BS EN ISO 9289-1991 Oilseed residues - Determination of free residual hexane《油料饼粕 游离残留己烷测定》.pdf

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 ENISO9289:1995 has the status of a British StandardBSENISO9289:1995 This British Standard, having been prepared under the directionof the A

2、griculture andFood Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 29November1991 BSI 03-2000 The following BSI references relate to the work on this standard: Committee reference AFC/2 Draft for comment 89/50503 DC ISBN 0 580 20193 7 Commi

3、ttees responsible for this British Standard The preparation of this British Standard was entrusted by the Agriculture and Food Standards Policy Committee (AFC/-) to Technical Committee AFC/2, upon which the following bodies were represented: British Food Manufacturing Industries Research Association

4、 Department of Trade and Industry (Laboratory of the Government Chemist) FOSFA International Grain and Feed Trade Association Institute of Biology International Association of Seed Crushers Intervention Board for Agricultural Produce Ministry of Agriculture, Fisheries and Food National Farmers Union

5、 National Institute of Agricultural Botany Natural Resources Institute Royal Society of Chemistry Seed Crushers and Oil Processors Association Tropical Growers Association Amendments issued since publication Amd. No. Date Comments 8829 November 1995 Indicated by a sideline in the marginBSENISO9289:1

6、995 BSI 03-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN ISO 9289 3 Publication(s) referred to Inside back coverBSENISO9289:1995 ii BSI 03-2000 National foreword This Part of BS4325 has been prepared under the direction of the Agriculture a

7、nd Food Standards Policy Committee. It is identical with ISO9289:1991 “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 part. In 1995 the European Committee

8、 for Standardization (CEN) accepted ISO9289:1991 as European Standard ENISO9289:1995. As a consequence of implementing the European Standard this British Standard is renumbered as BSENISO9289 and any reference to BS4325-11 should be read as a reference to BSENISO 9289. A British Standard does not pu

9、rport 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 International Standard Corresponding British Standard

10、ISO 5500:1986 BS 6606:1987 Methods for sampling oilseed residues (Identical) ISO 5725:1986 BS 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 (Identical) Summary of pages This document co

11、mprises a front cover, an inside front cover, pages i and ii, theEN 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 the amendment table on the inside front cov

12、er.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 9289 August 1995 ICS 67.200.20 Descriptors: Agricultural products, oilseeds, chemical analysis, determination of content, hexane English version Oilseed residues Determination of free residual hexane (ISO9289:1991) Tourteaux de graines olag

13、ineuses Dosage de lhexane rsiduaire libre (ISO9289:1991) lsaatrckstande (Extraktionsschrote) Bestimmung des freien Resthexans (ISO9289:1991) This European Standard was approved by CEN on1995-05-24. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditio

14、ns for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three off

15、icial versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria,

16、 Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de

17、 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 its members Ref. No. ENISO 9289:1995 EENISO9289:1995 BSI 03-2000 2 Foreword The text of the International Standard from ISO/TC34, “Agricultural food produ

18、cts”, of the International Organization for Standardization (ISO) has been taken over as a European Standard by the Technical Committee CEN/TC307, “Oilseeds, vegetable and animal fats and oils and their by-products Methods of sampling and analysis”. This European Standard shall be given the status o

19、f a national standard, either by publication of an identical text or by endorsement, at the latest by February1996, and conflicting national standards shall be withdrawn at the latest by February1996. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement t

20、his European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative reference 3 3 Definition 3 4 Principle 3 5 Reagents an

21、d materials 3 6 Apparatus 3 7 Sampling and sample storage 4 8 Procedure 4 9 Expression of results 5 10 Precision 5 11 Test report 5 Table 1 Content of solvent (5.1) in the calibration samples 4 Table 2 Statistical results of the inter-laboratory test 6ENISO9289:1995 BSI 03-2000 3 1 Scope This Intern

22、ational 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 reference in this text, constitute provisions of this In

23、ternational 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 most recent edition of the standard indicated below.

24、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 proportion of volatile hydrocarbons, referred to genera

25、lly as hexane, remaining in oilseed residues after extraction with hydrocarbon-based solvents and which is desorbed directly by heating at80 C without the addition of water it is expressed as milligrams of n-hexane per kilogram of sample 4 Principle Desorption of hexane by heating at80 C in a closed

26、 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 otherwise stated. 5.1 Technical hexane or light petroleu

27、m, 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 than50% of n-hexane and consists predominantly ofC 6isomers. 5.2 Internal sta

28、ndard: use either5.2.1 or5.2.2. 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 Carrier gas, e.g.hydrogen, nitrogen, helium, etc., thoroughly dri

29、ed and containing less than10mg/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 sample to be analysed and having a low hexane content. If the hexan

30、e 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 of12% (m/m) to14% (m/m). In the case of samples having a different moisture content, it is necessary to car

31、ry 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 integrator and/or recorder, equipped with either a) a packed steel colum

32、n approximately2m long and of internal diameter approximately3,2mm, packed with an acid-washed diatomaceous earth support of particle size1504m to1804m (Chromosorb P NAW60/80 mesh 1)is suitable), and coated with10% squalane or methylpolysiloxane (SE30 1)is suitable), or b) a capillary column, approx

33、imately30m long and of0,3mm internal diameter, coated with methylpolysiloxane (SE30 1)is suitable) having a film thickness of0,24m. The injector and detector temperature shall be set at approximately120 C and the oven temperature at approximately40 C. The carrier gas pressure shall be set at approxi

34、mately0,3bar (30kPa). If a capillary column is used, the apparatus shall have a1/100 split injection system. NOTE 3For analyses in series, it is recommended to use a gas chromatograph having an automatic sample injection system, combined with a heating bath. 1) Chromosorb P NAW60/80, SE30, Perbunan

35、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 these products.ENISO9289:1995 4 BSI 03-2000 6.2 Heating bath, fitted with a rack to hold the f

36、lasks (6.4), capable of being set at80 C 2 C and of maintaining the set temperature constant to0,1 C. NOTE 4For continuous use, glycerol is recommended as the heating liquid. 6.3 Gas syringe, of 1ml capacity. 6.4 Septum flasks, of 20ml2% capacity. 6.5 Septa, inert to hexane, of approximately3mm thic

37、kness, made of a material such as nitrile rubber (e.g.Perbunan 1) ), or butyl rubber with a polytetrafluoroethylene or polychloroprene seam (e.g.Neoprene 1) ). Ensure that the septa used will produce a hermetic seal after crimping. NOTE 5The septa often have a very high mechanical resistance; if it

38、is thought, therefore, that the needle of the gas syringe may be damaged by using it to perforate 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

39、the septum flasks. 6.8 Liquid syringes, of 104l capacity. 7 Sampling and sample storage Sampling shall have been carried out in accordance with ISO5500. It is essential that loss of hexane from the sample be prevented. The laboratory sample shall fill a hermetically sealed container (preferably a cr

40、imped metal box) and shall be stored at4 C. Plastic containers shall not be used. The determination 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 nearest0,1g,5g of the calibration oilseed residues(5.5) into each of f

41、ive septum flasks(6.4). Seal each flask with a septum(6.5), cover with a foil cap(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 inTable 1 to four of the five flasks. Do not add solvent to the fifth flask. Table 1 Content of solvent (5.1)

42、in the calibration samples NOTE 6If samples with hexane contents greater than the highest value shown inTable 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 for24h. NOTE 7In the case of a shor

43、ter period, it is not certain that the technical hexane has been completely 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 s

44、yringe(6.8),54l of the internal standard(5.2.1 or5.2.2) to each of the five septum flasks through the septum. 8.1.5 At intervals of15min, place one septum flask after the other in the heating bath(6.2), set at80 C 2 C. The flasks shall be immersed in the heating liquid up to the level of the foil ca

45、p. 8.1.6 After heating each of the flasks for exactly60min, take, by means of the gas syringe(6.3) previously heated to between50 C and60 C, exactly1ml of the gaseous phase from the head-space, without removing the flasks from the heating bath. Quickly inject into the chromatograph the gaseous phase

46、 so removed. 8.1.7 From the chromatogram corresponding to the flask to which no technical hexane was added, calculate the hexane contentA c , 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 adde

47、d, calculate the calibration factor F using the formula where Flask 1 2 3 4 Volume of solvent added (4l) 1 2 4 7 Free hexane content (mg/kg) 134 268 536 938 A c is the hexane content calculated in8.1.7; A is is the content of the internal standard in the calibration oilseed concerned, expressed as a

48、 percentage of the total peak areas; A t is the total hydrocarbons content, including the internal standard, in the calibration oilseed residue concerned, expressed as a percentage of the total peak areas;ENISO9289:1995 BSI 03-2000 5 Calculate the mean calibration factorfrom the results of the four

49、calibration samples. shall be equal to1,0 0,1. 8.2 Determination 8.2.1 Weigh, to the nearest0,1g,5g of the laboratory sample into a septum flask(6.4). Seal the flask immediately with a septum(6.5), cover with a foil cap(6.6) and crimp using the pliers(6.7). These operations shall be performed rapidly. 8.2.2 inject54l of the internal standard(5.2.1 or5.2.2) into the septum flask through the septum using a syringe(6.8), and place the flask in the heating bath(6.2), set at80 C 2 C, for exactly60min. The flasks shall be im