1、BRITISH STANDARD BS EN ISO 8892:1995 BS 4325-10: 1995 Oilseed residues Determination of total residual hexane The European Standard EN ISO 8892:1995 has the status of a British StandardBSEN ISO 8892:1995 This British Standard, having been prepared under the directionof the Consumer Products and Serv
2、ices Sector Board, was published under theauthority of the Standards Board and comes into effect on 15August1995 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference AW/2 Draft announced in BSI News February 1994 ISBN 0 580 24013 4 Committees responsible
3、for this British Standard The preparation of this British Standard was entrusted to Technical Committee AW/2, Oilseeds and residues, upon which the following bodies were represented: British Food Manufacturing Industries Research Association Department of Trade and Industry (Laboratory of the Govern
4、ment Chemist) FOSFA International Grain and Feed Trade Association Institute of Biology Ministry of Agriculture, Fisheries and Food National Farmers Union National Institute of Agricultural Botany Royal Society of Chemistry Seed Crushers and Oil Processors Association Tropical Growers Association Un
5、ited Kingdom Agricultural Supply Trade Association Ltd. Amendments issued since publication Amd. No. Date CommentsBSEN ISO 8892:1995 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 1 Scope and field of application 3 2 Reference 3 3 Principle 3 4
6、Reagents and materials 3 5 Apparatus 3 6 Sampling and sample storage 3 7 Procedure 3 8 Expression of results 4 9 Precision 4 10 Test report 4 Table Statistical results of interlaboratory tests 5 List of references Inside back coverBSEN ISO 8892:1995 ii BSI 10-1999 National foreword This British Stan
7、dard has been prepared by Technical Committee AW/2 and is the English language version of EN ISO8892:1995 Oilseed residues Determination of total residual hexane, published by the European Committee for Standardization (CEN). It is identical with ISO8892:1987 published by the International Organizat
8、ion for Standardization (ISO) and in the preparation of which the UK played a full part. It supersedes BS4325-10:1988 which is withdrawn and from which it differs in that the cross-references have been updated. A British Standard does not purport to include all the necessary provisions of a contract
9、. 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 Publication referred to Corresponding British Standard ISO 5500:1986 BS 6606:1987 Methods for sampling oilseed re
10、sidues 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 Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN ISO title page,
11、pages2to6, 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 cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 8892 April 1995 ICS 67.200.
12、20 Descriptors: Agricultural products, oilseeds, chemical analysis, determination of content, hexane English version Oilseed residues Determination of total residual hexane (ISO 8892:1987) Tourteaux de graines olagineuses Dosage de lhexane rsiduaire total (ISO 8892:1987) lsaatrckstnde (Extraktionssc
13、hrot) Bestimmung des gesamten Resthexans (ISO 8892:1987) This European Standard was approved by CEN on 1995-01-05. 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
14、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 official versions (English, French, German). A version in any other language made by t
15、ranslation 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, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxem
16、bourg, 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 Stassart 36, B-1050 Brussels 1995 Copyright reserved to all CEN members Ref. No. E
17、N ISO 8892:1995 EEN ISO 8892:1995 BSI 10-1999 2 Foreword The text of the International Standard from ISO/TC34, Agricultural food products, of the International Organization for Standardization (ISO) has been taken over as a European Standard by the Technical Committee CEN/TC307, Oilseeds, vegetable
18、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 publication of an identical text or by endorsement, at the latest by October1995, and conflicting national standards shall be withdrawn
19、at the latest by October1995. According to the CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Swit
20、zerland, United Kingdom.EN ISO 8892:1995 BSI 10-1999 3 1 Scope and field of application This International Standard specifies a method for the determination of the total amount of volatile hydrocarbons, referred to generally as hexane, remaining in oilseed residues after extraction with hydrocarbon-
21、based solvents. 2 Reference ISO 5500, Oilseed residues Sampling. 3 Principle Desorption of hexane by heating at110 C with water in a closed vessel, and determination of the hexane in the headspace by gas chromatography using capillary or packed columns. Expression of the results as n-hexane. 4 Reage
22、nts and materials 4.1 Technical n-hexane or light petroleum, with a composition similar to that used in the industrial extraction of oilseeds, or failing that, n-hexane. 4.2 Carrier gas: hydrogen or nitrogen, helium, etc., dry and containing less than 10mg/kg of oxygen. 4.3 Auxiliary gases Hydrogen,
23、 99,9% pure, containing no organic impurities. Air, containing no organic impurities. 5 Apparatus Usual laboratory apparatus and in particular 5.1 Gas chromatograph, with flame ionization detector and integrator and/or recorder, equipped with a glass capillary column approximately30m long and0,3mm i
24、n diameter, coated with methylpolysiloxanes 1)(film thickness 0,24m) or, failing this, a packed column at least 1,7m long and2 to4mm internal diameter, packed with acid-washed diatomaceous earth of particle size 150 to1804m 2) , and coated with methylpolysiloxanes 1) . If a capillary column is used,
25、 the apparatus shall have a1/100 input divider. 5.2 Electric oven, capable of being maintained at110 C. 5.3 Gas syringe, graduated, of capacity 1ml, preferably with a valve. 5.4 Penicillin-type flasks, of capacity50 to 60ml, all with the same volume to within 2%. 5.5 Septa, inert to solvents, of app
26、roximately 3mm thickness, of a material such as nitrile rubber (for example Perbunan), or butyl rubber with a PTFE or polychloroprene seam (for example Neoprene). NOTEEnsure that the septa used will produce a hermetic seal after crimping. 5.6 Metallic foil caps, for example of aluminium. 5.7 Crimpin
27、g pliers 5.8 Liquid syringe, of capacity 10 4l. 6 Sampling and sample storage See ISO 5500. It is essential that loss of hexane from the sample be prevented. The laboratory sample shall fill a completely sealed container (preferably a crimped metal box) and shall be stored at 20 C or below (for exam
28、ple in a deep-freezer). Plastics containers shall not be used. The determination of residual hexane shall be carried out as soon as the container has been brought to room temperature and opened. 7 Procedure 7.1 Test portion Weigh, to the nearest 0,1g, 5g of the laboratory sample into a flask (5.4).
29、Add 2,5ml of distilled water, seal the flask with a septum (5.5), cover with a foil cap (5.6) and crimp with the pliers (5.7). All these operations shall be performed rapidly. 7.2 Desorption of the hexane Place the flask in the oven (5.2), maintained at110 C, for 90min. When this time has elapsed, r
30、emove the flask from the oven and leave to cool for2min, then agitate by inverting. NOTEIt is important to leave the flasks in the oven for the same length of time for each sample. 7.3 Analysis of the headspace by gas chromatography NOTEThe septa often have a very high mechanical resistance; if it i
31、s thought, therefore, that the needle of the gas syringe may be damaged by using it to perforate septa, perforate instead with a pin before taking the sample from the headspace. Reuse of septa is not recommended. 7.3.1 Setting of the apparatus Injector and detector temperature: 120 C Oven temperatur
32、e: 40 C Carrier gas pressure: 0,3 bar (30 kPa) 1) SE 30 is suitable. 2) Chromosorb WAW is suitable.EN ISO 8892:1995 4 BSI 10-1999 7.3.2 Test Using the gas syringe (5.3) previously heated to between50 and60 C, take exactly 0,5ml of the gaseous phase and inject quickly into the chromatograph. 7.3.3 Ca
33、libration Three points, for example with 2, 5 and 104l of solvent, are usually sufficient for constructing the calibration graph; they correspond to264,660 and1320 mg/kg of hexane if the test portion is5g of residue. Prepare a calibration series using flasks (5.4) of the same capacity as those used
34、for the determination. Add to the flasks6ml of water 3) , followed immediately by various quantities of n-hexane (4.1), measured accurately with the aid of the syringe(5.8). Seal each flask with a septum (5.5), cover with a foil cap (5.6) and crimp with the pliers(5.7). Place the various flasks for
35、the establishment of one calibration graph in the oven for15min at110 C. At the end of this time, remove the flasks from the oven and leave to cool for2min. With the gas syringe heated to between50 and 60 C, take exactly 0,5ml of the headspace and inject quickly into the chromatograph. 7.4 Number of
36、 determinations Carry out two determinations on the same laboratory sample. 8 Expression of results Construct the calibration graph by plotting the area of the solvent peak as a function of the mass of solvent introduced into the flask (14l corresponding to 6604g). Determine the sum of the peak area
37、s of the hexane and various hydrocarbons which usually make up the technical solvent (2-methyl pentane, 3-methyl pentane, methylcyclopentane, cyclohexane, etc.). NOTEDo not include peaks due to oxidation products if present in significant amounts, but report these separately. Read off from the calib
38、ration graph the mass, m 1 , in micrograms, of hexane present in the flask. The total residual hexane content of the residue, expressed in milligrams of hexane per kilogram, is equal to where m 0is the mass, in grams, of the test portion; m 1is the mass, in micrograms, of solvent present in the flas
39、k. Take as the result the arithmetic mean of the two determinations. 9 Precision Two interlaboratory tests organized at the international level with12 laboratories participating, each carrying out three determinations (No.1), and15 laboratories, each carrying out two determinations (No.2), gave the
40、statistical results (determined in accordance with ISO5725) shown in the Table. 10 Test report The test report shall show the method used and the results obtained. It shall also mention any operating details not specified in this International Standard, or regarded as optional, together with details
41、 of any incidents likely to have influenced the results. The report shall include all the information necessary for the complete identification of the sample. 3) 5 g of hydrated residue per 2,5 ml of water occupies on average a volume of 6ml. m 1 m 0 -EN ISO 8892:1995 BSI 10-1999 5 Table Statistical
42、 results of interlaboratory tests Results expressed in milligrams of hexane per kilogram Sample Soya residue Sunflower residue Colza (rape) residue Interlaboratory test No. 2 No. 1 No. 1 No. 2 No. 1 Number of laboratories remaining after elimination of outliers 15 11 11 15 10 Mean 341 400 450 452 97
43、1 Repeatability standard deviation, s r 29 19 22 35 39 Repeatability coefficient of variation 8,6 % 4,6 % 4,8 % 7,8 % 4,0 % Repeatability, 2,83 s r 83 52 62 100 111 Reproducibility standard deviation, s R 108 83 125 109 289 Reproducibility coefficient of variation 32 % a 21 % 28 % 24 % a 30 % Reprod
44、ucibility, 2,83 S R 305 235 353 308 817 a A statistical analysis of the results of the interlaboratory test No. 2, only taking into account the nine laboratories having participated in both the interlaboratory tests No. 1 and No. 2, gave a reproducibility coefficient of variation of 18 % for the soy
45、a residue and 20 % for the colza (rape) residue.6 blankBSEN ISO 8892:1995 BSI 10-1999 List of references See national foreword.BS EN ISO 8892:1995 BS 4325-10: 1995 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing B
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