ISO INTERNATIONAL STANDARD 10359-1 First edition 1992-12-01 Water quality - Determination of fluoride Part 1: Electrochemical probe method for potable and lightly polluted water Qualité de I'eau - Dosage des fluorures Partie 1: Méthode de la sonde électrochimique pour I'eau potable et faiblementpolluée Reference number ISO 10359-1:1992(E) IS0 10359-1:1992(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 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 10359-1 was prepared by Technical Committee ISO/TC 147. Water quality, Sub-Committee SC 2, Physical, chemical, biochemical methods. quality - Determination of fluoride: Part 1: Electrochemical probe method for potable and lightly polluted water Part 2: Determination of inorganically bound total fluoride after di- gestion and distillation Annex A of this part of ISO 10359 is for information only. ISO1992 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 Organization for Standardization Case Postale 56 · CH-1211 Geneve 20 · Switzerland Printed in Switzerland ii ISO 10359-1:1992(E) Introduction Fluoride ions occur in almost all ground and surface waters. Their con- generally below 1 mg/l. Certain industrial waste waters may also contain fluoride ions in higher concentrations. The fluoride value is also dependant on the type and,concentration of cations present at the same time in water, such as Ca?+,. Mg?+, Aj3+ or Fe'+, which may form sparingly soluble compounds with fluoride ions or complexes of low dissociation constant. Apart from these compounds, stable boron-fluoride complexes exist. Several different methods are available for determining fluoride and the choice of method depends on the type of problem posed as follows a) Direct measurement using fluoride ion selective electrodes. This method is suitable for the determination of fluoride in potable and surface water. It is specified in this part of ISO 10359. position, distillation and potentiometric measurement. This method will be specified in ISO 10359-2. ili