prEN ISO 11426
(Main)Jewellery and precious metals - Determination of gold - Cupellation method (fire assay) (ISO/DIS 11426:2020)
Jewellery and precious metals - Determination of gold - Cupellation method (fire assay) (ISO/DIS 11426:2020)
Schmuck und Edelmetalle - Bestimmung von Gold - Dokimastisches Verfahren (ISO/DIS 11426:2020)
Dieses Dokument legt ein dokimastisches Verfahren (Kupellationsverfahren) zur Bestimmung von Gold in Materialien, die als homogen betrachtet werden, fest. Der Goldgehalt der Legierung sollte vorzugsweise zwischen 100 Promille und 999,5 Promille (‰) liegen. Feingehalte über 999,5 ‰ können durch eine spektroskopisches Differenzverfahren (z. B. ISO 15093) bestimmt werden.
Das Verfahren ist anwendbar für die meisten Arten von Goldproben. Einige Modifikationen sind für bestimmte Fälle angegeben (Vorhandensein einer großen Menge unedler Metalle, Platin oder Palladium, Silber). Es ist nicht kompatibel mit dem Vorhandensein von Iridium, Rhodium und Ruthenium über den Spuren (mehr als 0,25 ‰ für die Summe aller drei Elemente).
Dieses Verfahren ist als empfohlenes Verfahren zur Bestimmung der Feinheit von Schmucklegierungen nach ISO 9202 vorgesehen.
Joaillerie, bijouterie et métaux précieux - Dosage de l'or - Méthode de coupellation (essai au feu) (ISO/DIS 11426:2020)
Nakit in plemenite kovine - Določevanje zlata - Odtopitev primesi v tekočem svincu (ISO/DIS 11426:2020)
General Information
RELATIONS
Standards Content (sample)
SLOVENSKI STANDARD
oSIST prEN ISO 11426:2020
01-oktober-2020
Nakit in plemenite kovine - Določevanje zlata - Odtopitev primesi v tekočem svincu
(ISO/DIS 11426:2020)Jewellery and precious metals - Determination of gold - Cupellation method (fire assay)
(ISO/DIS 11426:2020)Schmuck und Edelmetalle - Bestimmung von Gold - Dokimastisches Verfahren (ISO/DIS
11426:2020)Joaillerie, bijouterie et métaux précieux - Dosage de l'or - Méthode de coupellation (essai
au feu) (ISO/DIS 11426:2020)Ta slovenski standard je istoveten z: prEN ISO 11426
ICS:
39.060 Nakit Jewellery
oSIST prEN ISO 11426:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 11426:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 11426
ISO/TC 174 Secretariat: DIN
Voting begins on: Voting terminates on:
2020-08-25 2020-11-17
Jewellery and precious metals — Determination of gold —
Cupellation method (fire assay)
ICS: 39.060
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
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Reference number
NATIONAL REGULATIONS.
ISO/DIS 11426:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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oSIST prEN ISO 11426:2020
ISO/DIS 11426:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 11426:2020
ISO/DIS 11426:2020(E)
Contents Page
Foreword ........................................................................................................................................................................................................................................iv
1 Scope ................................................................................................................................................................................................................................. 1
2 Normative references ...................................................................................................................................................................................... 1
3 Terms and definitions ..................................................................................................................................................................................... 1
4 Principle ........................................................................................................................................................................................................................ 2
5 Reagents ........................................................................................................................................................................................................................ 2
6 Apparatus ..................................................................................................................................................................................................................... 2
7 Sampling ........................................................................................................................................................................................................................ 3
8 Procedure..................................................................................................................................................................................................................... 3
8.1 Method selection ................................................................................................................................................................................... 3
8.2 General method ...................................................................................................................................................................................... 3
8.2.1 Assay samples .................................................................................................................................................................... 3
8.2.2 Proof samples ..................................................................................................................................................................... 4
8.2.3 Cupellation and treatment of precious metal buttons .................................................................... 4
8.2.4 Parting of the silver/gold samples ................................................................................................................... 4
8.2.5 Parting in individual flasks...................................................................................................................................... 4
8.2.6 Parting in a basket .......................................................................................................................................................... 4
8.3 Sample with large amount of base metals....................................................................................................................... 5
8.4 Sample containing platinum or palladium...................................................................................................................... 5
8.5 Sample with a silver/gold ratio higher than 3 ............................................................................................................. 5
9 Calculation and expression of results ............................................................................................................................................. 6
9.1 Proof sample factor ............................................................................................................................................................................. 6
9.2 Calculation of gold content ........................................................................................................................................................... 6
9.3 Repeatability ............................................................................................................................................................................................. 6
10 Test report ................................................................................................................................................................................................................... 6
Annex A (informative) Concentration of other metals, affecting the gold result ...................................................8
Bibliography ................................................................................................................................................................................................................................ 9
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oSIST prEN ISO 11426:2020
ISO/DIS 11426:2020(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 174, Jewellery and precious metals.
This fourth edition cancels and replaces the third edition (ISO 11426:2014), which has been technically
revised.The main changes compared to the previous edition are as follows:
— Extension of the scope to cover determination of gold in multiple types of alloys, not only in
jewellery ones;— Purity of proof samples was re-defined in 5;
— Specific procedures are described in 8 for samples with large amount of base metals, containing
platinum or palladium, or with a silver/gold ratio higher than 3;— Calculation were adapted to take into account the addition of fine gold and the fineness of the gold
used in the proof;— Repeatability requirements were changed;
— The use of scorification was removed.
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 2020 – All rights reserved
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oSIST prEN ISO 11426:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 11426:2020(E)
Jewellery and precious metals — Determination of gold —
Cupellation method (fire assay)
1 Scope
This document specifies a cupellation method (fire assay) for the determination of gold on a material
considered homogeneous. The gold content of the sample should preferably lie between 100 and
999,5 parts per thousand (‰). Finenesses above 999,5 ‰ can be determined using a spectroscopy
method by difference (e.g. ISO 15093).The procedure is applicable to most types of gold samples. Some modifications are indicated for specific
cases (presence of large amount of base metals, platinum or palladium, silver). It is not compatible with
the presence above trace levels of iridium, rhodium and ruthenium (more than 0.25 ‰ for the sum of
all three elements).This method is also intended to be used as the recommended method for the determination of fineness
in jewellery alloys covered by ISO 9202.2 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 15093, Jewellery and precious metals — Determination of high purity gold, platinum and palladium —
Difference method using ICP-OES3 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
cornet
alloy of gold and precious metals shaped in a roll, prior the parting process
3.2
gold cornet
gold shaped in a roll, after the parting process
3.3
parting
separation of silver and other metals from gold by digestion of those metals with nitric acid, in a
chloride-free environment3.4
proof sample
synthetic reference sample whose composition is as similar as possible to the sample; cupellation of the
proof sample is performed together with the sample, and its result is used to correct the final assay
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oSIST prEN ISO 11426:2020
ISO/DIS 11426:2020(E)
3.5
inquartation
addition of silver to gold alloys in a specific ratio in order to enable the parting of gold from silver by
means of nitric acid4 Principle
The gold alloys are inquarted with silver, compounded with lead and cupelled in a cupellation furnace
until a...
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