ISO INTERNATIONAL 12740 STANDARD First edition 1998-12-01 Lead sulfide concentrates Determination of silver and gold contents Fire assay and flame atomic absorption spectrometric method using scorification or cupellation Concentres sulfures de plomb - Dosage de I'argent et de I'or - Methode par voie seche et spectrometrie d'absorption atomique dans la flamme a partir d'une scorification ou d'une coupellation ISO Reference number ISO 12740:1998(E) ISO 12740:1998(E) Contents Page 1 Scope 2 Normative references 3 Principle .. 4Reagents 5 Apparatus 6 Sample .. .5 7Procedure 8 Expression of results 10 9 Precision. .10 10 Test report . Annex A (normative) Procedure for the preparation and determination of the mass of a predried testportion Annex B (normative) Trial fusion.. .16 Annex C (normative) Blank determination 17 Annex D (normative) Flowsheet of the procedure for the acceptance of analytical values for the test samples.. 18 Annex E (informative) Derivation of precision equations .... .19 Annex F (informative) Bibliography 26 @ISO1998 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. InternationalOrganizationforStandardization Casepostale56·CH-1211Geneve20·Switzerland Internet [email protected] Printed in Switzerland @ISO ISO 12740:1998(E) Foreword ISsO (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 liaison with ISO, also take part in the work. IsO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Annexes A to D form an integral part of this International Standard, annexes E and F are for information only.