《BS-EN-ISO-9289-1995 BS-4325-11-1991.pdf》由会员分享，可在线阅读，更多相关《BS-EN-ISO-9289-1995 BS-4325-11-1991.pdf（12页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS EN ISO 9289:1995 BS 4325-11: 1991 Incorporating Amendment No. 1 Oilseed residues Determination of free residual hexane The European Standard EN ISO 9289:1995 has the status of a British Standard Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 13:56:46 GMT+00:00 2006, Uncon
2、trolled Copy, (c) BSI BS EN ISO 9289:1995 This British Standard, having been prepared under the direction of the Agriculture and Food Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 29 November 1991 BSI 03-2000 The following BSI reference
3、s relate to the work on this standard: Committee reference AFC/2 Draft for comment 89/50503 DC ISBN 0 580 20193 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Agriculture and Food Standards Policy Committee (AFC/-) to Technical Commit
4、tee AFC/2, upon which the following bodies were represented: British Food Manufacturing Industries Research Association Department of Trade and Industry (Laboratory of the Government Chemist) FOSFA International Grain and Feed Trade Association Institute of Biology International Association of Seed
5、Crushers Intervention Board for Agricultural Produce Ministry of Agriculture, Fisheries and Food National Farmers Union National Institute of Agricultural Botany Natural Resources Institute Royal Society of Chemistry Seed Crushers and Oil Processors Association Tropical Growers Association Amendment
6、s issued since publication Amd. No.DateComments 8829November 1995 Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 13:56:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 9289:1995 BSI 03-2000i Contents Page Committees responsibleInside front cover N
7、ational forewordii Foreword2 Text of EN ISO 92893 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 13:56:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 9289:1995 ii BSI 03-2000 National foreword This Part of BS 4325 has been prepared under t
8、he direction of the Agriculture and Food Standards Policy Committee. It is identical with ISO 9289:1991 “Oilseed residues Determination of free residual hexane”, published by the International Organization for Standardization (ISO), and in the preparation of which the United Kingdom played a full pa
9、rt. In 1995 the European Committee for Standardization (CEN) accepted ISO 9289:1991 as European Standard EN ISO 9289:1995. As a consequence of implementing the European Standard this British Standard is renumbered as BS EN ISO 9289 and any reference to BS 4325-11 should be read as a reference to BS
10、EN ISO 9289. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references Internation
11、al StandardCorresponding British Standard ISO 5500:1986BS 6606:1987 Methods for sampling oilseed residues (Identical) ISO 5725:1986BS 5497 Precision of test methods Part 1:1987 Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests (Iden
12、tical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN ISO title page, pages 2 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in th
13、e amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 13:56:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 9289 August 1995 ICS 67.200.20 Descriptors: Agricultural products, oilseeds, chemical analy
14、sis, determination of content, hexane English version Oilseed residues Determination of free residual hexane (ISO 9289:1991) Tourteaux de graines olagineuses Dosage de lhexane rsiduaire libre (ISO 9289:1991) lsaatrckstande (Extraktionsschrote) Bestimmung des freien Resthexans (ISO 9289:1991) This Eu
15、ropean Standard was approved by CEN on 1995-05-24. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references conc
16、erning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own
17、 language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland
18、 and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and i
19、ts members Ref. No. EN ISO 9289:1995 E Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 13:56:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 9289:1995 BSI 03-2000 2 Foreword The text of the International Standard from ISO/TC 34, “Agricultural food products”, of the International Organiza
20、tion for Standardization (ISO) has been taken over as a European Standard by the Technical Committee CEN/TC 307, “Oilseeds, vegetable and animal fats and oils and their by-products Methods of sampling and analysis”. This European Standard shall be given the status of a national standard, either by p
21、ublication of an identical text or by endorsement, at the latest by February 1996, and conflicting national standards shall be withdrawn at the latest by February 1996. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria,
22、Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword2 1Scope3 2Normative reference3 3Definition3 4Principle3 5Reagents and materials3 6Apparatus3 7Sampling and sam
23、ple storage4 8Procedure4 9Expression of results5 10Precision5 11Test report5 Table 1 Content of solvent (5.1) in the calibration samples4 Table 2 Statistical results of the inter-laboratory test6 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 13:56:46 GMT+00:00 2006, Uncontrolled Copy, (c) B
24、SI EN ISO 9289:1995 BSI 03-20003 1 Scope This International Standard specifies a method for the determination of the free residual hexane content in oilseed residues after extraction with hydrocarbon-based solvents. 2 Normative reference The following standard contains provisions which, through refe
25、rence in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the m
26、ost recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 5500:1986, Oilseed residues Sampling. 3 Definition For the purposes of this International Standard, the following definition applies. free residual hexane pro
27、portion of volatile hydrocarbons, referred to generally as hexane, remaining in oilseed residues after extraction with hydrocarbon-based solvents and which is desorbed directly by heating at 80 C without the addition of water it is expressed as milligrams of n-hexane per kilogram of sample 4 Princip
28、le Desorption of hexane by heating at 80 C in a closed vessel after addition of an internal standard. Determination of the hexane content in the head-space by gas chromatography using capillary or packed columns. 5 Reagents and materials All reagents shall be of recognized analytical grade unless ot
29、herwise stated. 5.1 Technical hexane or light petroleum, with a composition similar to that used in the industrial extraction of oilseeds or, failing these, n-hexane. NOTE 1It is recommended that technical hexane be used for the calibration. This reagent usually contains more than 50 % of n-hexane a
30、nd consists predominantly of C6 isomers. 5.2 Internal standard: use either 5.2.1 or 5.2.2. NOTE 2If the technical hexane used for the extraction or calibration contains appreciable amounts of cyclohexane, n-heptane should be used as the internal standard. 5.2.1 Cyclohexane 5.2.2 n-Heptane 5.3 Carrie
31、r gas, e.g. hydrogen, nitrogen, helium, etc., thoroughly dried and containing less than 10 mg/kg of oxygen. 5.4 Auxiliary gases 5.4.1 Hydrogen, 99,9 % pure, containing no organic impurities. 5.4.2 Air, containing no organic impurities. 5.5 Calibration oilseed residues, of the same origin as the samp
32、le to be analysed and having a low hexane content. If the hexane content is too high, reduce it by spreading the residue in a thin layer and leaving it to stand in the open air for several hours. Commercial oilseed residues usually have a moisture content of 12 % (m/m) to 14 % (m/m). In the case of
33、samples having a different moisture content, it is necessary to carry out the calibration with oilseed residues having the same moisture content as the sample. 6 Apparatus Usual laboratory apparatus and, in particular, the following. 6.1 Gas chromatograph, with flame ionization detector and an integ
34、rator and/or recorder, equipped with either a) a packed steel column approximately 2 m long and of internal diameter approximately 3,2 mm, packed with an acid-washed diatomaceous earth support of particle size 150 4m to 180 4m (Chromosorb P NAW 60/80 mesh1) is suitable), and coated with 10 % squalan
35、e or methylpolysiloxane (SE 301) is suitable), or b) a capillary column, approximately 30 m long and of 0,3 mm internal diameter, coated with methylpolysiloxane (SE 301) is suitable) having a film thickness of 0,2 4m. The injector and detector temperature shall be set at approximately 120 C and the
36、oven temperature at approximately 40 C. The carrier gas pressure shall be set at approximately 0,3 bar (30 kPa). If a capillary column is used, the apparatus shall have a 1/100 split injection system. NOTE 3For analyses in series, it is recommended to use a gas chromatograph having an automatic samp
37、le injection system, combined with a heating bath. 1) Chromosorb P NAW 60/80, SE 30, Perbunan and Neoprene are examples of suitable products available commercially. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of
38、these products. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 13:56:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 9289:1995 4 BSI 03-2000 6.2 Heating bath, fitted with a rack to hold the flasks (6.4), capable of being set at 80 C 2 C and of maintaining the set temperature constant to
39、 0,1 C. NOTE 4For continuous use, glycerol is recommended as the heating liquid. 6.3 Gas syringe, of 1 ml capacity. 6.4 Septum flasks, of 20 ml 2 % capacity. 6.5 Septa, inert to hexane, of approximately 3 mm thickness, made of a material such as nitrile rubber (e.g. Perbunan1), or butyl rubber with
40、a polytetrafluoroethylene or polychloroprene seam (e.g. Neoprene1). Ensure that the septa used will produce a hermetic seal after crimping. NOTE 5The septa often have a very high mechanical resistance; if it is thought, therefore, that the needle of the gas syringe may be damaged by using it to perf
41、orate septa, perforate them with a pin before taking the sample from the head-space. Reuse of septa is not recommended. 6.6 Metallic foil caps, for example made of aluminium. 6.7 Crimping pliers, for closing the septum flasks. 6.8 Liquid syringes, of 10 4l capacity. 7 Sampling and sample storage Sam
42、pling shall have been carried out in accordance with ISO 5500. It is essential that loss of hexane from the sample be prevented. The laboratory sample shall fill a hermetically sealed container (preferably a crimped metal box) and shall be stored at 4 C. Plastic containers shall not be used. The det
43、ermination of residual hexane shall be carried out as soon as the container has been opened. 8 Procedure 8.1 Calibration 8.1.1 Weigh, to the nearest 0,1 g, 5 g of the calibration oilseed residues (5.5) into each of five septum flasks (6.4). Seal each flask with a septum (6.5), cover with a foil cap
44、(6.6) and crimp using the pliers (6.7). 8.1.2 Add, using a syringe (6.8), the volume of solvent (5.1) specified in Table 1 to four of the five flasks. Do not add solvent to the fifth flask. Table 1 Content of solvent (5.1) in the calibration samples NOTE 6If samples with hexane contents greater than
45、 the highest value shown in Table 1 have to be tested, the volumes of solvent used for the calibration have to be increased accordingly. 8.1.3 Allow the flasks to stand at room temperature for 24 h. NOTE 7In the case of a shorter period, it is not certain that the technical hexane has been completel
46、y absorbed by the oilseed residue and, furthermore, that the sorption-desorption equilibrium of the technical hexane between the residue and the vapour phase has been reached. 8.1.4 At the end of this time add, by means of a syringe (6.8), 5 4l of the internal standard (5.2.1 or 5.2.2) to each of th
47、e five septum flasks through the septum. 8.1.5 At intervals of 15 min, place one septum flask after the other in the heating bath (6.2), set at 80 C 2 C. The flasks shall be immersed in the heating liquid up to the level of the foil cap. 8.1.6 After heating each of the flasks for exactly 60 min, tak
48、e, by means of the gas syringe (6.3) previously heated to between 50 C and 60 C, exactly 1 ml of the gaseous phase from the head-space, without removing the flasks from the heating bath. Quickly inject into the chromatograph the gaseous phase so removed. 8.1.7 From the chromatogram corresponding to
49、the flask to which no technical hexane was added, calculate the hexane content Ac, expressed as a percentage of the total peak areas. 8.1.8 From each of the chromatograms corresponding to each of the flasks to which technical hexane was added, calculate the calibration factor F using the formula where Flask1234 Volume of solvent added (4l) 1247 Free hexane content (mg/kg) 134268536938 Acis the hexane content calculated in 8.1.7; Aisis the content of the internal standard in the calibration oilseed concerned, expressed as a pe