ISO 3656 AMD 1-2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction Amendment 1《动物和植物脂肪和油 特异性紫外.pdf

《ISO 3656 AMD 1-2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction Amendment 1《动物和植物脂肪和油 特异性紫外.pdf》由会员分享，可在线阅读，更多相关《ISO 3656 AMD 1-2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction Amendment 1《动物和植物脂肪和油 特异性紫外.pdf（8页珍藏版）》请在麦多课文档分享上搜索。

1、 ISO 2017 Animal and vegetable fats and oils Determination of ultraviolet absorbance expressed as specific UV extinction AMENDMENT 1 Corps gras dorigines animale et vgtale Dtermination de labsorbance dans lultraviolet, exprime sous la forme dextinction spcifique en lumire ultraviolette AMENDEMENT 1

2、INTERNATIONAL STANDARD ISO 3656 Fourth edition 2011-02-01 Reference number ISO 3656:2011/Amd.1:2017(E) AMENDMENT 1 2017-04 ISO 3656:2011/Amd.1:2017(E)ii ISO 2017 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no pa

3、rt 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 ISOs member b

4、ody in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 3656:2011/Amd.1:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwi

5、de 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 which a technical committee has been established has the right to be represented on tha

6、t committee. International organizations, governmental 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. The procedures used to develop this docu

7、ment and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directiv

8、es, Part 2 (see www .iso .org/ directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the develo

9、pment of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the voluntary na

10、ture of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: w w w . i s o .org/ iso/ foreword .html.

11、 This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils. ISO 2017 All rights reserved iii Animal and vegetable fats and oils Determination of ultraviolet absorbance expressed as specific UV extinction AMENDMENT 1 Page 1, Cla

12、use 1 Replace the text with the following: 1 Scope This document specifies a method for the determination of the absorbance at ultraviolet wavelengths of animal and vegetable fats and oils. Milk and milk products (or fat obtained from milk and milk products) are excluded from the scope of this docum

13、ent.Page 1, Clause 2 Replace the boilerplate text with the following: The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the lates

14、t edition of the referenced document (including any amendments) applies.Page 1, Clause 3 Add the following text above 3.1: ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online

15、 browsing platform: available at h t t p :/ www .iso .org/ obpPage 2, 6.3.3 Replace the text with the following: 6.3.3 Absorbance scale. This may be checked using a reference material consisting of four solutions of potassium dichromate in perchloric acid sealed in far UV quartz cells to measure the

16、 linearity and photometric accuracy reference in the UV. The potassium dichromate-filled cells (40 mg/l, 60 mg/l, 80 mg/l and 100 mg/l) are measured against a perchloric acid blank (see Reference 7). The net absorbance values are listed in the certificate of the reference material 1) . WARNING Potas

17、sium dichromate and potassium chromate are classified as CMR (carcinogenic, mutagenic, reprotoxic). Care shall be taken to avoid contact with the skin or exposure through inhalation. 1) Suitable holmium filters and potassium dichromate-sealed cells are available commercially, e.g. from Starna Scient

18、ific (www .starnascientific .com). This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of this supplier. ISO 3656:2011/Amd.1:2017(E) ISO 2017 All rights reserved 1 ISO 3656:2011/Amd.1:2017(E) NOTE 1 See Reference 8. In order to check

19、the linearity and accuracy of the absorbance scale, it is also possible to prepare a set of four solutions of potassium dichromate in 0,01 N sulfuric acid (for example: 40 mg/l, 60 mg/l, 80 mg/l and 100 mg/l). As an example, the following procedure has proved satisfactory. a) Dry a test portion of 1

20、 g of pure potassium dichromate for spectrophotometry at 100 C overnight. b) Weigh 0,100 g of dried potassium dichromate and dissolve in 0,01 N sulfuric acid solution in a 100 ml graduated flask and make up to the mark. c) Then, proceed to four different dilutions of this mixture with 0,01 N sulfuri

21、c acid solution: 5 ml - 50 ml, 4 ml - 50 ml, 3 ml - 50 ml and 2 ml - 50 ml. These solutions can be used for six months after their preparation. d) Measure the extinction of the four diluted solutions so obtained at 350 nm, 313 nm, 257 nm and 235 nm, using the 0,01 N sulfuric acid solution as a refer

22、ence. The objective is that the relation between the potassium dichromate concentration and the absorbance is linear (R 2higher than 0,99). The accuracy of the response can be verified with the 60 mg/l solution that needs to be prepared the day before the verification. e) Measure the extinction of t

23、he solution so obtained at 350 nm, 313 nm, 257 nm and 235 nm, using the 0,01 N sulfuric acid solution as a reference. The extinctions measured using a 1 cm cuvette will be as follows: (nm) Specific extinction Limits 235 124,5 122,9 to 126,2 257 144,0 142,4 to 145,7 313 48,6 47,0 to 50,3 350 106,6 10

24、4,9 to 108,2 NOTE 2 In order to check the accuracy of the response of the photocell and the photomultiplier, another possibility is to weigh 0,200 0 g of pure potassium chromate for spectrophotometry and dissolve in 0,05 N potassium hydroxide solution in a 1 000 ml graduated flask and make up to the

25、 mark. Take precisely 25 ml of the solution obtained, transfer to a 500 ml graduated flask and dilute up to the mark using the same potassium hydroxide solution. Measure the extinction of the solution so obtained at 275 nm, using the potassium hydroxide solution as a reference. The extinction measur

26、ed using a 1 cm cuvette will be 0,200 0,005.Page 5, Annex A Insert the following text above Table A.1: The test was performed on five samples: A: extra virgin olive oil; B: second centrifugation olive oil; C: refined olive-pomace oil; D: virgin olive oil + rapeseed oil + high oleic sunflower oil; E:

27、 olive oil + refined soybean oil.Page 8, Bibliography Add the following reference: 8 European Pharmacopoeia. 2.2.25. Absorption spectrophotometry, ultraviolet and visible. Seventh Edition. Council of Europe. 20082 ISO 2017 All rights reserved ISO 3656:2011/Amd.1:2017(E) ISO 2017 All rights reserved ICS 67.200.10 Price based on 2 pages