1、CEN EN*ISO*6892 95 3404569 0304575 OT = BRITISH STANDARD Oilseed residues - Determination of total residual hexane The European Standard EN IS0 8892 : 1995 has the status of a British Standard BS EN IS0 8892 : 1995 BS 4325 : Part 10 : 1995 BS EN IS0 8892 : 1995 This British Standard, having been pre
2、pared under the direction of the Consumer Products and Services Sector Board, was published under the authority of the Standards Board and comes into effect on 15 August 1995 O BSI 1995 The following BSI references relate to the work on this standard: Committee reference AW/2 Draft announced in BSZ
3、News February1994 ISBN O 580 24013 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Rchnical Committee AW/2, Oilseeds and residues, 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 Ministry of Agriculture, Fisheries and Food National Farmers Union National Institute of Agricultural Botany Royal Society of Chemistry Seed Crushers and
5、 Oil Processors Association Tropical Growers Association United Kingdom Agricultural Supply Trade Association Ltd. Amendments issued since publication Amd. No. I Date I lxt affected I I CEN EN*ISO*8892 95 3404589 0104577 97T BS EN IS0 8892 : 1995 Contents Page Committees responsible Inside front cov
6、er National foreword ii Foreword 2 Method 1 Scope and field of application 3 2 Reference 3 3 Principle 3 4 Reagents and materials 3 5 Apparatus 3 6 Sampling and sample storage 3 7 Procedure 4 8 Expression of results 4 9 Precision 4 10 %st report 4 able Statistical results of interlaboratory tests 5
7、i CEN EN*ISO*8892 95 = 3404589 0104578 806 E BS EN IS0 8892 : 1995 National foreword This British Standard has been prepared by kchnical Committee AWI2 and is the English language version of EN IS0 8892 : 1995 Oilseed residues - Detemzination of total residual hemm, published by the European Committ
8、ee for Standardization (CEN). It is identical with IS0 8892 : 1987 published by the International Organization for Standardization (ISO) and in the preparation of which the UK played a fuil part. It supersedes BS 4325 : lart 10 : 1988 which is withdrawn and from which it differs in that the cross-re
9、ferences have been updated. Cross-references Publication referred to Corresponding British Standard IS0 5500 : 1986 IS0 5725 : 1986 BS 6606 : 1987 Methods for sampling oilseed residues BS 5497 Precision of test methods Part 1 : 1987 Cuide for the determination of repeatability and reproducibility fo
10、r a standard test method by inter-laboratory tests Compliance with a British Standard does not of itself confer immunity from legal obligations. ii CEN EN*ISO*8892 95 = 3404589 0304579 742 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 8892 April 1995 ICs 67.200.20 Descriptors: agricultura
11、l products, oilseeds, chemical analysis, determination of content, hexane English version Oilseed residues - Determination of total residual hexane (IS0 8892 : 1987) burteaux de graines olagineuses - Dosage de lhexane rsiduaire total (IS08892 : 1987) lsaatrckstnde (Extraktionsschrot) - Bestimmung de
12、s gesamten Resthexans (IS0 8892 : 1987) This European Standard was approved by CEN on 1995-01-05. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-
13、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 translation under t
14、he 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, Luxembourg, Netherlands
15、, 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 O 1995 Copyright reserved to aIl CEN members Ref. No. EN IS0 8892 : 19
16、95 E CEN EN*ISO*8892 95 3404589 0104580 464 = Page 2 EN IS0 8892 : 1995 Foreword The text of the International Standard from ISO/TC 34, Agricultural food products, of the International Organization for Standardization (ISO) has been taken over as a European Standard by the Technical Committee CEN/TC
17、 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 publication of an identical text or by endorsement, at the latest by October 1995, and conflicting national
18、standards shaii be withdrawn at the latest by October 1995. According to the CENKENELEC 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,
19、Portugal, Spain, Sweden, Switzerland, United Kingdom. CEN EN*ISO*8892 95 3404589 0304583 3T0 m Page 3 EN IS0 8892 : 1995 Oilseed residues - Determination of total residual hexane 1 Scope and field of application This International Standard specifies a method for the deter- mination of the total amou
20、nt of volatile hydrocarbons, referred to generally as hexane, remaining in oilseed residues after extraction with hydrocarbon-based solvents. 2 Reference IS0 5500, Oilseed residues - Samding. 3 Principle Desorption of hexane by heating at 110 OC with water in a dosed vessel, and determination of the
21、 hexane in the headspace by gas chromatography using capillary or packed columns. Expression of the results as n-hexane. 4 Reagents and materials 4.1 Technical n-hexane 01 light petroleum, with a com position similar to that used in the industrial extraction of oilseeds, or failing that, n-hexane. 4
22、.2 containing less than 10 mg/kg of oxygen. Carnet gas : hydrogen or nitrogen, helium, etc., dry and 4.3 Auxiliary gases : - purities. Hydrogen, 99,9 % pure, containing no organic im- - Air, containing no organic impurities. 5 Apparatus Usual laboratory apparatus and in particular 5.1 Gas chromatogr
23、aph, with flame ionization detector and integrator and/or recorder, equipped with a glass capillary col- umn approrirnately 30 m long and 0.3 mm in diameter, coated with methylpolysiloxanes (film thickness 0.2 pm) or, failing this, a packed column at least 1,f m long and 2 to 4 mm inter- nal diamete
24、r, packed with acid-washed diatomaceous earth of particle size 150 to 180 pm2, and coated with methylpdysilox- anes 1. If a capillary column is used, the apparatus shall have a 1/100 input divider. 5.2 Electric oven, capable of being maintained at 110 OC. 5.3 with a valve. Gas syringe, graduated, of
25、 capacity 1 ml, preferably 5.4 the same volume to within 2 %. Penicillin-type flasks, of capacity 50 to 60 ml, all with. 5.5 Septa, inert to solvents, of approximatey 3mm thickness, of a material such as nitrile rubber (for example Perbunan), or butyl rubber with a PTFE or polychloroprene seam (for
26、example Neoprene). NOTE - Ensure that the septa used will produce a hermatic seal after crimping. 5.6 Metallic foil caps, for example of aluminium. 5.7 Crimping pliers. 5.8 Liquid syringe, of capacity 10 pl. 6 Sampling and sample storage See IS0 5500. It is essential that loss of hexane from the sam
27、 ple be prevented. The laboratory sample shall fill a completely stbled container (preferably a crimped metal box) and shall be stored at -20 OC or below (for example in a deepfreezer). Plastics containers shall not be used. The determination of residual hexane shall be carried out as soon as the co
28、ntainer has been brought to room temperature and opened. 1) SE 30 is suitable. 21 Chromasorb WAW is suitable. CEN EN*ISO*8892 95 3404589 0104582 237 = Page 4 EN IS0 8892 : 1995 7 Procedure 7.1 Test portion Weigh, to the nearest 0.1 g, 5 g of the laboratory sample into a flask (5.4). Add 2.5 ml of di
29、stilled 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 at 110 OC, for 90 min. When this time has elapsed, remove the fl
30、ask from the oven and leave to cd for 2 min, then agitate by inverting. NOTE - It 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 c hromstography NOTE - The septa often hew a very high mechanical resistance: if it b thoug
31、ht, 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 OC oven temperature : 4
32、0 OC Carrier gas pressure : 0.3 bar (30 kPa) 7.3.2 Test Using the gas syringe (5.3) previousiy heated to between 50 and 60 OC, take exactly 0.5 ml of the gaseous phase and inject quickly into the chromatograph. 7.3.3 Calibration Three points, for example with 2,5 and 10 pl of solvent, are usually su
33、fficient for constructing the calibration graph; they correspond to 284,660 and 1 320 mg/kg of hexane if the test portion is 5 g of residue. Prepare a calibration series using flasks (5.4) of the same capacity as those used for the determination. Add to the tlasks 6 ml of water”, fdlowed immediately
34、 by various quantities of n-hexane (4.11, measured accurately with the aid of the syringe (5.8). Seal each flask with a septum (5.51, cover with a foil cap (5.6) and crimp with the pliers (5.7). Place the various flasks for the establishment of one calibration graph in the oven for 15 min at 110 OC.
35、 At the end of this time, remove the flasks from the oven and leave to cool for 2 min. With the gas syringe heated to between 50 and 60 OC, take ex- actly 0.5mi of the headspace and inject quickly into the chromatograph. 7.4 Number of determinations Carry out two determinations on the same laborator
36、y sample. 8 Expression of results Construct the calibration graph by plotting the area of the sol- vent peak as a function of the mass of solvent introduced into the flask (1 pI corresponding to 660 pg). Determine the sum of the peak areas of the hexane and various hydrocarbons which usually make up
37、 the technical solvent (2-methyl pentane, 3-methyl pentane, methylcydopentane. cyclohexane, etc.). NOTE - Do not include peaks due to oxidation products if prasent in significant amounts, but report these separately. Read off from the calibration graph the mas, ml, in micrograms, of hexane present i
38、n the flask. The total iesidual hexane content of the residue, expressed in milligrams of hexane per kilogram, is equal to mt m0 where mo is the mass, in grams, of the test portion; ml is the mass, in microgram, of solvent present in th flask. Take as the result the arithmetic mean of the two determ
39、ina- tions. 9 Precision Two interiaboratory tests organized at the intemational Level with 12 laboratories participating, each carrying dut three determinations (No. 1). and 15 laboratories, each cariying out two determinations (No. 21, gave the statistical results (deter- mined in accordance with I
40、S0 5725) shown in the table. 10 Test report The test report shall show the method used and the results ob- tamed. It shall ais0 mention any operating details not spec*hd in this International Standard, or regarded as optional, together with details of any incidents likely to have influenced the resu
41、lts. The report shall include all the information necessary for the complete identification of the sample. II 5 g of hydrated residue per 2.5 ml of water occupies on average a dume of 6 ml. CEN EN*ISO*8892 95 3404589 0104583 I173 29 83 8.6 % Page 5 EN IS0 8892 : 1995 19 22 4,6 % 4.8 % 52 62 Table -
42、Statistical results of interlaboratory tests Results expressed in milligrams of hexane pet kilogram 109 32 % 306 Sample 83 125 21 % 28% 235 353 Interbboratory test Number of laboratories remaining after elimination of outliers Mean Repeetability standard deviation, s, Repeatability coefficient of va
43、riation Repeatability, 233 s, Reproducibility standard deviation, SR Reproducibility coefficient of variation Reproducibility, i,= SR Soya residue Colza (rape) residue I Sunflower 1 residue No. 2 No. 1 No. 1 No. 2 No. 1 I 341 lm I 450 I 452 97 1 35 7.8 % 100 109 24 % 308 39 4.0 % 111 2a9 30% 817 A s
44、tatistical anaiysiis 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 soya residue and 20 % for the colza (rape) resi
45、due. CEN EN*ISO*8892 95 = 3404589 0304584 OOT BS EN IS0 8892 : 1995 List of references See national foreword. CEN EN*ISO*8892 95 3404589 0304585 T4b = BS EN IS0 8892 : 1995 BS 4325 : part 10 : 1995 BSI 389 Chiswick High Road London W4 4AL BSI - British Standards Institution BSI is the independent na
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