ISO INTERNATIONAL STANDARD 20595 First edition 2018-01-15 Water quality - Determination of selected highly volatile organic compounds in water Method using gas chromatography and mass spectrometry by static headspace technique (HS-GC-MS) Qualité de I'eau - Dosage de composés organiques hautement volatils selectionneés dans I'eau - Méthode par chromatographie en phase gazeuse par la technique de I'espace de tete statique et spectrométrie de masse (HS-GC-MS) Reference number IS0 20595:2018(E) ISO @ IS0 2018 IS0 20595:2018(E) COPYRIGHTPROTECTEDDOCUMENT IS0 2018, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. IsOcopyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii @ IS0 2018 - All rights reserved IS0 20595:2018(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. .1 2 Normative references 3 Terms and definitions ..3 4 Principle .3 5 Interferences ..4 5.1 General ..4 5.2 Interferences in the laboratory ..4 5.3 Interferencesbythematrix .4 5.4 Interferences in the headspace. ..4 5.5 Interferences during gas chromatography and mass spectrometry .4 6 Reagents .4 6.1 General .4 6.8 Examples of stock and standard solutions ..5 6.8.1 Stocksolution .5 6.8.3 Solution of the internal standards .5 6.8.4 Aqueous multi-component solution for the calibration ..5 7 Apparatus ..6 7.1 General. ..6 8 Sampling. .6 9 Procedure .7 9.1 Sample preparation .7 9.2 GC-MS operating conditions .7 9.3 Control measures .7 9.3.1 Blank value control. .7 9.3.2 Control over the total procedure .7 9.4 Identification of individual compounds .8 9.4.1 General .8 9.4.2 Identification of individual compounds with mass spectrometric detector .8 10 Calibration .10 10.1 General .10 10.2 Calibration with internal standard .11 11 Evaluation ..12 12 Expression of results .12 13 Test report ..12 Annex A (informative) Example of GC column, headspace vial and septum ..13 AnnexB (informative)Examples of internal standards ..14 Annex C (informative) Example of headspace and gas chromatographic conditions ..16 Annex D (informative) Performance data ..17 Bibliography ..24 @ IS0 2018 - All rights reserved iii