ISO INTERNATIONAL STANDARD 10136-3 First edition 1993-07-01 Glass and glassware Analysis of extract solutions : Part 3: Determination of calcium oxide and magnesium oxide by flame atomic absorption spectrometry Verre et verrerie -Analyse des solutions d'attaque spectrometrie d'absorption atomique dans la flamme Reference number ISO 10136-3:1993(E) ISO 10136-3:1993(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 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. 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. International Standard ISO 10136-3 was prepared by Technical Committee ISO/TC 48, Laboratory glassware and related apparatus, Sub-Committee SC 5, Quality of glassware. IsO 10136 consists of the following parts, under the general title Glass and glassware -Analysis of extract solutions: Part 1: Determination of silicon dioxide by molecular absorption spectrometry Part 2: Determination of sodium oxide and potassium oxide by flame spectrometric methods Part 3: Determination of calcium oxide and magnesium oxide by flame atomic absorption spectrometry Part 4: Determination of aluminium oxide by molecular absorption spectrometry Part 5: Determination of iron(lll) oxide by molecular absorption spectrometry and flameatomic absorption spectrometry Part 6: Determination of boron(ll) oxide by molecular absorption spectrometry Annex A of this part of ISO 10136 is for information only ISO1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfim, without per- mission in writing from the publisher. International Organizationfor Standardizatior Case Postale 56 . CH-1211 Geneve 20 · Switzerland Printed in Switzerland ii ISO 10136-3:1993(E) Introduction Classifications of glass or glassware, in National or International Standards and in the various pharmacopoeia, have relied for many years on a titration of extract solutions with a diluted mineral acid. Such solutions may contain not only the aikali metal oxides (sodium and potassium), but also the al- kaline earth oxides (calcium and magnesium), which are also titrated by acid. Thus, the determination is actually of the total alkalinity of the extract sodium oxide. In recent years, with the advent of more modern tech- niques, such as flame atomic absorption spectrometry, there has been a move towards a more compiete analysis of extract solutions and Technical Committee 2, Chemical Durability and Analysis, of the Inter- national Commission on Glass (ICG), investigated colorimetric methods for that none was particularly suitable for the determination of the very low utions. carbonates is necessary prior to the analytical determination. This is achieved by using spectroscopic buffer solutions, which are normally strongly acidic, or by addition of acids. ii