SIST EN ISO 10993-12:2021

SLOVENSKI STANDARD
01-september-2021
Nadomešča:
SIST EN ISO 10993-12:2012
Biološko ovrednotenje medicinskih pripomočkov - 12. del: Priprava vzorcev in
referenčni materiali (ISO 10993-12:2021)
Biological evaluation of medical devices - Part 12: Sample preparation and reference
materials (ISO 10993-12:2021)
Biologische Beurteilung von Medizinprodukten - Teil 12: Probenvorbereitung und
Referenzmaterialien (ISO 10993-12:2021)
Évaluation biologique des dispositifs médicaux - Partie 12: Préparation des échantillons
et matériaux de référence (ISO 10993-12:2021)
Ta slovenski standard je istoveten z: EN ISO 10993-12:2021
ICS:
11.100.20 Biološko ovrednotenje Biological evaluation of
medicinskih pripomočkov medical devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10993-12
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2021
EUROPÄISCHE NORM
ICS 11.100.20 Supersedes EN ISO 10993-12:2012
English Version
Biological evaluation of medical devices - Part 12: Sample
preparation and reference materials (ISO 10993-12:2021)
Évaluation biologique des dispositifs médicaux - Partie Biologische Beurteilung von Medizinprodukten - Teil
12: Préparation des échantillons et matériaux de 12: Probenvorbereitung und Referenzmaterialien (ISO
référence (ISO 10993-12:2021) 10993-12:2021)
This European Standard was approved by CEN on 15 September 2020.

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

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

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10993-12:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Annex ZA (informative) Relationship between this European standard and the General
Safety and Performance Requirements of Regulation (EU) 2017/745 aimed to be
covered. 5

European foreword
This document (EN ISO 10993-12:2021) has been prepared by Technical Committee ISO/TC 194
"Biological and clinical evaluation of medical devices" in collaboration with Technical Committee
CEN/TC 206 “Biological and clinical evaluation of medical devices” 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 December 2021, and conflicting national standards
shall be withdrawn at the latest by December 2021.
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 10993-12:2012.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive(s).
For the relationship with EU Directive(s) see informative Annex ZA, which is integral part of this
document.
The following referenced documents are indispensable for the application of this document. For
undated references, the latest edition of the referenced document (including any amendments) applies.
For dated references, only the edition cited applies. However, for any use of this standard ‘within the
meaning of Annex ZA, the user should always check that any referenced document has not been
superseded and that its relevant contents can still be considered the generally acknowledged state-of-
art.
When an IEC or ISO standard is referred to in the ISO standard text, this shall be understood as a
normative reference to the corresponding EN standard, if available, and otherwise to the dated version
of the ISO or IEC standard, as listed below.
NOTE The way in which these referenced documents are cited in normative requirements determines the
extent (in whole or in part) to which they apply.
Table — Correlations between undated normative references and dated EN and ISO standards
Equivalent dated standard
References as listed in the ISO
standard
EN ISO or IEC
a
ISO 10993-1 EN ISO 10993-1:2020 ISO 10993-1:2018
ISO 10993-5 EN ISO 10993-5:2009 ISO 10993-5:2009
ISO 10993- 17 EN ISO 10993-17: 2009 ISO 10993-17:2002
a
ISO 10993-18 EN ISO 10993-18:2020 ISO 10993-18:2020
a
Under preparation at European level.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 10993-12:2021 has been approved by CEN as EN ISO 10993-12:2021 without any
modification.
Annex ZA
(informative)
Relationship between this European standard and the General Safety and
Performance Requirements of Regulation (EU) 2017/745 aimed to be
covered
This European standard has been prepared under a Commission’s standardisation request to provide
one voluntary means of conforming to the General Safety and Performance Requirements of Regulation
(EU) 2017/745 of 5 April 2017 concerning medical devices [OJ L 117].
Once this standard is cited in the Official Journal of the European Union under that Regulation,
compliance with the normative clauses of this standard given in Table ZA.1 confers, within the limits of
the scope of this standard, a presumption of conformity with the corresponding General Safety and
Performance Requirements of that Regulation, and associated EFTA regulations.
NOTE 1 Where a reference from a clause of this standard to the risk management process is made, the risk
management process needs to be in compliance with Regulation (EU) 2017/745. This means that risks have to be
‘reduced as far as possible’, ‘reduced to the lowest possible level’, ‘reduced as far as possible and appropriate’,
‘removed or reduced as far as possible’, ‘eliminated or reduced as far as possible’, ’removed or minimized as far as
possible’, or ‘minimized’, according to the wording of the corresponding General Safety and Performance
Requirement.
NOTE 2 The manufacturer’s policy for determining acceptable risk must be in compliance with General Safety
and Performance Requirements 1, 2, 3, 4, 5, 8, 9, 10, 11, 14, 16, 17, 18, 19, 20, 21 and 22 of the Regulation.
NOTE 3 This Annex ZA is based on normative references according to the table of references in the European
Foreword, replacing the references in the core text.
NOTE 4 When a General Safety and Performance Requirement does not appear in Table ZA.1, it means that it is
not addressed by this European Standard.
Table ZA.1 — Correspondence between this European Standard and
Annex I of Regulation (EU) 2017/745 [OJ L 117]
General Safety and
Performance Requirements Clause(s)/sub-clause(s) of
Remarks/Notes
of Regulation this EN
(EU) 2017/745
10.2 is only partly covered by this
standard, since the standard does not
provide requirements on design and
manufacture and does not oblige to
minimize risk.
However, this standard provides a
means of preparing samples to assess
conformity with this part of this general
10.2 (first sentence only) 4, 5, 6, 7, 8, 9, 10 and 11
health and safety requirment in
conjunction with other relevant parts of
ISO 10993 for the design and
manufacture of medical devices.
Packaging is not covered.
Risks from residues to person involved
in the transport or storage of medical
devices are not covered.
10.4.1 is only partly covered by this
standard, since the standard does not
provide requirements on design and
manufacture and does not oblige to
minimize risk.
However, this standard provides a
10.4.1 (First paragraph only) 4, 5, 6, 7, 8, 9, 10 and 11 means of preparing samples of medical
devices to assess conformity with this
part of this general health and safety
requirment in conjunction with other
relevant parts of ISO 10993.
Other forms of toxicity are not dealt
with in this standard.
WARNING 1 — Presumption of conformity stays valid only as long as a reference to this European
standard is maintained in the list published in the Official Journal of the European Union. Users of this
standard should consult frequently the latest list published in the Official Journal of the European
Union.
WARNING 2 — Other Union legislation may be applicable to the product(s) falling within the scope of
this standard.
INTERNATIONAL ISO
STANDARD 10993-12
Fifth edition
2021-01
Biological evaluation of medical
devices —
Part 12:
Sample preparation and reference
materials
Évaluation biologique des dispositifs médicaux —
Partie 12: Préparation des échantillons et matériaux de référence
Reference number
ISO 10993-12:2021(E)
©
ISO 2021
ISO 10993-12:2021(E)
© 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
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO 10993-12:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General requirements . 3
5 Reference materials (RMs) . 4
5.1 General . 4
5.2 Certification of RMs for biological safety testing . 4
6 Use of RMs as experimental controls . 4
7 Test sample selection . 5
8 Test sample and RM preparation . 5
9 Selection of representative portions from a medical device . 6
10 Preparation of extracts of samples . 6
10.1 General . 6
10.2 Containers for extraction . 6
10.3 Extraction conditions and methods . 7
10.4 Extraction conditions for materials that polymerize in situ .10
11 Records .10
Annex A (informative) Experimental controls .11
Annex B (informative) General principles on, and practices of, test sample preparation and
sample selection .13
Annex C (informative) Principles of test sample extraction .15
Annex D (informative) Exhaustive extraction of polymeric materials for biological evaluation .18
Bibliography .20
ISO 10993-12:2021(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 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/
is o/ f or ewor d . ht m l .
This document was prepared by Technical Committee ISO/TC 194, Biological and clinical evaluation of
medical devices, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 206, Biological and clinical evaluation of medical devices, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fifth edition cancels and replaces the fourth edition (ISO 10993-12:2012), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— change of scope to cover extractions only for biological evaluation tests;
— harmonization of definitions with ISO 10993-18;
— revision of 10.3.1 extraction condition table and Annex D regarding exhaustive extraction.
A list of all parts in the ISO 10993 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 2021 – All rights reserved

ISO 10993-12:2021(E)
Introduction
It is important that sample preparation methods be appropriate for both the biological evaluation
methods and the materials being evaluated. Each biological test method requires the selection of
materials, extraction solvents and conditions.
This document is based on existing national and international standards and regulations, wherever
possible.
INTERNATIONAL STANDARD ISO 10993-12:2021(E)
Biological evaluation of medical devices —
Part 12:
Sample preparation and reference materials
1 Scope
This document specifies requirements and gives guidance on the procedures in the preparation of
samples and the selection of reference materials for medical device testing primarily in biological test
systems primarily in accordance with one or more parts of the ISO 10993 series.
Specifically, this document addresses the following:
— test sample selection;
— selection of representative portions from a medical device;
— test sample preparation;
— experimental controls;
— selection of, and requirements for, reference materials;
— preparation of extracts.
This document is not applicable to live cells but can be relevant to the material or medical device
components of combination products containing live cells.
Extractions for chemical characterization are covered in ISO 10993-18. Clause 7, 8, 9, 10 [with the
exception of 10.3.5 and 10.3.11 b)], and 11 can apply to extractions for chemical characterization.
Information given in C.1 to C.4 can also be relevant.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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/
3.1
blank
extraction vehicle not containing the test material, which is exposed to identical vessels and conditions
as the test sample during extraction
Note 1 to entry: The purpose of the blank is to evaluate possible confounding effects due to the extraction vessel,
extraction vehicle and extraction process.
ISO 10993-12:2021(E)
3.2
CRM
certified reference material
reference material (RM) characterized by a metrologically valid procedure for one or more specified
properties, accompanied by an RM certificate that provides the value of the specified property, its
associated uncertainty, and a statement of metrological traceability
Note 1 to entry: The concept of value includes a nominal property or a qualitative attribute such as identity or
sequence. Uncertainties for such attributes may be expressed as probabilities or levels of confidence.
Note 2 to entry: Metrologically valid procedures for the production and certification of RMs are given in, among
others, ISO 17034 and ISO Guide 35.
Note 3 to entry: ISO Guide 31 gives guidance on the contents of RM certificates.
Note 4 to entry: ISO/IEC Guide 99:2007 has an analogous definition (5.14).
[SOURCE: ISO Guide 30:2015, 2.1.2]
3.3
exaggerated extraction
extraction that is intended to result in a greater amount of a chemical constituent being released as
compared to the amount generated under the simulated conditions of use
Note 1 to entry: It is important to ensure that the exaggerated extraction does not result in a chemical change of
the material.
3.4
exhaustive extraction
extraction conducted until the amount of extractable material in a subsequent extraction is less than
10 % by gravimetric analysis (or that achieved by other means) of that detected in the initial extraction
Note 1 to entry: As it is not possible to demonstrate the exhaustive nature of residual recovery, the definition of
exhaustive extraction adopted is as above. See also Annex C.
3.5
experimental control
substance with well-characterized responses, which is used in a specific test system to assist in
evaluating if the test system has responded in a reproducible and appropriate manner
3.6
extract
liquid that results from extraction of the test sample or control
3.7
extractable substance
substance that can be released from a medical device or material using either extraction solvents
or extraction conditions, or both, that are expected to be at least as aggressive as the conditions of
clinical use
3.8
homogeneity
consistency of a material's chemical and physical compositions, and uniformity in response to a
biological endpoint
Note 1 to entry: A reference material is said to be homogeneous if the biological response in a specific test is
found to lie within the specified uncertainty limits of the test, irrespective of the batch or lot of material from
which the test sample is extracted.
3.9
leachable substance
substance that can be released from a medical device or material during clinical use
2 © ISO 2021 – All rights reserved

ISO 10993-12:2021(E)
3.10
negative control
well-characterized material and/or substance, which, when tested by a specific procedure, demonstrates
the suitability of the procedure to yield a reproducible, appropriately negative, non-reactive or minimal
response in the test system
Note 1 to entry: In practice, negative controls are reference materials but can include blanks and extraction
vehicles/solvents.
3.11
positive control
well-characterized material and/or substance, which, when evaluated by a specific test method,
demonstrates the suitability of the test system to yield a reproducible, appropriately positive or reactive
response in the test system
3.12
reference material
RM
material, sufficiently homogeneous and stable with respect to one or more specified properties, which
has been established to be fit for its intended use in a measurement process
Note 1 to entry: RM is a generic term.
Note 2 to entry: Properties can be quantitative or qualitative, e.g. identity of substances or species.
Note 3 to entry: Uses may include the calibration of a measurement system, assessment of a measurement
procedure, assigning values to other materials, and quality control.
Note 4 to entry: ISO/IEC Guide 99:2007 has an analogous definition (5.13), but restricts the term “measurement”
to apply to quantitative values. However, Note 3 of ISO/IEC Guide 99:2007, 5.13 (VIM), specifically includes
qualitative properties, called “nominal properties”.
Note 5 to entry: The laboratory is to demonstrate that the simulated-use extraction is carried out under
conditions that provide an appropriate representation of intended use. Product-use simulation is carried out
assuming the medical device is assigned to the most stringent category possible for the duration of exposure and
takes into consideration both the tissue(s) exposed and the temperature of exposure.
[SOURCE: ISO Guide 30:2015, 2.1.1 — Note 5 to entry has been added.]
3.13
stability
characteristic of a material, when stored under specified conditions, to maintain a specified property
value within specified limits for a specified period of time
[5]
Note 1 to entry: See also the IUPAC Compendium of Analytical Nomenclature .
3.14
test sample
medical device, component or material (or a representative sample thereof, manufactured and
processed by equivalent methods), or an extract or portion thereof that is subjected to biological
evaluation testing
4 General requirements
When identifying hazards and estimating risk in relation to medical devices, hazards that arise from
changes in the manufacturing process, or insufficient control of the manufacturing process, shall be
considered in the design and preparation of test samples, as described in ISO 14971. Particular attention
shall be given to material additives, unintentional base material impurities and manufacturing process
residues, e.g. trace elements and cleaning and disinfection agents.
ISO 10993-12:2021(E)
The ISO 10993 series describes many different biological assay systems. Therefore, the individual parts
shall be consulted to ascertain whether these are appropriate for specific test systems.
Experimental controls shall be used in biological evaluations carried out in order to either validate a
test procedure or compare the results between materials, or both. Depending on the specifications of a
particular test, either negative controls, blanks or positive controls, or all three, shall be used.
NOTE The same type of control can be applicable to different tests and can allow cross-reference to other
established materials and test methods. Additional guidance on the selection of experimental controls is given in
Annex A. Use of positive controls for in vivo testing might be affected by animal welfare regulations.
5 Reference materials (RMs)
5.1 General
RMs are established by individual laboratories. The extent of chemical, physical and biological
characterization is determined by the individual laboratory. Commercially available articles may be
used as RMs.
NOTE See also ISO Guide 35.
CRMs are selected for their high purity, critical characteristics, suitability for the intended purpose and
general availability. The critical chemical, physical and biological characteristics shall be determined
by collaborative testing in three or more laboratories and made available to the investigator by the
distributor.
It is desirable for users to obtain a commitment from suppliers of RMs or CRMs stating that these
materials will be available to the user for at least five years. A second but less desirable option is for the
source of the RM or CRM to publish an “open formulation” for the material, i.e. publication of the source
materials and details of the processing needed to ensure uniform batches of the RM.
5.2 Certification of RMs for biological safety testing
Qualification of an RM is a procedure that establishes the numerical or qualitative value of the biological
response of the material under specified test conditions, ensuring reproducibility of the response either
within laboratories or between laboratories, or both. The range of biological responses associated with
the material shall be established through laboratory tests.
NOTE See also ISO 17034.
Suppliers of RMs shall certify the materials. The supplier determines the extent of chemical and physical
characterization that is performed. The individual laboratories that use the RM shall identify the
biological characterization necessary to qualify an RM for a specific test or procedure. Commercially
available materials may be used as RMs, provided they are certified and qualified.
Certification of a RM is a procedure that establishes the numerical or qualitative value of the biological
response of the material under the specified test conditions. This process serves to validate the testing
of the material for that particular response and results in the issuance of a certificate. The biological
response of the material shall be established through interlaboratory tests.
6 Use of RMs as experimental controls
RMs or CRMs shall be used in biological tests as control materials to demonstrate the suitability of
a procedure to yield a reproducible response, i.e. positive or negative, or both. Any material used in
this way shall be characterized with each biological test procedure for which the use of the material
is desired. A material characterized and then certified for one reference test method or response, for
4 © ISO 2021 – All rights reserved

ISO 10993-12:2021(E)
example, delayed-type hypersensitivity, shall not be used as an RM for another, for example, cytotoxicity,
without additional validation.
NOTE The use of an RM will facilitate the comparability of the response between laboratories and help
assess reproducibility of the test performance within individual laboratories. For comparison of the biological
response, it is desirable to use RMs having a range of responses, e.g. minimum, intermediate or severe.
RMs used as experimental controls shall meet the established quality assurance procedures of the
manufacturer and test laboratory. They shall be identified in relation to source, manufacturer, grade
and type. RMs are processed as described in Clause 8.
When RMs are used as experimental controls, they shall be in the same material class as the test
sample, i.e. polymer, ceramic, metal, colloid. However, pure chemicals may be used as experimental
controls for mechanistically-based test procedures, for example, genotoxicity and immune delayed-
type hypersensitivity assays.
7 Test sample selection
Testing shall be performed on the final product, representative samples from the final product,
materials processed in the same manner as the final product (see ISO 10993-1), or on appropriate
extracts of any of these. The choice of test sample shall be justified.
NOTE In the case of materials that cure in situ, different test samples representative of the cured material
versus the uncured state of the material might be needed.
For absorbable materials that could potentially have toxic degradants and residuals, testing of
intermediate products should be considered.
The same test sample selection procedure applies when an extract is required.
8 Test sample and RM preparation
Test samples and RMs shall be handled with care to prevent contamination. Any residue from the
manufacturing processes, intentional or unintentional additives or contaminants, shall be considered
integral to the medical device, medical device portion or component, or representative sample.
NOTE For additional guidance on preparation, see Annex B.
— Test samples from sterilized medical devices and RMs shall be handled aseptically, if appropriate to
the test procedure.
— Test samples which are clean, sterile and disinfected, shall be processed by the method recommended
by the manufacturer and handled aseptically, if appropriate to the test procedure.
— The influence of the cleaning process and cleaning agent shall be considered in the selection and
handling of the test sample.
Test samples from medical devices not required to be sterile in use shall be used as supplied and
handled aseptically throughout the test sample preparation. If sterile test samples are required for a
test procedure, e.g. for cytotoxicity testing, the effect of the sterilization or resterilization process on
the test sample and RM shall be considered.
When test samples and RMs need to be cut into pieces, as described in 10.3.3, the influence of previously
unexposed surfaces, e.g. lumens or cut surfaces shall be considered. Tools used for cutting medical
devices into representative portions for testing shall be cleaned between uses to prevent contamination.
Furthermore, care shall be taken that the tool itself doesn’t contaminate the device.
ISO 10993-12:2021(E)
9 Selection of representative portions from a medical device
9.1 If a medical device cannot be tested as a whole, each individual material in the final product that is
required to be tested shall be represented proportionally in the test sample.
— The test sample of the medical devices with surface coatings shall include both the coating material
and the substrate, even if the substrate has no tissue contact.
— The test sample shall include a representative portion of the joint or seal, or both, if adhesives,
radiofrequency (RF) seals or solvent seals are used in the manufacture of a portion of the medical
device which comes into contact with patients.
9.2 Composite materials shall be tested as finished materials.
9.3 When different materials are present in a single medical device, the potential for synergies and
interactions shall be considered in the choice of test sample.
9.4 The test sample shall be chosen to maximize the exposure of the test system to the components of
a medical device that are known to have potential for a biological response.
9.5 Non-patient contacting portions of the medical device should, if possible, be excluded either
physically from test sample extracts or by exclusion of the surface area in the calculation of the extraction
ratio. When this is not possible, the extraction ratio shall be justified. Ensure that all contacting portions
are covered by the selected extraction vehicle volume.
Clinician and user surface contact with materials other than those in common use in consumer products
with a similar nature of contact, should be considered [see ISO 10993-1:2018, 5.2.2, a)].
9.6 Medical device components with different type or duration of tissue contact might need to be
extracted and tested separately.
10 Preparation of extracts of samples
10.1 General
If extracts of the medical device are required for a test procedure, the extraction vehicles and conditions
of extraction used shall be appropriate to the nature and use of the final product and to the purpose of
the test, for example, hazard identification, risk estimation or risk assessment. The physico-chemical
properties of the medical device materials, leachable substances or residues shall be considered when
choosing the extraction conditions (see ISO 10993-18 and ISO/TS 10993-19). For more information on
sample preparation for testing of nanomaterials or nanostructured materials, see ISO/TR 10993-22.
NOTE For additional guidance on the extraction of samples, see Annex C.
10.2 Containers for extraction
The extraction shall be performed in clean, chemically inert, closed containers with minimum dead space.
To ensure that the extraction vessels do not adulterate the extract of the test sample, the extraction
vessels shall be either borosilicate glass tubes with caps having an inert liner, for example,
polytetrafluoroethylene or other inert extraction vessels, as required for either specific materials or
extraction procedures, or both.
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ISO 10993-12:2021(E)
10.3 Extraction conditions and methods
10.3.1 Extraction conditions are based on common practice and are justified on the basis of providing
a standardized approach that is, in many ways, an appropriate exaggeration of product use. Extraction
shall be conducted under one of the following conditions (see also C.5):
a) (37 ± 1) °C for (24 ± 2) h;
b) (37 ± 1) °C for (72 ± 2) h;
c) (50 ± 2) °C for (72 ± 2) h;
d) (70 ± 2) °C for (24 ± 2) h;
e) (121 ± 2) °C for (1 ± 0,1) h.
Extraction at (37 ± 1) °C for (24 ± 2) h is acceptable for cytotoxicity testing of limited-contact medical
devices. For medical devices which are in limited contact with intact skin or mucosa and which are
not implanted, extraction times of less than 24 h, but not less than 4 h, are acceptable for cytotoxicity
testing (see ISO 10993-5). For medical devices which are in prolonged (>24 h to 30 d) or long-term
contact (>30 d), extraction times of 72 h are recommended for cytotoxicity testing because extraction
for 24 h may not be sufficient to obtain an extract that represents the chemicals released beyond
24 h of device use. In such cases, all controls including the negative, positive, and the reagent (i.e. cell
culture medium alone) controls shall be incubated for 72 h. However, if there are data available for the
prolonged or long-term tissue-contacting devices which demonstrate that 24 h extraction is sufficient
to release extractables/leachables from the device and extending the extraction time to 72 h does not
result in release of additional chemicals from the device, the 24 h extraction is sufficient. For extraction
in tissue culture medium with serum, extraction temperatures greater than (37 ± 1) °C can adversely
impact either the chemistry of the serum or the stability of the serum, or both, and other constituents
in the culture medium.
The extraction conditions described above, which have been used to provide a measure of the hazard
potential for the risk estimation of the medical device or material, are based on historical precedent.
Other conditions that simulate the leachables occurring during clinical use, or that provide an adequate
measure of the hazard potential may be used but shall be described and justified.
Extraction is a complex process influenced by many factors e.g. time, temperature, surface-area-to-
volume ratio, the extraction vehicle and the phase equilibrium of the material. For specific products,
other factors can also have an influence. The effects of higher temperatures or other conditions on
extraction kinetics and the identity of the extraction vehicle(s) should be considered carefully if
exaggerated extraction is used.
The phase equilibrium of a material during extraction controls the relative amounts of amorphous and
crystalline phases present. For the amorphous phase, the glass transition temperature, T , dictates the
g
polymer chain mobility and the diffusion rate in the phase. Usually, at temperatures higher than T ,
g
the diffusion rate is considerably higher compared with that below T . The diffusion rate is lowest in
g
the crystalline phase. The extraction conditions should not alter the phase equilibrium of the material.
Phase alteration can affect the amount and type of extractables.
For example, two possibilities exist when elevated temperatures are used:
— the energy of the increased temperature can cause either increased cross-linking or polymerization
of the polymer, or both, and, therefore, decrease the amount of free monomer that is available to
migrate from the polymer;
— the increased temperature can cause degradation products to form that are not typically found in
the finished medical device under conditions of use.
10.3.2 For materials that are intended to dissolve or absorb under conditions of use, the selection of
extraction conditions described in 10.3 might need to consider the thermal properties (e.g. glass transition
ISO 10993-12:2021(E)
temperature of polymers) of device materials of construction and the relevant clinical use conditions. For
these materials, the extracts prepared based on 10.3 may have changes either in osmolarities or in the
pH that may not be appropriate for the test system to be dosed. Any adjustment applied to the extracts
prior to biocompatibility testing should be justified.
NOTE For more information on sample preparation for testing of absorbable medical devices, see
ISO 10993-3, ISO 10993-6, ISO 10993-13, ISO 10993-14, ISO 10993-15, ISO 10993-18 and ISO/TS 37137-1.
Perform extraction using the appropriate extraction vehicle and the conditions of time and temperature
to simulate exaggerated exposure wherever possible. Complete dissolution using the extraction vehicles
and conditions recommended by this document can be appropriate, if justified; however, caution should
be taken since complete device dissolution can create challenges for subsequent biological testing
(e.g. difficulty in dosing animals with neat test extract if viscosity is increased, difficulty in interpreting
in vitro cell-based test failure data in case of increased osmolality or pH change). For chemical
characterization and hazard assessment of potential intermediate degradants that cannot otherwise
be evaluated under these testing conditions, see ISO 10993-17 and ISO 10993-18.
10.3.3 The standard surface area can be used to determine the volume of extraction vehicle needed.
This area includes the combined area of all tissue contacting surfaces of the sample and ignores the
contribution of indeterminate surface irregularities. When the surface area cannot be determined due to
configuration of the sample, a mass/volume of extracting fluid shall be used. See Table 1.
Other surface-area-to-volume extraction ratios, for example, those related to evaluation of porous
materials can be used if they simulate
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