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1、BRITISH STANDARD BS ISO 6885:2006 Animal and vegetable fats and oils Determination of anisidine value ICS 67.200.10 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 6885:2006 This British Standard was published under the authority of
2、 the Standards Policy and Strategy Committee on 30 June 2006 BSI 2006 ISBN 0 580 48627 3 National foreword This British Standard reproduces verbatim ISO 6885:2006 and implements it as the UK national standard. It supersedes BS EN ISO 6885:2001 which is withdrawn. The UK participation in its preparat
3、ion was entrusted to Technical Committee AW/307, Oilseeds, animal and vegetable fats and oils, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publ
4、ications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the ne
5、cessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the in
6、terpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii and iii, a blank page, pages 1 to
7、7 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number I
8、SO 6885:2006(E) INTERNATIONAL STANDARD ISO 6885 Third edition 2006-06-01 Animal and vegetable fats and oils Determination of anisidine value Corps gras dorigines animale et vgtale Dtermination de lindice danisidine BS ISO 6885:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+
9、00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The w
10、ork of preparing International Standards is normally carried out 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-govern
11、mental, in liaison with ISO, also take part in the work. ISO collaborates 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, Part 2. The
12、 main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
13、 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 6885 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal an
14、d vegetable fats and oils. This third edition cancels and replaces the second edition (ISO 6885:1998), which has been technically revised by changing the equation in Clause 10. BS ISO 6885:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI
15、 blank Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Animal and vegetable fats and oils Determination of anisidine value 1 Scope This International Standard specifies a method for the determination of the anisidine value in animal and ve
16、getable fats and oils. This is a measure of the amount of aldehydes present (principally ,-unsaturated aldehydes). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated refer
17、ences, the latest edition of the referenced document (including any amendments) applies. ISO 661, Animal and vegetable fats and oils Preparation of test sample ISO 3696, Water for analytical laboratory use Specification and test methods 3 Terms and definitions For the purposes of this document, the
18、following terms and definitions apply. 3.1 anisidine value one hundred times the increase in absorbance, measured at a wavelength of 350 nm in a 10 mm cell, of a test solution when reacted with p-anisidine under the test conditions specified in this International Standard NOTE The anisidine value ha
19、s no dimensions, and is calculated and quoted on the basis of 1 g of the test sample in 100 ml of a mixture of solvent and reagent. 4 Principle A test solution is prepared in isooctane (2,2,4-trimethylpentane). It is reacted with an acetic acid solution of p-anisidine. The increase in absorbance at
20、350 nm is measured. The anisidine value is calculated. 5 Reagents Use only reagents of recognized analytical grade, and water complying with grade 3 of ISO 3696. 5.1 Sodium sulfate (Na2SO4), anhydrous. 5.2 Isooctane (2,2,4-trimethylpentane), having an absorbance not exceeding 0,01 against water in t
21、he wavelength range 300 nm to 380 nm. BS ISO 6885:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 5.3 4-Methoxyaniline (p-anisidine), anhydrous cream-coloured crystals. WARNING p-Anisidine is toxic and care shall be taken to avoid con
22、tact with the skin. Store the p-anisidine in a dark bottle at 0 C to 4 C in the dark. No coloration (grey or pink) shall be observed. If this is present, purify the p-anisidine as follows. Dissolve 4 g of p-anisidine in 100 ml of water at 75 C. Add 0,5 g of sodium sulfite (Na2SO3) and 2 g of charcoa
23、l. Stir for 5 min and filter through a medium retention filter paper to give a clear solution. Cool the filtrate to 0 C and leave at this temperature for at least 4 h. Filter off the crystals, preferably under vacuum, and wash with a small volume of water at about 0 C. Dry in a vacuum desiccator con
24、taining an efficient desiccant. 5.4 Glacial acetic acid, of water content not greater than 0,1 % (mass fraction). 5.5 Anisidine reagent On the day of use, prepare the minimum quantity of reagent required for the analysis, in view of its toxicity and limited life. Prepare, for example, 50 ml of reage
25、nt as follows. Dissolve 0,125 g of the p-anisidine (5.3) in the glacial acetic acid (5.4) in a 50 ml volumetric flask and dilute to the mark with the same solvent, avoiding exposure to strong light. Check the absorbance against isooctane before use and discard the reagent when the difference is larg
26、er than 0,2. In any case, discard any reagent left over on the day of use. 6 Apparatus Usual laboratory apparatus and, in particular, the following. 6.1 Spectrometer, double- or single-beam, suitable for use at a wavelength of 350 nm, with cells of optical path length 10 mm. When a double-beam spect
27、rometer is used, it is recommended that a pair of matched 10 mm cells be used. 6.2 Volumetric flasks, of 25 ml capacity. 6.3 Test tubes, of 10 ml capacity, fitted with ground glass stoppers. 6.4 Pipettes, of 1 ml and 5 ml capacities, equipped with a safety suction device. 7 Sampling A representative
28、 sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 5555. 8 Preparation of test sample Prepare the test samp
29、le in accordance with ISO 661. If the moisture content of the sample is greater than 0,10 % (mass fraction), it should be dried using the following procedure. BS ISO 6885:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 Add sodium sulf
30、ate (5.1) in the proportion of 1 g to 2 g per 10 g of the thoroughly mixed sample, at a temperature of not more than 10 C above the melting point in the case of a solid fat. Stir thoroughly and filter, maintaining the temperature to prevent solidification. Take care to exclude extraneous moisture du
31、ring the procedure because it can affect the equilibrium reaction during which water is produced. 9 Procedure 9.1 Test portion and preparation of test solution Weigh, to the nearest 1 mg, a sufficient mass of the prepared test sample (Clause 8) directly into a 25 ml volumetric flask. Preheat solid s
32、amples to 10 C above their melting point. Dissolve the sample in 5 ml to 10 ml of the isooctane (5.2) and make up to the mark with the same solvent. The size of the test portion depends on the quality of the sample and the characteristics of the spectrometer used, and should be chosen to avoid readi
33、ngs near the upper and lower ends of the scale. In general, 0,4 g to 4,0 g is used. 9.2 Unreacted test solution By means of a pipette (6.4), transfer 5 ml of the test solution (9.1) to a test tube (6.3). Add 1 ml of glacial acetic acid (5.4), stopper the tube and shake well. Keep the test tube in th
34、e dark at (23 3) C for 8 min. Within a further 2 min, transfer the solutions to a clean, dry spectrometer cell. After a total reaction time of 10 min 1 min, follow the procedure specified in 9.5. 9.3 Reacted test solution Transfer, by means of a pipette (6.4), 5 ml of the test solution (9.1) to a te
35、st tube (6.3). Add, by means of a pipette (6.4), 1 ml of the anisidine reagent (5.5). Stopper the tube and shake well. Keep the test tube in the dark at (23 3) C for 8 min. Within a further 2 min, transfer the solutions to a clean, dry spectrometer cell. After a total reaction time of 10 min 1 min f
36、rom the addition of the anisidine reagent, follow the procedure specified in 9.5. 9.4 Blank Transfer, by means of a pipette (6.4), 5 ml of isooctane (5.2) to a test tube (6.3). Add, by means of a pipette (6.4), 1 ml of the anisidine reagent (5.5). Stopper the tube and shake well. Keep the test tube
37、in the dark at (23 3) C for 8 min. Within a further 2 min, transfer the solutions to a clean, dry spectrometer cell. After a total reaction time of 10 min 1 min from the addition of the anisidine reagent, follow the procedure specified in 9.5. 9.5 Spectrometric measurement Adjust the zero absorption
38、 of the spectrometer with isooctane (5.2) at 350 nm. Measure the following absorbances against isooctane (5.2): A1 of the reacted solution (9.3), A0 of the unreacted test solution (9.2), and A2 of the blank (9.4). BS ISO 6885:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+0
39、0:00 2006, Uncontrolled Copy, (c) BSI 4 9.6 Absorbance range If the measured absorbance A1 of the reacted solution (9.3) is not in the range 0,2 to 0,8, repeat the determination (9.2 to 9.4) with an adjusted amount of test sample. If the measured absorbance A2 of the blank exceeds 0,2, purify the an
40、isidine reagent as described in 5.3, and prepare fresh anisidine reagent (5.5). Repeat this test with the fresh anisidine reagent. 10 Expression of results 10.1 The anisidine value (AV) of the sample is equal to () 120 100 AV1,2 QV AAA m = where V is the volume in which the test sample is dissolved,
41、 in millilitres (V = 25 ml); m is the mass of the test portion, in grams; Q is the sample content of the measured solution based on which the anisidine value is expressed, in grams per millilitre (Q = 0,01 g/ml); A0 is the absorbance of the unreacted test solution (9.2) A1 is the absorbance of the r
42、eacted solution (9.3); A2 is the absorbance of the blank (9.4); 1,2 is the correction factor for the dilution of the test solution with 1 ml of the reagent or glacial acetic acid. Report the results to 1 decimal place. 10.2 When assessing the oxidative deterioration of an oil, the total oxidation va
43、lue, or totox value (TV), may be helpful. The calculation is the following with the peroxide value (PV) expressed in meq O2/kg: TV = (2 PV) + AV 11 Precision 11.1 Interlaboratory tests Details of two interlaboratory tests on the precision of the method are summarized in Annex A. The values derived f
44、rom these interlaboratory tests may not be applicable to ranges and matrices other than those given. 11.2 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the
45、 same equipment within a short interval of time, will in not more than 5 % of cases exceed the value of r given in Table 1. BS ISO 6885:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 11.3 Reproducibility The absolute difference betwe
46、en two single test results, obtained using the same method on identical test material in two different laboratories with different operators using different equipment, will in not more than 5 % of cases exceed the value of R given in Table 1. Table 1 Repeatability limit (r) and reproducibility limit
47、 (R) Anisidine value Range of variation r R AV (mean of two determinations) 0 to 100 0,034 AV + 0,31 0,19 AV + 1,41 12 Test report The test report shall specify: a) all information necessary for the complete identification of the sample; b) the sampling method used, if known; c) the test method, wit
48、h reference to this International Standard; d) all operating details not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the results; e) the test results obtained; f) if the repeatability has been checked, the final
49、quoted result obtained. BS ISO 6885:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:44 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 6 Annex A (informative) Results of interlaboratory test A recent interlaboratory test carried out at the international level in 2004 by ITERG (France), in which 18 laboratories participated (9 countries: Argentina, Canada, France, Germany, Hungary, Netherlands, Portugal, UK, USA), each performing 2 determinati