ISO INTERNATIONAL STANDARD 10136-1 First edition 1993-07-01 Glass and glassware - Analysis of extract solutions Part 1: Determination of silicon dioxide by molecular absorption spectrometry Verre et verrerie - Analyse des solutions d'attaque - Partie 1: Dosage du dioxyde de silicium par spectrométrie d'absorption moléculaire Reference number ISO 10136-1:1993(E) IS0 10136-1:1993(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 represented on that committee. International organizations, governmental and non-governmental, in liaison with isO, also take part in the work. IsO collaboratescloselywiththeInternationalElectrotechnicalCommission (lEC)onall matters of electrotechnicalstandardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International a vote. International Standard ISO 10136-1 was prepared by Technical Committee ISO/TC48,Laboratoryglasswareandrelatedapparatus,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: --Part1: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 flame atomic absorption spectrometry Part 6: Determination of boron(lll) 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 microfilm,without per- mission in writing from the publisher. International OrganizationforStandardization CasePostale56·CH-1211Geneve20·Switzertand Printed in Switzerland ii ISO10136-1:1993(E) Introduction The determination of silica (SiO2) in durability extract solutions has not, hitherto, been included in classifications of glass or glassware according to chemical resistance. Indeed, in many applications the concentrations ofsilicafoundinsuchextractsolutions,normallyverylow,arenotsigniti- cant and are of little interest. There are occasions where such releases of small concentrations of silica in solutions or, in some cases, releases from medical and pharmaceutical ware. Then again, in examining the properties of new glass compositions it could be an advantage to know the fuil analysis of the durability extract solutions. Technical Committee 2, Chemical Durability and Analysis, of the Inter- national Commission on Glass (iCG), investigated two procedures for de- spectrometric technique. Both were based on the formation of colour complexes in the presence of ammonium molybdate, one using the yellow colour of the complex formed, the other using the blue colour produced when a suitable reducing agent is added. In collaborative experimental work, twelve laboratories analysed silica in two synthetic solutions and in extract solutions produced by the test described in ISO 4802[314]. It was agreed that whilst determinations using the yellow complex were more consistent, they were also less sensitive and, since the concentrations of silica in extract solutions are normally very low, the blue complex method waspreterred The results of investigations on turbidities, especially in grain test sol- utions, showed that acidification to dissolve possible hydroxides and/or carbonates is necessary prior to the analytical determina