1、BS EN ISO 11426:2016Jewellery Determination ofgold in gold jewellery alloys Cupellation method (fire assay)(ISO 11426:2014)BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS EN ISO 11426:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementa
2、tion of EN ISO 11426:2016. It is identical to ISO 11426:2014. It supersedes BS EN ISO 11426:1999 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee STI/53, Specifications and test methods for jewellery andhorology.A list of organizations represented on thi
3、s committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 74799 1ICS 39.
4、060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 October 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORM
5、E EUROPENNE EUROPISCHE NORM EN ISO 11426 October 2016 ICS 39.060 Supersedes EN ISO 11426:1998English Version Jewellery - Determination of gold in gold jewellery alloys -Cupellation method (fire assay) (ISO 11426:2014) Joaillerie, bijouterie - Dosage de lor dans les alliages dor pour la bijouterie-jo
6、aillerie - Mthode de coupellation (essai au feu) (ISO 11426:2014) Schmuck - Bestimmung von Gold in Goldschmucklegierungen - Dokimastisches Verfahren (ISO 11426:2014) This European Standard was approved by CEN on 2 October 2017. CEN members are bound to comply with the CEN/CENELEC Internal Regulation
7、s 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. Th
8、is 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 mem
9、bers 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, Portu
10、gal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any fo
11、rm and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 11426:2016 EBS EN ISO 11426:2016EN ISO 11426:2016 (E) 3 European foreword The text of ISO 11426:2014 has been prepared by Technical Committee ISO/TC 174 “Jewellery” of the International Organization for Standardization
12、(ISO) and has been taken over as EN ISO 11426:2016. 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 April 2017, and conflicting national standards shall be withdrawn at the latest by April 2017. A
13、ttention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 11426:1998. According to the CEN-CENELEC Internal Regul
14、ations, 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, It
15、aly, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 11426:2014 has been approved by CEN as EN ISO 11426:2016 without any modification. BS EN ISO 11
16、426:2016ISO 11426:2014(E)Contents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Principle 14 Reagents 15 Apparatus . 26 Sampling 37 Procedure. 37.1 General . 37.2 Yellow and red gold alloys, free of nickel, and palladium white gold alloys 37.3 White gold alloys containing nickel
17、47.4 White gold alloys containing palladium 57.5 Gold alloys incorporating more than 40 % silver . 57.6 Alloys containing 999 gold. 58 Calculation and expression of results . 58.1 Proof assay sample factor 58.2 Calculation of gold content . 68.3 Repeatability . 69 Test report . 6Bibliography 7 ISO 2
18、014 All rights reserved iiiBS EN ISO 11426:2016ISO 11426:2014(E)ForewordISO (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 com
19、mittees. 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
20、 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 th
21、e 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. IS
22、O 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 docum
23、ent is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade
24、(TBT), see the following URL: Foreword Supplementary information .The committee responsible for this document is ISO/TC 174, Jewellery.This third edition cancels and replaces the second edition (ISO 11426:1997), which has been technically revised with the following changes: change in the scope that
25、this method is the referee method; change of requirement for sampling in Clause 6; addition of a warning in Clause 7 that suitable health and safety procedures should be followed; addition of red gold alloys in 7.2; addition of requirements in 7.3.1 for white gold alloys containing nickel and pallad
26、ium; standard editorially revised.iv ISO 2014 All rights reservedBS EN ISO 11426:2016ISO 11426:2014(E)IntroductionThe following definitions apply in understanding how to implement an ISO International Standard and other normative ISO deliverables (TS, PAS, IWA). “shall” indicates a requirement “shou
27、ld” indicates a recommendation “may” is used to indicate that something is permitted “can” is used to indicate that something is possible, for example, that an organization or individual is able to do somethingISO/IEC Directives, Part 2 (sixth edition, 2011), 3.3.1 defines a requirement as an “expre
28、ssion in the content of a document conveying criteria to be fulfilled if compliance with the document is to be claimed and from which no deviation is permitted.”ISO/IEC Directives, Part 2 (sixth edition, 2011), 3.3.2 defines a recommendation as an “expression in the content of a document conveying t
29、hat among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required, or that (in the negative form) a certain possibility or course of action is deprecated but not prohibited
30、.” ISO 2014 All rights reserved vBS EN ISO 11426:2016BS EN ISO 11426:2016Jewellery Determination of gold in gold jewellery alloys Cupellation method (fire assay)1 ScopeThis International Standard specifies a cupellation method (fire assay) for the determination of gold in gold jewellery alloys. The
31、gold content of the alloys should preferably lie between 333 and 999 parts per thousand ().The procedure is applicable specifically to gold alloys incorporating silver, copper, and zinc. Some modifications are indicated where nickel and/or palladium are present in the so-called white gold alloys, as
32、 well as for alloys containing 990 or more parts per thousand () of gold.This International Standard is intended to be used as the recommended method for the determination of fineness in alloys covered by ISO 9202.2 Normative referencesThe following documents, in whole or in part, are normatively re
33、ferenced 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.ISO 11596, Jewellery Sampling of precious metal alloys for and in jewell
34、ery and associated products3 PrincipleThe gold alloys are inquarted with silver, compounded with lead, and cupelled in a cupellation furnace until a precious metal button is obtained. After flattening and rolling, the silver is extracted (parted) in nitric acid and the gold weighed. Possible systema
35、tic errors in the procedure are eliminated by assaying standard proof samples in parallel.NOTE Inquartation is the addition of silver to gold alloys in a specific ratio in order to enable the parting of gold from silver by means of nitric acid.4 ReagentsDuring the analysis, unless otherwise stated,
36、use only reagents of recognized analytical grade and only distilled water or water of equivalent purity.4.1 Nitric acid (HNO3), 33 % (mass fraction), with sufficiently low content of halides (check with silver nitrate test).4.2 Nitric acid (HNO3), 49 % (mass fraction), with sufficiently low content
37、of halides (check with silver nitrate test).4.3 Lead, assay grade, free of precious metals and bismuth, as foil, beads, or tablets.4.4 Pure silver, for inquartation, minimum purity 999 parts per thousand () by mass, free of gold and platinum group metals.4.5 Pure gold, for proof samplesINTERNATIONAL
38、 STANDARD ISO 11426:2014(E) ISO 2014 All rights reserved 1BS EN ISO 11426:2016ISO 11426:2014(E) for determination of gold between 333 and 990 parts per thousand () by mass, minimum purity 999,99 parts per thousand () by mass, and for determination of gold more than 990 parts per thousand () by mass,
39、 minimum purity 999,99 parts per thousand () by mass.4.6 Pure palladium, for proof samples, minimum purity 999,5 parts per thousand () by mass, free of gold.4.7 Nickel, for proof samples, in a form of an appropriate pre-alloy (free of precious metals).4.8 Copper (foil or wire), for proof samples, mi
40、nimum purity 999 parts per thousand () by mass, free of gold and platinum group metals.4.9 Sodiumtetraborate (Na2B4O7), anhydrous.5 Apparatus5.1 Ordinary laboratory apparatus.5.2 Cupellation furnace, in which an oxidizing atmosphere can be maintained.CAUTION A standard muffle furnace is not satisfac
41、tory for this purpose.5.3 Magnesia cupels, in form of single or block cupels, capable of absorbing the resulting lead and base metal oxides.5.4 Parting flasks or nitric acid resistant basket, with thimbles.5.5 Annealing crucibles, made of refractory materials.5.6 Cupellation tongs.5.7 Assay pliers.5
42、.8 Polished anvil, which may be replaced by a press, polished and reserved for this purpose.5.9 Polished hammer, of minimum mass 400 g, which may be replaced by a press, polished, and reserved for this purpose.5.10 Scorification dishes, usually of 50 mm in diameter.5.11 Jewellers rolls.5.12 Scorific
43、ation tongs.5.13 Assay cleaning brush.5.14 Analytical balance, with a reading accuracy of 0,01 mg.2 ISO 2014 All rights reservedBS EN ISO 11426:2016ISO 11426:2014(E)6 SamplingThe sampling procedure for jewellery gold alloys shall be performed in accordance with ISO 11596.7 ProcedureWARNING Suitable
44、health and safety procedures should be followed.7.1 GeneralWhen the composition of the samples is unknown, a preliminary analysis by suitable means should be used to determine the approximate composition of the material, e.g. XRF analysis.7.2 Yellow and red gold alloys, free of nickel, and palladium
45、 white gold alloys7.2.1 Assay sampleTransfer at least two samples of the alloy, preferably between 125 mg and 250 mg, weighed to the nearest 0,01 mg, into assay-grade lead foil (4.3). The mass of the foil (or foil and beads) should be at least 4 g for considered gold alloy samples up to 200 mg, and
46、6 g for samples from 201 mg to 300 mg. Add pure silver (4.4) equivalent to 2,3 to 3 times the mass of fine gold present. Roll and compress the lead foil into a tight ball.7.2.2 Proof assay samplesWeigh, as in 7.2.1, at least two proof assay samples of pure gold (4.5) and pure silver (4.4) in masses
47、which correspond to the expected gold and silver contents (including the inquartation addition) of the assay sample. The total content of base metals in the assay samples is taken into consideration by the addition of a corresponding quantity of copper.Treat the proof assay samples and the assay sam
48、ples in 7.2.3 and 7.2.4 in the same manner.7.2.3 Cupellation and treatment of precious metal buttonsPlace the assay and the proof assay samples (7.2.2), tightly wrapped in lead foil, on magnesia cupels (5.3), which have been preheated to at least 1 000 C in the cupellation furnace (5.2).Place the cu
49、pels with the proof assay samples as close as possible to the corresponding assay samples in the cupellation furnace maintained at 1 050 C to 1 150 C. Continue heating (about 25 min) under oxidizing conditions until the cupellation process is completed. Remove the cupels from the furnace. Allow the precious metal buttons to cool down before lifting them from the cupels with the assay pliers (5.7). Squeeze the buttons and brush their undersides carefully with a brush (5.13) to remove any adhering cupel material. Flatten
