ISO INTERNATIONAL 20130 STANDARD First edition 2018-07 Soil quality Measurement of enzyme activity patterns in soil samples using colorimetric substrates in micro-well plates Qualitedusol-Mesurede I'activitéenzymatiquedansdes echantillons desolen utilisantdes substrats colorimetriques Referencenumber IS0 20130:2018(E) ISO @IS02018 IS020130:2018(E) COPYRIGHTPROTECTEDDOCUMENT IS02018 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address below or IsO's member body in the country of the requester: ISO copyright office CP 40i : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +4122.749 0111 Fax: +41 22 749 09 47 Email:[email protected] Website: www.iso.org Published in Switzerland ii IS02018-Allrights reserved IS020130:2018(E) Contents Page Foreword iv Introduction. V 1 Scope. .1 2 Normativereferences .1 3 Termsanddefinitions,symbolsandabbreviatedterms .1 3.1 Terms and definitions. 1 3.2 Symbols and abbreviated terms. 1 4 Principle 2 5 Reactives 2 25 5.1 Buffers and reageants 5.2 Substrates and standards Preparation of standard solutions 55 5.2.1 5.2.2 Preparationof substratesolutions. 6 Apparatus and materials 7 7 Procedure 8 7.1 Establishmentof calibrationcurves 8 7.1.1 General. 8 7.1.2 Solutionof PNP 8 7.1.3 Solution ofβ-naphthylamine. 8 7.1.4 Solutionofammoniumchloride 8 7.2 Sampling. 9 7.2.1 Samplepreparation. 9 7.2.2 Addition of substrate .10 7.2.3 Absorbancemeasurements 11 7.2.4 Measurementsofureaseactivities .12 8 Calculation of results .12 9 Expression of results .12 10 Validity criteria .12 ..13 11 Interlaboratoryvalidation 12 Test report. .13 Annex A (informative) Validation of the method and intralaboratory tests for evaluating soil enzymatic activities with colorimetric method .14 Annex B (informative) International ringtestforevaluating soil enzymatic activities with colorimetric method .19 Bibliography .28 @ IS0 2018 - All rights reserved iii