ISO INTERNATIONAL STANDARD 17678 IDF 202 Second edition 2019-06 Milk and milk products Determination of milk fat purity by gas chromatographic analysis of triglycerides Lait etproduits laitiers-Determinationde la purete desmatieres des triglycerides Reference numbers IS017678:2019(E) ISO IDF202:2019(E) ISOandIDF2019 IS017678:2019(E) IDF 202:2019(E) COPYRIGHTPROTECTEDDOCUMENT @ ISO and IDF 2019 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 orIso's memberbody in the countryof therequester. ISO copyright office International Dairy Federation CP 401 : Ch. de Blandonnet 8 SilverBuilding·Bd Auguste Reyers70/B CH-1214 Vernier,Geneva B-1030 Brussels Phone:+41227490111 Phone:+3223256740 Fax:+41 22 749 09 47 Fax: +32 2 325 67 41 Email: copyright@iso.org Email: info@fil-idf.org Website: www.iso.org Website: www.fil-idf.org Published in Switzerland ii @ISO and IDF2019-All rights reserved IS0 17678:2019(E) IDF 202:2019(E) Contents Page Foreword ..iv 1 Scope ..1 2 Normative references 3 Terms and definitions 4 Principle 5 Reagents. 6 Apparatus. ..3 7 Sampling. ..4 8 Procedure .5 Preparation of test samples. .5 8.1 8.1.1 General .5 8.1.2 Isolationfrombutterorbutteroil .5 8.1.3 Extraction according to the Rose-Gottlieb gravimetric method .5 8.1.4 Extractionfrommilkusingsilicagelcolumns 5 8.1.5 Extractionfromcheese. .6 8.2 Preparationoffatsamplesolution .6 8.3 Chromatographictriglyceridedetermination 8.3.1 Baselinedrift .6 8.3.2 Injection technique 8.3.3 Calibration. .6 8.3.4 Chromatographic conditions. .7 9 Integration,evaluationandcontroloftheanalyticalperformance ..8 10 Calculationand expression ofresults .10 10.1 Triglyceride composition .10 10.1.1 Calculation ..10 10.1.2 Expression oftest results .10 10.2 S-values. .11 10.2.1 Calculation. .11 10.2.2 Expressionoftest results .11 10.3 Detection of foreign fat .11 11 Precision .12 11.1 Interlaboratorytest. ..12 11.2 Repeatability ..12 11.3 Reproducibility ..12 12 Test report. ..13 AnnexA (normative)Preparationofthepackedcolumn ..14 AnnexB (informative)Quantificationoftheforeignfatcontent ..18 AnnexC(informative)Uncertaintyofmeasurement ..20 AnnexD (informative)Interlaboratorytest. .21 Bibliography. .23 @IS0 and IDF 2019-All rights reserved iii