support. Therefore, the measured

biodegradation result can decrease (e.g. if the adsorption to the surface of the inert material limits the access

of the tested substance to the inoculum). In the case of a tested compound that is toxic to microorganisms, the

limitation of the bioavailability could limit the toxic effect and increase the biodegradation result.

5.2 Reagents
5.2.1 Inert supports.

Silica gel, fibreglass filters, microscope slides or other non-biodegradable inert supports that do not

release organic or inorganic carbon into the aqueous medium can be used.

It should be validated by preliminary work that the support is inert and carbon-free. To avoid or

minimize surface area effects, the quantity of the support shall be minimal. The test compound should

be adsorbed on the surface.
For example, the following supports are suitable:
— microscopic slide;
— polyethylene slide;
— stainless steel slide;
— silica gel used for thin-layer chromatography (15 µm particle size);
— silica gel used for column chromatography (200 µm to 500 µm particle size).
5.3 Apparatus
5.3.1 Stirrers.

Sufficient stirrers are required to agitate all the test vessels used in a given biodegradability test except

for the closed bottle test (see ISO 10707).

Stirrer-rods shall be made of a material such that no ingredient of a plastic coat will contaminate the

test medium and no adsorption of test compounds will occur. Heating the test vessels by stirring and

raising the test temperature shall be avoided.
5.3.2 Vessels.

It is recommended to use laboratory glass or chemically inert labware for weighing and sample

preparations to avoid carbon contamination and adsorption of the test compound.
5.3.3 Mechanical disperser (e.g. Ultra-turrax ).
5.4 Procedure
5.4.1 Direct addition
Test compounds shall be weighed and directly added to the test vessels.

1) Ultra-turrax is an example of a suitable product available commercially. This information is given for the

convenience of users of this document and does not constitute an endorsement by ISO of this product.

© ISO 2018 – All rights reserved 3
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SIST EN ISO 10634:2019
ISO 10634:2018(E)

Non-viscous liquid compounds shall be added with a high precision volumetric syringe, taking into

account their relative density.
5.4.2 Addition on inert support
5.4.2.1 Solid test compound

Weigh onto the support (5.2.1) a quantity of the compound corresponding to the concentration of the

organic carbon required by the test method to be used.
Introduce a support into each of the test vessels.
Introduce a
...

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