ISO INTERNATIONAL STANDARD 6767 First edition 1990-09-01 Ambient air -- Determination of the mass concentration of sulfur dioxide Tetrachloromercurate (TCM)/pararosaniline method Air ambiant -- Determination de la concentration en masse du dioxyde desoufre-Methodeautetrachloromercurate(TcM)etala pararosaniline Reference number ISO 6767:1990(E) CopyrightInternationalOrganizationfor Standardization No reproduction or networking permited without license from IHS Not for Resale ISO 6767:1990(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (lsO 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, govern- mental and non-governmental, in liaison with IsO, also take part in the work. isO collaborates closely with the Internationat Electrotechnical Commission(lEC)onallmattersofelectrotechnicalstandardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Interna- tional Standard requires approval by at least 75 % of the member bodies castinga vote. International Standard Iso 6767 was prepared by Technical Committee IsO/TC146,Airquality Annexes A and B form an integral part of this International Standard. Annex C is for information only. ISO 1990 Ail rights reserved. No part of this pubilcation may be reproduced or utillzed In any form or by any means, electronic or mechanical, including photocopying and microfim, without permission in writing from the publisher. InternationalOrganizationforStandardization Case Postale 56· CH-1211 Geneve 20 · Switzerland PrlntedinSwitzerland Not for Resale ISO 6767:1990(E) Introduction This International s Standard is a g guideline, based on the West-Gaeke method, for the determination of the mass concentration of sulfur diox- ide in ambient air. In annex A, a test is given for the purity and purifi- cation of pararosaniline hydrochloride; in annex B, a determination is given for the mass concentration of sulfur dioxide present in the sodium disuifite solution used for routine checks; in annex C, a method is given for the recovery of mercury from fresh and used solutions. i No reproduction or networking permited withoutlicene from IHs by IHS under license with IS( Not for Resale