1、BRITISH STANDARD BS 5766-18: 1999 ISO 6492:1999 Methods for analysis of animal feeding stuffs Part 18: Determination of fat content ICS 65.120BS5766-18:1999 This British Standard, having been prepared under the directionof the Consumer Products and Services Sector Committee, was published underthe a
2、uthority of the Standards Committee and comesinto effect on 15October1999 BSI 04-2000 ISBN 0 580 32996 8 National foreword This British Standard reproduces verbatim ISO 6492:1999 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committ
3、ee AW/10, Animal feeding stuffs, which has the responsibility to: 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; monitor related international and Euro
4、pean developments and promulgate them in the UK. 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 Stand
5、ards Catalogue under the 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 f
6、or their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theISO title page, pages ii to iv, pages 1 to 6, an inside back cover andabackcov
7、er. 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. Amendments issued since publication Amd. No. Date CommentsBS5766-18:1999 BSI 04-2000 i Contents Page National foreword Inside fro
8、nt cover Foreword iii Text of ISO 6492 1ii blankBS5766-18:1999 ii BSI 04-2000 Contents Page Foreword iii 1 Scope 1 2 Normative references 1 3 Term and definition 1 4 Principle 1 5 Reagents and materials 1 6 Apparatus 2 7 Sampling 2 8 Preparation of test sample 2 9 Procedure 2 10 Calculation 3 11 Pre
9、cision 4 12 Test report 4 Annex A (informative) Results of interlaboratory tests 5 Bibliography Inside back cover Table 1 Repeatability limit (r) and reproducibility limit (R) 4 Table A.1 Statistical results of interlaboratory tests on samples of category B 5 Table A.2 Statistical results of interla
10、boratory tests of the method with samples of category A 6BS5766-18:1999 BSI 04-2000 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
11、through ISO technical committees. Each member body interested in a subject 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 coll
12、aborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part3. Draft International Standards adopted by the technical committees are
13、 circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO 6492 was prepared by Technical Committee ISO/TC 34, Agricultural food products, Subcommittee SC10, Animal feeding stu
14、ffs. Annex A of this International Standard is for information only.iv blankBS5766-18:1999 BSI 04-2000 1 1 Scope This International Standard specifies a method for the determination of the fat content of animal feeding stuffs. The method is applicable to animal feeding stuffs except oilseeds and oil
15、seed residues. For the purposes of this method, the following two categories of animal feeding stuffs are distinguished. Samples of products in category B need a hydrolysis step prior to extraction. Category B: straight feeds of animal origin including milk products; straight feeds of vegetable orig
16、in from which fats cannot be extracted without prior hydrolysis; in particular: gluten, yeast, soya and potato proteins, and heat-treated feeds; compound feeds containing the preceding products in such quantities that at least20% of the fat content stems from these products. Category A: animal feedi
17、ng stuffs not mentioned under category B. NOTEFor oilseed residues, a method for the determination ofthe “oil content” by hexane extraction is specified in ISO734-12, whereas a method for the determination of the “oilcontent” by diethyl ether extraction is specified in ISO7363. For oilseeds, a metho
18、d for the determination of the “oil content” by hexane extraction is specified in ISO6591. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendme
19、nts to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest editi
20、on of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 3696, Water for analytical laboratory use Specification and test methods. ISO 6498, Animal feeding stuffs Preparation of test samples. 3 Term and definition For
21、 the purposes of this International Standard, the following term and definition apply. 3.1 fat content mass fraction of substances extracted from the sample by the procedure specified in this International Standard NOTEThe fat content is expressed in grams per kilogram. It may also be expressed as a
22、 mass fraction in percent. 4 Principle 4.1 Samples with a relative high fat content (atleast200g/kg) undergo a preliminary extraction with light petroleum. 4.2 For samples of category B, the sample is hydrolysed with hydrochloric acid under heating. The solution is cooled and filtered. The residue i
23、s washed and dried then extracted with light petroleum. The solvent is removed by distillation and drying. The residue is weighed. 4.3 For samples of category A, the sample is extracted with light petroleum. The solvent is removed by distillation and drying. The residue is weighed. 5 Reagents and ma
24、terials Use only reagents of recognized analytical grade. 5.1 Water, complying with at least grade 3 in accordance with ISO 3696. 5.2 Sodium sulfate, anhydrous. 5.3 Light petroleum, consisting mainly of hydrocarbons with six carbon atoms, boiling range40 C to 60 C. The bromine value shall be less th
25、an 1. The evaporation residue shall be less than 20mg/l. Alternatively, technical hexane may be used having an evaporation residue of less than 20mg/l. 5.4 Silicon carbide chips or glass beads. 5.5 Acetone 5.6 Hydrochloric acid, c(HCl) = 3 mol/l. 5.7 Filtration aid, for example diatomaceous earth (K
26、ieselguhr), boiled for30min in hydrochloric acid, c(HCl)=6mol/l, washed with water until acid-free, then dried at 130 C.BS5766-18:1999 2 BSI 04-2000 6 Apparatus Usual laboratory apparatus and, in particular, the following. 6.1 Extraction thimbles, free from fats and oils, ether-washed. 6.2 Soxhlet-t
27、ype extractor, with syphoning volume of about 100ml, or other recirculation extractor. 6.3 Heating apparatus, with temperature control, not liable to act as an ignition source. 6.4 Drying oven, capable of being maintained at(103 2) C. 6.5 Electrically heated vacuum oven, capable of being maintained
28、at (80 2) C and of reducing the pressure to less than 13,3kPa, fitted with a device for the introduction of dry air or containing a desiccant, for example calcium oxide. 6.6 Desiccator, containing an efficient desiccant. 7 Sampling Sampling is not part of the method specified in this International S
29、tandard. A recommended sampling method is given in ISO64974. It is important that the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage. Store the sample in such a way that deterioration and change in composition are minimized.
30、8 Preparation of test sample Prepare the test sample in accordance with ISO6498. 9 Procedure 9.1 Procedure selection If the test sample is difficult to crush, or if it is difficult to obtain a homogeneous reduced test sample because of a high fat content (exceeding200g/kg), proceed in accordance wit
31、h9.2. In all other cases proceed in accordance with 9.3. 9.2 Preliminary extraction 9.2.1 Weigh (m 0 ) at least20g of the prepared test sample (clause 8) to the nearest1mg and mix with10g of anhydrous sodium sulfate (5.2). Transfer to an extraction thimble (6.1) and cover with a fat-free wad of cott
32、onwool. Transfer some silicon carbide chips (5.4) to a dry flask. If the fat has to undergo subsequent quality tests, use glass beads instead of silicon carbide chips. Connect the flask with the extractor to collect the light petroleum extract. Place the thimble in the extractor (6.2) and extract fo
33、r2h with light petroleum (5.3). Regulate the heating apparatus (6.3) to obtain at least10 siphonings per hour if a Soxhlet-type extractor is used, or a reflux rate of at least5drops per second (about10ml/min) if an equivalent apparatus is used. Dilute the light petroleum extract in the flask to500ml
34、 with light petroleum (5.3) and mix well. Weigh (m 1 ), to the nearest1mg, a dry flask containing some silicon carbide chips or glass beads(5.4). Pipette50ml of the light petroleum solution into this flask. 9.2.2 Distil off the solvent until the flask is nearly free from solvent. Add2ml of acetone (
35、5.5) to the flask, swirl and gently warm on the heating apparatus (6.3) to remove the acetone. Blow off the last traces of acetone. Dry the residue for(10 0,1)min in the drying oven (6.4) set at103 C. Cool in the desiccator (6.6) and weigh (m 2 ) to the nearest0,1mg. Alternatively, the following pro
36、cedure may be applied. Distil off the solvent. Dry the residue in the flask for1,5h under vacuum in the oven (6.5) set at 80 C. Leave to cool in the desiccator (6.6) and weigh (m 2 ) to the nearest0,1mg. 9.2.3 Leave the extraction residue from the thimbleto dry in air to eliminate solvent residues.
37、Weigh (m 3 ) the dried residue to the nearest0,1mg. Crush the residue to a particle size of1mm. Proceed in accordance with 9.3. 9.3 Test portion Weigh (m 4 ), to the nearest1mg, 5 g of the prepared test sample (clause 8 or 9.2). For a sample of category B (see clause 1), proceed in accordance with 9
38、.4. For a sample of category A, transfer the test portionto an extraction thimble (6.1) and cover with a fat-free wad of cottonwool. Proceed in accordance with9.5.BS5766-18:1999 BSI 04-2000 3 9.4 Hydrolysis Transfer the test portion to a 400 ml beaker or a300ml conical flask. Add 100 ml of hydrochlo
39、ric acid (5.6) and silicon carbide chips (5.4). Cover the beaker with a watch glass or fit the conical flask with a reflux condensor. Bring the mixture to a gentle boil over a flame or a hot plate and maintain it for1h. Swirl every10min to prevent the product sticking to the sides of the container.
40、Cool to ambient temperature and add a quantity of filtration aid (5.7) sufficient to prevent any loss of fat during the filtration. Filter through a moistened, fat-free double filter paper in a Bchner funnel with suction. Wash the residue with cold water until a neutral filtrate is obtained. CAUTION
41、: If oil or fat appears on the surface of the filtrate, wrong results may be obtained. A possible solution is to repeat the procedure applying a smaller test portion or a higher acid concentration. Carefully take out the filter and place the double filter paper containing the residue in an extractio
42、n thimble (6.1) and dry under vacuum for60min in the oven (6.5) set at80 C. Remove the thimble from the oven and cover with a fat-free wad of cottonwool. 9.5 Extraction 9.5.1 Transfer some silicon carbide chips (5.4) to a dry flask and weigh (m 5 ) to the nearest 1 mg. If the fat has to undergo subs
43、equent quality tests, use glass beads instead of silicon carbide chips. Connect the flask with the extractor to collect the light petroleum extract. Place the thimble in the extractor (6.2) and extract for 6 h with light petroleum (5.3). Regulate the heating apparatus (6.3) to obtain at least10 siph
44、onings per hour if a Soxhlet-type extractor is used, or a reflux rate of at least 5 drops per second (about 10 ml/min) if an equivalent apparatus is used. 9.5.2 Distil off the solvent until the flask is nearly free from solvent. Add 2ml of acetone (5.5) to the flask, swirl and gently warm on the hea
45、ting apparatus (6.3) to remove the acetone. Blow off the last traces of acetone. Dry the residue for(10 0,1)min in the drying oven (6.4) set at103 C. Cool in the desiccator (6.6) and weigh (m 6 ) to the nearest 0,1mg. Alternatively, the following procedure may be applied. Distil off the solvent. Dry
46、 the residue in the flask for1,5h under vacuum in the oven (6.5) set 80 C. Leave to cool in the desiccator (6.6) and weigh (m 6 ) to the nearest 0,1mg. 10 Calculation 10.1 Determination with preliminary extraction (9.2) Calculate the fat content of the test sample, w 1 , in grams per kilogram, using
47、 the equation: where Express the result to the nearest 1 g/kg. 10.2 Determination without preliminary extraction Calculate the fat content of the test sample, w 2 , in grams per kilogram, using the equation: where Express the result to the nearest 1 g/kg. m 0 is the mass of the test sample weighed i
48、n9.2, in grams (g); m 1 is the mass of the flask with silicon carbide chips used in 9.2, in grams (g); m 2 is the mass of the flask with silicon carbide chips and the dried light petroleum extract residue obtained in 9.2, in grams (g); m 3 is the mass of the dried extraction residue obtained in 9.2,
49、 in grams (g); m 4 is the mass of the test portion (9.3), in grams(g); m 5 is the mass of the flask with silicon carbide chips used in 9.5, in grams (g); m 6 is the mass of the flask with silicon carbide chips and dried light petroleum extract residue obtained in 9.5, in grams (g); f is the units correction factor, in grams per kilogram (f = 1000g/kg). m 4 is the mass of the test portion (9.3), in grams(g); m 5 is the mass of the flask with silicon carbide chips used in 9.5, in grams (g); m 6 is the mass of the flask with silicon
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