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1、BRITISH STANDARD BS ISO 6656:2002 Animal and vegetable fats and oils Determination of polyethylene-type polymers ICS 67.200.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c)
2、 BSI BS ISO 6656:2002 This British Standard, having been prepared under the direction of the Consumer Products and Services Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 23 May 2002 BSI 23 May 2002 ISBN 0 580 39657 6 Nationa
3、l foreword This British Standard reproduces verbatim ISO 6656:2002 and implements it as the UK national standard. It supersedes BS 684-2.26:1986 (1995) which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/11, Animal and vegetable fats and oils, which ha
4、s the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the
5、 section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applica
6、tion. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; moni
7、tor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 6, an inside back cover and a back cover. The BSI copyright date displayed in this document
8、 indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARD ISO 6656 Second edition 2002-04-15 Reference number ISO 6656:2002(
9、E) Animal and vegetable fats and oils Determination of polyethylene-type polymers Corps gras dorigines animale et vgtale Dosage des polymres de type polythylne Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6656:2002(E) ii ISO 2002 Ar l
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15、:2002(E) iii 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
16、for which a technical committee has been established has the right to be represented on that 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) o
17、n all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Internation
18、al Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Int
19、ernational Standard ISO 6656 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils. This second edition cancels and replaces the first edition (ISO 6656:1984), which has been editorially revised to include warning notices about the use o
20、f certain solvents. Annex A of this International Standard is for information only. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6656:2002(E) iv Introduction The presence of polyethene-type polymers, which originate from packaging mat
21、erials, can cause serious difficulties in the processing of fats, as they can lead to deposits and blockages in pipes, valves, etc. In the manufacturer of soap, they may lead to the appearance of fibre marbling and undesirable specks. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 G
22、MT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARDISO 6656:2002(E) 1 Animal and vegetable fats and oils Determination of polyethylene-type polymers WARNING The method described in this International Standard requires the use of chloroform and tetrachloroethylene. These are toxic and oz
23、one-depleting substances. Avoid inhalation of and exposure to these solvents. Work in a fume cupboard when handling these solvents and solutions thereof. 1Scope This International Standard specifies the reference method for the determination of polyethylene-type polymers in animal and vegetable fats
24、 and oils. It has been established that below of polymers per kilogram the precision of the method is insufficient (see the results for tallow 1 in Table A.1). This method is used for animal fats and oils in particular. 2Term and definition For the purposes of this International Standard, the follow
25、ing term and definition applies. 2.1 polyethyene-type polymers impurities which are soluble in boiling tetrachloroethylene EXAMPLEPolyethylenes which originate from packaging materials. 3Principle After acid treatment to decompose any soaps present, a test portion is dissolved in chloroform (which l
26、eaves polyethylene-type polymers in suspension) and filtered through a sintered filter crucible containing a mat of filter aid. The crucible and its contents are washed, dried and weighed. Polyethylene-type polymers are extracted from the insoluble matter by boiling tetrachloroethylene. The crucible
27、 with its contents are dried and weighed again. 4Reagents Use only reagents of recognized analytical grade and distilled or deionized water or water of equivalent purity. 4.1Methanol, containing not more than (by mass) of water. 4.2Acetone. 4.3Chloroform. 4.4Tetrachloroethylene. 4.5Hydrochloric acid
28、, ethanolic solution. 50 mg 0,5 % Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6656:2002(E) 2 Mix 1 volume of hydrochloric avid () with 9 volumes of (by volume) ethanol. 4.6Diatomaceous earth-type filter aid, acid washed. 5Apparatus W
29、ARNING Apparatus made of plastic is likely to be affected by solvents (particularly chloroform or tetrachloroethylene). Care shall be taken to ensure that the solvents used do not come into contact with plastics. Usual laboratory equipment and, in particular, the following. 5.1Beakers, of capacity .
30、 5.2Filter flasks, of capacities and . 5.3Sintered filter crucibles, of porosity grade P 40 ( to ). 5.4Desiccator. 5.5Magnetic stirrer, with heater. 5.6Oven, capable of being maintained at . 5.7Analytical balance. 6Sampling Because the polymers are often heterogeneously distributed in a lot, particu
31、lar care is necessary to obtain representative samples. It is important the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling m
32、ethod is given in ISO 5555. 7Procedure WARNING Avoid contact of reagents with the skin. Do no inhale the vapours. Perform all operations under a suitable fume hood. 7.1Preparation of test sample Heat the sample of fat or oil to to . Stir the sample for to to ensure complete homogenization. 7.2Test p
33、ortion Weigh, to the nearest , about of the test sample (7.1) into a beaker (5.1). For samples expected to contain more than of polyethylene-type polymers per kilogram, the test portion may be reduced to . 20=1,19 g/ml95 % 1 000 ml 250 ml1 000 ml 16m40m 103 C 2 C 110 C 120 C 3 min4 min 0,1 g100 g1 0
34、00 ml 500 mg 50 g Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6656:2002(E) 3 7.3Acid treatment Add of the ethanolic hydrochloric acid (4.5) to the test portion, cover the beaker and stir on the magnetic stirrer (5.5) for at to . Cool
35、 to below , then add of chloroform (4.3) and stir until the fat or oil is dissolved (the solution may not be clear). Add of the filter aid (4.6) suspended in of chloroform (to avoid the formation of lumps). 7.4Determination 7.4.1Prepare a filter mat by suspending about of the filter aid (4.6) in of
36、chloroform and filtering through the sintered filter crucible (5.3). Using suction if necessary, filter the contents of the beaker (stirred immediately before filtration) into a filter flask (5.2). 7.4.2Rinse the beaker with about of chloroform and pour the rinsings slowly through the sintered filte
37、r crucible under suction, keeping the chloroform level in the crucible about above the filter mat. Repeat the rinsing with of methanol (4.1), taking the same precautions. 7.4.3Repeat the washing procedure, rinsing the crucible alternately with chloroform and methanol ( portions) until a total of of
38、chloroform and of methanol has been used. Continue suction until the crucible is dry. 7.4.4Wash the underside of the crucible with chloroform. Wash the contents of the crucible twice under suction with of acetone (4.2) in order to remove absorbed water. Suck air through the crucible for . 7.4.5When
39、the crucible appears to be dry, place it in the oven (5.6), set at , and leave for to . 7.4.6Allow the crucible to cool in the desiccator (5.4) for and weigh to the nearest . Repeat the drying, cooling and weighing procedures until the difference between two successive weighings does not exceed . Re
40、cord the mass (). 7.4.7Warm the crucible and its contents to in the oven (5.6), then wash the contents of the crucible with of boiling tetrachloroethylene (4.4), without suction if possible, using a clean dry filter flask (5.2) to collect the filtrate. Repeat the washing procedure four more times, u
41、sing portions of boiling tetrachloroethylene each time. Suck air through the crucible for . 7.4.8Wash the crucible with of acetone (4.2) to remove traces of tetrachloroethylene and suck air through the crucible for . 7.4.9Place the crucible in the oven (5.6), set at , and leave for to . Allow the cr
42、ucible to cool in the desiccator (5.4) for then weigh to the nearest . 7.4.10Repeat the washings with boiling tetrachloroethylene (see 7.4.7) and with acetone (see 7.4.8) and the drying, cooling and weighing procedures (see 7.4.9) until the difference between two successive weighings does not exceed
43、 . Record the mass (). 7.5Number of determinations Carry out two determinations on the same test sample. 8Expression of results The polyethylene-type polymer content, , expressed in milligrams per kilogram, is equal to 75 ml 5 min60 C 70 C 35 C 270 ml 1,0 g30 ml 0,5 g30 ml 1 000 ml 50 ml 5 mm 50 ml
44、50 ml 150 ml100 ml 25 ml1 min 103 C 15 min30 min 30 min0,1 mg 1 mgm1 103 C 25 ml250 ml 25 ml 2 min 50 ml 2 min 103 C 15 min30 min 30 min0,1 mg 1 mgm2 w w = m1 m2 m0 106 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6656:2002(E) 4 where
45、 is the mass, in grams, of the test portion (7.2); is the mass, in grams, of the crucible and insoluble matter before extraction (7.4.6); is the mass, in grams, of the crucible and insoluble matter after extraction (7.4.10). Take as the result the arithmetic mean of the values obtained in the two de
46、terminations. 9Precision Details of an interlaboratory test on the precision of the method are summarized in annex A. The values derived from this interlaboratory test may not be applicable to concentration ranges and matrices other than those given. 10Test report The test report shall specify: all
47、information necessary for the complete identification of the sample; the sampling method used, if known; the test method used, with reference to this International Standard; all operating details not specified in this International Standard, or regarded as optional, together with details of any inci
48、dents which may have influenced the test result(s); the test result(s) obtained or, if the repeatability has been checked, the final result obtained. m0 m1 m2 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:35:53 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6656:2002(E) 5 Annex A (inform
49、ative) Results of interlaboratory test An interlaboratory test, carried out at the international level, in which 10 laboratories participated, each carrying out a variable number of determinations, gave the statistical information (derived in accordance with ISO 5725:1986) summarized in Table A.1. Table A.1 Tallow 1Tallow 2 Number of laboratories retained after eliminating outliers109 Mean, 41184 Standard deviation of repeatability (), 815 Coefficient of variation of repeatability, 208,4 Repeatability limit ( ) (), 2324 Standard de
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