SIST EN 62321-7-1:2016
(Main)Determination of certain substances in electrotechnical products - Part 7-1: Determination of the presence of hexavalent chromium (Cr(VI)) in colorless and colored corrosion-protected coatings on metals by the colorimetric method
Determination of certain substances in electrotechnical products - Part 7-1: Determination of the presence of hexavalent chromium (Cr(VI)) in colorless and colored corrosion-protected coatings on metals by the colorimetric method
This part of IEC 62321 describes a boiling water extraction procedure intended to provide a
qualitative determination of the presence of hexavalent chromium (Cr(VI)) in colourless and
coloured corrosion-protection coatings on metallic samples.
Due to its highly reactive nature, the concentration of Cr(VI) in a corrosion-protection coating
can change drastically with time and storage conditions. Since storage conditions prior to
sample submission are not often known or provided with the samples, this procedure
determines the presence of Cr(VI) based on the levels detected in the coatings at the time of
testing. For testing of freshly coated samples, a minimum waiting period of 5 days (after the
coating process) is necessary to ensure the coatings have stabilized. This waiting period
allows potential post-process oxidation of Cr(III) to Cr(VI) to occur prior to testing.
The presence of Cr(VI) is determined by the mass of Cr(VI) per surface area of the coating,
in μg/cm2. This approach is preferred since corrosion-protection coating weights are often
difficult to measure accurately after production. From a coating technology perspective, the
industry as a whole has transitioned to either using the non-Cr(VI) based chemistries – where
little to no Cr(VI) should be present – or using the traditional Cr(VI) based chemistries –
where significant levels of Cr(VI) are present and can be detected reliably. Given this industry
shift, the presence or absence of Cr(VI) is often sufficient for compliance testing purposes.
In this procedure, when Cr(VI) in a sample is detected below the 0,10 μg/cm2 LOQ (limit of
quantification), the sample is considered to be negative for Cr(VI). Since Cr(VI) may not be
uniformly distributed in the coating even within the same sample batch, a “grey zone” between
0,10 μg/cm2 and 0,13 μg/cm2 has been established as “inconclusive” to reduce inconsistent
results due to unavoidable coating variations. In this case, additional testing may be
necessary to confirm the presence of Cr(VI). When Cr(VI) is detected above 0,13 μg/cm2, the
sample is considered to be positive for the presence of Cr(VI) in the coating layer.
Verfahren zur Bestimmung von bestimmten Substanzen in Produkten der Elektrotechnik - Teil 7-1: Bestimmung des Vorliegens von sechswertigem Chrom (Cr(VI)) in farblosen und farbigen Korrosionsschutzüberzügen auf Metallen durch das kolorimetrische Verfahren
Détermination de certaines substances dans les produits électrotechniques - Partie 7-1: Chrome hexavalent - Présence de chrome hexavalent (Cr(VI)) dans les revêtements incolores et colorés de protection anticorrosion appliqués sur les métaux à l'aide de la méthode colorimétrique
L'IEC 62321-7-1:2015 décrit une procédure d'extraction à l'eau bouillante destinée à assurer une détermination qualitative de la présence de chrome hexavalent (Cr(VI)) dans les revêtements incolores et colorés de protection anticorrosion d'échantillons métalliques. Dans la présente procédure, lorsque du chrome hexavalent est détecté sur un échantillon selon une valeur inférieure à 0,10 g/cm2 de la limite de quantification (LOQ), l'échantillon est considéré comme négatif au chrome hexavalent. Dans la mesure où le chrome hexavalent peut ne pas être uniformément réparti sur le revêtement, et ce même au sein du même lot d'échantillons, une "zone grise" comprise entre 0,10 g/cm2 et 0,13 g/cm2 a été établie comme "non concluante" pour réduire l'incohérence des résultats due à des variations inévitables de revêtement. Dans ce cas, des essais supplémentaires peuvent être nécessaires pour confirmer la présence de chrome hexavalent. Si du chrome hexavalent est détecté selon une valeur supérieure à 0,13 g/cm2, l'échantillon est considéré comme positif dans le cadre de la présence de chrome hexavalent dans la couche de revêtement.
Določevanje posameznih substanc v elektrotehniških izdelkih - 7-1. del: Ugotavljanje prisotnosti šestvalentnega kroma (Cr(VI)) v brezbarvnih in obarvanih protikorozijskih premazih na kovinah s kolorimetrično metodo
Ta del standarda IEC 62321 opisuje postopek ekstrakcije z vrelo vodo, namenjen za kvalitativno ugotavljanje prisotnosti šestvalentnega kroma (Cr(VI)) v brezbarvnih in obarvanih protikorozijskih premazih na kovinskih vzorcih.
Koncentracija Cr(VI) v obarvanem protikorozijskem premazu se lahko zaradi izredne reaktivnosti bistveno spremeni, odvisno od časa in pogojev shranjevanja. Ker podatki o pogojih shranjevanja pred predložitvijo vzorca običajno niso znani ali so priloženi vzorcem, ta postopek določa prisotnost Cr(VI) na podlagi zaznanih ravni v premazih v času preskušanja. Pri preskušanju sveže premazanih vzorcev je treba upoštevati čakalno dobo najmanj 5 dni (po nanosu premaza), da se premazi ustrezno stabilizirajo. Ta čakalna doba omogoča, da se pred preskušanjem izvede morebitna poprocesna oksidacija Cr(III) v Cr(VI). Prisotnost Cr(VI) je določena na podlagi mase Cr(VI) glede na površino premaza (μg/cm2). Ta pristop se priporoča, ker je težo protikorozijskega premaza po proizvodnji
težko natančno izmeriti. Z vidika tehnologije premazov je celotna industrija prešla na uporabo kemikalij brez Cr(VI) (s prisotnostjo majhnih količin Cr(VI) ali brez Cr(VI)) ali uporabo običajnih kemikalij na osnovi Cr(VI) (s prisotnostjo večjih količin Cr(VI), ki jih je mogoče zanesljivo zaznati). Na podlagi tega prehoda industrije je prisotnost ali odsotnost Cr(VI) običajno zadosten dejavnik za namene preskušanja skladnosti. Če je zaznana raven Cr(VI) v vzorcu pri tem postopku pod 0,10 μg/cm2 LOQ (meja kvantifikacije), se vzorec obravnava kot negativen za Cr(VI). Ker Cr(VI) v premazu morda ni enakomerno porazdeljen (celo v isti seriji vzorcev), je bilo »sivo območje« z vrednostmi med 0,10 μg/cm2 in 0,13 μg/cm2 označeno kot »nedoločeno«, da se zmanjša število nedoslednih rezultatov zaradi neizogibnih razlik v sestavi premazov. V tem primeru bo morda treba opraviti dodatno preskušanje, da se potrdi prisotnost Cr(VI). Če je zaznana raven Cr(VI) nad 0,13 μg/cm2, se vzorec obravnava kot pozitiven za prisotnost Cr(VI) v sloju premaza.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 62321-7-1:2016
01-marec-2016
'RORþHYDQMHSRVDPH]QLKVXEVWDQFYHOHNWURWHKQLãNLKL]GHONLKGHO
8JRWDYOMDQMHSULVRWQRVWLãHVWYDOHQWQHJDNURPD &U 9, YEUH]EDUYQLKLQREDUYDQLK
SURWLNRUR]LMVNLKSUHPD]LKQDNRYLQDKVNRORULPHWULþQRPHWRGR
Determination of certain substances in electrotechnical products - Part 7-1:
Determination of the presence of hexavalent chromium (Cr(VI)) in colorless and colored
corrosion-protected coatings on metals by the colorimetric method
Ta slovenski standard je istoveten z: EN 62321-7-1:2015
ICS:
29.020 Elektrotehnika na splošno Electrical engineering in
general
31.020 Elektronske komponente na Electronic components in
splošno general
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
SIST EN 62321-7-1:2016 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 62321-7-1:2016
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SIST EN 62321-7-1:2016
EUROPEAN STANDARD EN 62321-7-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2015
ICS 13.020; 43.040.10
English Version
Determination of certain substances in electrotechnical products
- Part 7-1: Determination of the presence of hexavalent
chromium (Cr(VI)) in colorless and colored corrosion-protected
coatings on metals by the colorimetric method
(IEC 62321-7-1:2015)
Détermination de certaines substances dans les produits Verfahren zur Bestimmung von bestimmten Substanzen in
électrotechniques - Partie 7-1: Chrome hexavalent - Produkten der Elektrotechnik - Teil 7-1: Bestimmung des
Présence de chrome hexavalent (Cr(VI)) dans les Vorliegens von sechswertigem Chrom (Cr(VI)) in farblosen
revêtements incolores et colorés de protection anticorrosion und farbigen Korrosionsschutzüberzügen auf Metallen
appliqués sur les métaux à l'aide de la méthode durch das kolorimetrische Verfahren
colorimétrique (IEC 62321-7-1:2015)
(IEC 62321-7-1:2015)
This European Standard was approved by CENELEC on 2015-10-21. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 62321-7-1:2015 E
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SIST EN 62321-7-1:2016
EN 62321-7-1:2015
European foreword
The text of document 111/380/FDIS, future edition 1 of IEC 62321-7-1, prepared by
IEC/TC 111 "Environmental standardization for electrical and electronic products and systems" was
submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 62321-7-1:2015.
The following dates are fixed:
(dop) 2016-07-21
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2018-10-21
standards conflicting with the
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 62321-7-1.2015 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
ISO 3613 NOTE Harmonized as EN ISO 3613.
ISO 648 NOTE Harmonized as EN ISO 648.
DIN EN 15205:2007 NOTE Harmonized as EN 15205:2006.
2
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SIST EN 62321-7-1:2016
EN 62321-7-1:2015
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 62321-1 - Determination of certain substances in EN 62321-1 -
electrotechnical products -- Part 1:
Introduction and overview
IEC 62321-2 - Determination of certain substances in EN 62321-2 -
electrotechnical products -- Part 2:
Disassembly, disjunction and mechanical
sample preparation
ISO 78-2 - Chemistry_- Layouts for standards_- - -
Part_2: Methods of chemical analysis
ISO 3696 - Water for analytical laboratory use - EN ISO 3696 -
Specification and test methods
3
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SIST EN 62321-7-1:2016
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SIST EN 62321-7-1:2016
IEC 62321-7-1
®
Edition 1.0 2015-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Determination of certain substances in electrotechnical products –
Part 7-1: Hexavalent chromium – Presence of hexavalent chromium (Cr(VI)) in
colourless and coloured corrosion-protected coatings on metals by the
colorimetric method
Détermination de certaines substances dans les produits électrotechniques –
Partie 7-1: Chrome hexavalent – Présence de chrome hexavalent (Cr(VI)) dans
les revêtements incolores et colorés de protection anticorrosion appliqués sur
les métaux à l'aide de la méthode colorimétrique
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.020; 43.040.10 ISBN 978-2-8322-2895-1
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN 62321-7-1:2016
– 2 – IEC 62321-7-1:2015 © IEC 2015
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviations . 7
3.1 Terms and definitions . 7
3.2 Abbreviations . 7
4 Reagents . 7
4.1 General . 7
4.2 Reagents . 7
5 Apparatus . 7
5.1 General . 7
5.2 Apparatus . 7
6 Sampling . 8
7 Boiling water extraction procedure . 8
8 Calibration . 11
8.1 Permanent calibration instruments . 11
8.2 Traditional calibration instruments . 11
9 Calculation . 11
10 Precision . 12
11 Quality assurance and control . 12
11.1 Colorimetric instrument performance verification . 12
11.2 Limits of detection (LOD) and limits of quantification (LOQ) . 12
12 Test report . 13
Annex A (informative) International inter-laboratory study on corrosion-protected
coatings – Data overview . 16
Bibliography . 18
Figure 1 – Screw body and screw head measurements . 9
Figure A.1 – Concentration of chromium VI based on surface area for all samples . 16
Figure A.2 – Concentration of chromium VI based on surface area – Expanded view
2 2
between 0 µg/cm to 1 µg/cm . 17
Table 1 – Comparison to standard solution and interpretation of results . 11
Table 2 – Student’s t values used for calculation of method detection limit (LOD or
MDL = t-statistic × standard deviation (sn-1)) . 13
Table 3 – Reporting table . 14
Table 4 – Example of a completed reporting table . 15
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SIST EN 62321-7-1:2016
IEC 62321-7-1:2015 © IEC 2015 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DETERMINATION OF CERTAIN SUBSTANCES
IN ELECTROTECHNICAL PRODUCTS –
Part 7-1: Hexavalent chromium – Presence of hexavalent chromium (Cr(VI))
in colourless and coloured corrosion-protected coatings
on metals by the colorimetric method
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62321-7-1 has been prepared by IEC technical committee 111:
Environmental standardization for electrical and electronic products and systems.
The first edition of IEC 62321:2008 was a 'stand-alone' standard that included an introduction,
an overview of test methods, a mechanical sample preparation as well as various test method
clauses.
This first edition of IEC 62321-7-1 is a partial replacement of IEC 62321:2008, forming a
structural revision and generally replacing informative Annex B.
Future parts in the IEC 62321 series will gradually replace the corresponding clauses in
IEC 62321:2008. Until such time as all parts are published, however, IEC 62321:2008 remains
valid for those clauses not yet re-published as a separate part.
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SIST EN 62321-7-1:2016
– 4 – IEC 62321-7-1:2015 © IEC 2015
The text of this standard is based on the following documents:
FDIS Report on voting
111/380/FDIS 111/393/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62321 series can be found on the IEC website under the general
title: Determination of certain substances in electrotechnical products.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
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SIST EN 62321-7-1:2016
IEC 62321-7-1:2015 © IEC 2015 – 5 –
INTRODUCTION
The widespread use of electrotechnical products has drawn increased attention to their impact
on the environment. In many countries this has resulted in the adaptation of regulations
affecting wastes, substances and energy use of electrotechnical products.
The use of certain substances (e.g. lead (Pb), cadmium (Cd) and polybrominated
diphenylethers (PBDE’s)) in electrotechnical products is a source of concern in current and
proposed regional legislation.
The purpose of the IEC 62321 series is therefore to provide test methods that will allow the
electrotechnical industry to determine the levels of certain substances of concern in
electrotechnical products on a consistent global basis.
WARNING – Persons using this International Standard should be familiar with normal
laboratory practice. This standard 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 and to ensure compliance with any national
regulatory conditions.
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DETERMINATION OF CERTAIN SUBSTANCES
IN ELECTROTECHNICAL PRODUCTS –
Part 7-1: Hexavalent chromium – Presence of hexavalent chromium (Cr(VI))
in colourless and coloured corrosion-protected coatings
on metals by the colorimetric method
1 Scope
This part of IEC 62321 describes a boiling water extraction procedure intended to provide a
qualitative determination of the presence of hexavalent chromium (Cr(VI)) in colourless and
coloured corrosion-protection coatings on metallic samples.
Due to its highly reactive nature, the concentration of Cr(VI) in a corrosion-protection coating
can change drastically with time and storage conditions. Since storage conditions prior to
sample submission are not often known or provided with the samples, this procedure
determines the presence of Cr(VI) based on the levels detected in the coatings at the time of
testing. For testing of freshly coated samples, a minimum waiting period of 5 days (after the
coating process) is necessary to ensure the coatings have stabilized. This waiting period
allows potential post-process oxidation of Cr(III) to Cr(VI) to occur prior to testing.
The presence of Cr(VI) is determined by the mass of Cr(VI) per surface area of the coating,
2
in µg/cm . This approach is preferred since corrosion-protection coating weights are often
difficult to measure accurately after production. From a coating technology perspective, the
industry as a whole has transitioned to either using the non-Cr(VI) based chemistries – where
little to no Cr(VI) should be present – or using the traditional Cr(VI) based chemistries –
where significant levels of Cr(VI) are present and can be detected reliably. Given this industry
shift, the presence or absence of Cr(VI) is often sufficient for compliance testing purposes.
2
In this procedure, when Cr(VI) in a sample is detected below the 0,10 µg/cm LOQ (limit of
quantification), the sample is considered to be negative for Cr(VI). Since Cr(VI) may not be
uniformly distributed in the coating even within the same sample batch, a “grey zone” between
2 2
0,10 µg/cm and 0,13 µg/cm has been established as “inconclusive” to reduce inconsistent
results due to unavoidable coating variations. In this case, additional testing may be
2
necessary to confirm the presence of Cr(VI). When Cr(VI) is detected above 0,13 µg/cm , the
sample is considered to be positive for the presence of Cr(VI) in the coating layer.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 62321-1, Determination of certain substances in electrotechnical products – Part 1:
Introduction and overview
IEC 62321-2, Determination of certain substances in electrotechnical products – Part 2:
Disassembly, disjointment and mechanical sample preparation
ISO 78-2, Chemistry – Layouts for standards – Part 2: Methods of chemical analysis
ISO 3696, Water for analytical laboratory use – Specification and test methods
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IEC 62321-7-1:2015 © IEC 2015 – 7 –
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62321-1 apply.
3.2 Abbreviations
For the purposes of this document, the abbreviations given in IEC 62321-1 apply.
4 Reagents
4.1 General
Use only reagents of recognized analytical grade, unless otherwise specified.
4.2 Reagents
The following reagents shall be used:
a) 1,5-diphenylcarbazide, analytical reagent grade.
b) Potassium dichromate (K Cr O ) stock solution: in a glass container, weigh (5.2 a)) and
2 2 7
dissolve 0,113 g of K Cr O (analytical reagent grade, dried at 100 °C for 1 h before use)
2 2 7
in water (4.2 f)) and dilute with water (4.2 f)) to the mark of a 1,000 ml volumetric flask
(5.2 e)). Cap or stopper the container tightly. The shelf life of this solution is one year.
2
Cr O ) equivalent comparison standard solutions, 0,10 µg/cm
c) Potassium dichromate (K
2 2 7
2
and 0,13 µg/cm : in this method, the 0,10 µg/ml and 0,13 µg/ml standards are equivalent
2 2 2
to 0,10 µg/cm and 0,13 µg/cm , respectively. Prepare the 0,10 µg/cm equivalent
comparison standard by pipetting (5.2 f)) 2,5 ml of the K Cr O stock solution (4.2 b)) into
2 2 7
2
a 1,000 ml volumetric flask and dilute to mark. Prepare the 0,13 µg/cm comparison
standard by pipetting (5.2 f)) 3,3 ml of the K Cr O stock solution (4.2 b)) into a 1,000 ml
2 2 7
volumetric flask (5.2 e)) and dilute to mark.
d) Acetone, analytical reagent grade.
e) Orthophosphoric acid (H PO ) solution (mass fraction of 75 %), analytical reagent grade.
3 4
f) Water: Grade 1 specified in ISO 3696, which shall be free of interferences.
5 Apparatus
5.1 General
All re-usable labware (glass, quartz, polyethylene, polytetrafluoroethylene (PTFE), etc.)
including the sample containers shall be soaked overnight in laboratory-grade detergent and
water, rinsed with water, and soaked for 4 h or more in HNO (volume fraction of 20%) or in a
3
mixture of dilute acids (HNO :HCl:H O = 1:2:9 by volume) followed by rinsing with water (4.2
3 2
f)). Alternative cleaning procedures are permitted, provided adequate cleanliness can be
demonstrated through the analysis of method blanks.
5.2 Apparatus
The following items shall be used for the analysis:
a) Analytical balance with an accuracy of 0,10 mg.
b) Thermometer or other temperature measurement device capable of measuring up to
100 °C.
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c) Colorimetric instrument: either a spectrophotometer for use at 540 nm providing a light
path of 1 cm or longer; or a filter photometer providing a light path of 1 cm or longer and
equipped with a greenish-yellow filter having maximum transmittance near 540 nm.
d) Boiling chips.
e) Volumetric glassware: Class A or equivalent of acceptable precision and accuracy.
Alternative volumetric equipment (e.g. automatic dilutors) with equivalent precision and
accuracy can be used.
f) Assorted calibrated pipettes: Class A glassware or other with equivalent precision and
accuracy.
g) Borosilicate glass or quartz beaker with a volume graduation of 250 ml, or equivalent.
h) Heating device: capable of maintaining boiling of the extraction solution.
i) Filter membranes (0,45 µm), cellulose-based or polycarbonate types preferred.
j) Silicon carbide (SiC) grinding paper with 800 grit size, or equivalent.
k) Watch glass.
6 Sampling
Samples shall not be stored in environments where oxidation of Cr(III) to Cr(VI) can occur.
Samples shall be stored at ambient conditions upon arrival until the start of testing. Ambient
conditions are defined as 45 % RH to 75 % RH (relative humidity) and temperature between
15 °C and 35 °C.
In some cases, disassembly or mechanical disjointment may be necessary to obtain samples
for testing; refer to IEC 62321-2 for sample preparation.
Prior to the test, the sample surface shall be free of all contaminants, fingerprints and stains.
If the surface is coated with thin oil, the oil shall be removed prior to the test by using a clean,
soft laboratory wipe wetted with a suitable solvent, or by rinsing the surface with a suitable
solvent at ambient temperature. The samples shall not be subject to forced drying at
temperature in excess of 35 °C. Treatment in alkaline solutions shall not be performed as
corrosion-protection coatings are broken down by alkalis.
If there is a polymer coating on a sample surface, gentle abrasion with a fine grinding paper
(5.2 j)) may be performed to expose the corrosion protection layer for extraction; however,
care shall be taken not to remove the entire corrosion protection coating beneath the polymer
coating. Other top coat removal methods may be applied if they are shown to be of equal or
greater effectiveness.
Since Cr(VI) is toxic to human beings, all potential Cr(VI)-containing samples and reagents
used in the method shall be handled with appropriate precautions. Solutions or waste material
containing Cr(VI) shall be disposed of properly. For example, ascorbic acid or other reducing
agents can be used to reduce Cr(VI) to Cr(III) prior to disposal.
7 Boiling water extraction procedure
The boiling water extraction procedure is as follows:
a) Prepare the test solution as follows: dissolve 0,5 g of diphenylcarbazide (4.2 a)) in 50 ml
of acetone (4.2 d)). Dilute slowly, while stirring, with 50 ml of water (4.2 f)) (rapid mixing
may result in precipitation of diphenylcarbazide). For maximum stability, store this test
solution under refrigeration at 7 °C ± 2 °C in an amber glass bottle. Discard when the
solution becomes discoloured.
2 2
b) The sample to be tested should have a surface area of 50 cm ± 5 cm . For fasteners or
samples with smaller surface area, use a suitable number of samples to obtain the total
2 2
required surface area. In cases where obtaining a total surface area of 50 cm ± 5 cm is
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SIST EN 62321-7-1:2016
IEC 62321-7-1:2015 © IEC 2015 – 9 –
not possible, a reduced total sample surface area may be used by reducing the water
extraction volume, while maintaining the same surface area to extraction volume ratio
2 2
(1 cm :1 ml). A minimum surface area of 25 cm is recommended. Similarly, a higher
sample surface area can be used by keeping the same ratio. The type of adjustment shall
be recorded in the final report.
The surface area of complex geometry samples can be estimated according to its
manufacturing specifications (e.g. mechanical drawings) if available, or by using its
dimensions and shape. For example: a flat-headed countersunk screw may be considered
as one metal cylinder (the screw body) adjacent to one metal cone (the screw head), as
shown in Figure 1.
H H
h b
IEC
Figure 1 – Screw body and screw head measurements
Estimated surface area of the screw body:
2
S = 2π R H + π(R ) (1)
b b b b
where
S is the estimated surface area of the screw body;
b
R is the radius of the screw body;
b
H is the height of the screw body.
b
Estimated surface area of the screw head:
2 2 2
S =πR (H +R ) +πR (2)
h h h h h
where
S is the estimated surface area of the screw head;
h
R is the top radius of the screw head;
h
H is the height of the screw head.
h
Total estimated surface area of the screw:
S = S + S (3)
...
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