1、BRITISH STANDARD BS ISO 10540-2:2003 Animal and vegetable fats and oils Determination of phosphorus content Part 2: Method using graphite furnace atomic absorption spectrometry ICS 67.200.10 BS ISO 10540-2:2003 This British Standard was published under the authority of the Standards Policy and Strat
2、egy Committee on 26 February 2003 BSI 26 February 2003 ISBN 0 580 41313 6 National foreword This British Standard reproduces verbatim ISO 10540-2:2003 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee AW/307, Oil seeds, animal
3、 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 publications referred to in this document may be found in the BSI Cat
4、alogue 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 necessary provisions of a contract. Users are responsible for its c
5、orrect 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 interpretation, or proposals for change, and keep the UK interests
6、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 8, an inside back cover and a back cover. The BSI copyright d
7、ate displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 10540-2:2003(E)INTERNATIONAL STANDARD ISO 10540-2 First edition 2003-02-01 Animal and vegetable fats and oils Determination of phosphorus conten
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13、ofice saCe tsopale 65 eneG 1121-HC 02 av leT. 4 + 10 947 22 1 11 xaF0 947 22 14 + 9 74 E-mial coirypthgis.o gro We bwww.is.o groii BSISO105402:2003 iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The wor
14、k 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-governme
15、ntal, 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 m
16、ain 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. A
17、ttention 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 10540-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal a
18、nd vegetable fats and oils. ISO 10540 consists of the following parts, under the general title Animal and vegetable fats and oils Determination of phosphorus content: Part 1: Colorimetric method Part 2: Method using graphite furnace atomic absorption spectrometry Part 3: Method using inductively cou
19、pled plasma (ICP) optical emission spectroscopy BSISO105402:2003INTENRATIONAL TSANDADR IS-04501 O2:(3002E)1Animal and vegetable fats and oils Determination of phosphorus content Part 2: Method using graphite furnace atomic absorption spectrometry 1 Scope This International Standard specifies a rapid
20、 method for the determination of trace amounts of phosphorus (u 40 mg/kg) in crude or refined animal and vegetable fats and oils (hereafter referred to as fats). The limit of determination of the method is 1,0 mg/kg. 2 Normative references The following referenced documents are indispensable for the
21、 application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 661, Animal and vegetable fats and oils Preparation of test sample ISO 10540-1, Animal and vegetable fats
22、 and oils Determination of phosphorus content Part 1: Colorimetric method 3 Principle A test portion is mixed with a matrix modifier then vaporized in a graphite furnace atomic absorption spectrometer, previously calibrated using standard dilutions of soya lecithin. The phosphorus content is calcula
23、ted from the absorption at a wavelength of 213,5 nm. 4 Reagents Use only reagents of recognized analytical grade, unless otherwise specified. 4.1 Cyclohexane. 4.2 Matrix modifier. Dissolve 1 g of lanthanum organometallic standard with a lanthanum content of 5 000 mg/kg in 10 ml of cyclohexane (4.1).
24、 It is essential that the lanthanum be added for the determination of the total phosphorus content. If it is omitted, the amount of phosphorus determined will vary, depending on the type of phosphatides present in the sample. BSISO105402:20032 NOTE A suitable lanthanum organometallic standard is ava
25、ilable, for example, from Continental Oil Company, Ponca City, Oklahoma, USA (Conostan, 5 000 mg/kg) or from Merck, D-1600 Darmstadt, Germany (metal in standard oil, 1 000 mg/kg) 1) . 4.3 Blank oil: refined liquid edible oil with a phosphorus content below 1 mg/kg. The phosphorus content of the blan
26、k oil may be determined in accordance with ISO 10540-1. 4.4 Soya lecithin (commercial product), well-defined, with a phosphorus content of about 2 % (by mass). 4.5 Standard stock solution, with a phosphorus content of about 400 mg/kg. Dissolve 1 g of soya lecithin (4.4) in 4 g cyclohexane (4.1) and
27、add 45 g of the blank oil (4.3). Determine the phosphorus content in accordance with ISO 10540-1. 4.6 Standard working solutions, with a phosphorus content of 10 mg/kg, 20 mg/kg and 40 mg/kg respectively. Dilute the stock solution (4.5) as appropriate with the blank oil (4.3). NOTE A solution with a
28、 phosphorus content of 1 mg/kg may be useful when analysing palm oil or palm fractions. 4.7 Argon, of purity 99,98 %. If argon is not available, nitrogen may be used as purge gas but it gives lower sensitivity. WARNING At temperatures above 2 300 C nitrogen forms toxic hydrogen cyanide gas, therefor
29、e continuous ventilation shall be provided in the furnace area. 5 Apparatus Usual laboratory apparatus and, in particular, the following. 5.1 Atomic absorption spectrometer, equipped with either “peak height” mode and printer or “continuous” mode and pen recorder (full-scale response in 0,2 s), toge
30、ther with appropriate electrode-less discharge lamp (or hollow cathode lamp) and deuterium background corrector. NOTE A Leeman atomic absorption spectrometer may be used. 1)5.2 Graphite furnace atomizer, placed in the atomic absorption spectrometer (5.1), equipped with a control unit for temperature
31、 programming. 5.3 Graphite tube, uncoated, with or without a pyrolytical platform. In combination with a platform, a pyrolytically coated graphite tube may be used as well. 5.4 Micropipettor, of capacity 20 l. 5.5 Pipettor tips. 5.6 Test tubes, of capacity 10 ml. 5.7 Oven, capable of being maintaine
32、d at 60 C 2 C. 5.8 Autosampler for graphite furnace atomizer (optional), with polyethylene sample cups. 1) These are examples of suitable products available commercially. This information is given for the convenience of users of this part of ISO 10540 and does not constitute an endorsement by ISO of
33、 these products. BSISO105402:2003 36 Sampling It is important that the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage. Sampling is not a part of the method specified in this part of ISO 10540. A recommended sampling method is
34、 given in ISO 5555. Store samples in glass or poly(ethylene terephthalate) (PET) bottles. 7 Preparation of test sample Prepare the test sample in accordance with ISO 661, ensuring that any sediment, which may be rich in phosphorus, is incorporated. 8 Procedure 8.1 Preparation of apparatus 8.1.1 Swit
35、ch on the atomic absorption spectrometer (5.1) and the deuterium background corrector. 8.1.2 In accordance with the manufacturers instructions, adjust the lamp current, the slit, the wavelength and the amplification. The required wavelength for phosphorus is 213,5 nm. 8.1.3 Optimize the position of
36、the graphite furnace atomizer (5.2) in the atomic absorption spectrometer (5.1) and set the required programme on the control unit of the furnace. See Table 1. Table 1 Programme for the graphite furnace programmer Temperature Ramp time Hold time Gas flow Step C s s ml/min 1 600 40 20 300 2 1 600 50
37、40 300 3 2 800 0 5 0 4 2 800 1 3 50 If this programme cannot be realized, use a comparable programme suitable for the particular apparatus. Place the platform, if used, in the graphite tube (5.3). Both atomization off the wall and atomization off the platform may be used. 8.1.4 Before each injection
38、 of a sample solution, pretreat the pipettor tip (5.5) by pipetting and then discarding 20 l of cyclohexane. The film of cyclohexane remaining on the wall of the tip facilitates a reproducible transfer of the sample solution. Inject 20 l of the standard working solution with phosphorus content of 40
39、 mg/kg (4.6) into the graphite furnace using the micropipettor (5.4). Initiate the programme and record the absorption. Repeat these instructions until constant absorption has been reached. Each time a graphite tube is replaced, carry out three determinations with the same standard working solution
40、(4.6) to achieve equilibrium. BSISO105402:20034 8.2 Preconditioning of test sample, blank oil and working solutions At least 15 min before the determination, place the test sample (Clause 7), the blank oil (4.3) and the standard working solutions (4.6) in the oven (5.7). Shake each container vigorou
41、sly immediately before further analysis. If the phosphorus content is greater than 40 mg/kg, dilute the sample with blank oil (4.3). In that case, multiply the observed absorption with the dilution factor. 8.3 Determination 8.3.1 Graphite tube blank Record the absorption, if any, of the graphite tub
42、e as such and auto-zero this absorption. 8.3.2 Blank oil Weight, to the nearest 0,01 g, 1,00 g of the preconditioned blank oil (4.3) in a test tube (5.6). Add 1,00 g of matrix modifier (4.2) and mix thoroughly. Inject 20 l of this mixture into the graphite furnace using the micropipettor (5.4). Init
43、iate the programme and record the absorption. 8.3.3 Calibration of the apparatus Weigh, to the nearest 0,01 g 1,00 g of each of the three preconditioned standard working solutions (4.6) in three test tubes (5.6). To each test tube, add 1,00 g of matrix modifier (4.2) and mix thoroughly. Inject 20 l
44、of the mixture into the graphite furnace using the micropipettor (5.4). Initiate the programme and record the absorption. Repeat until the absorption is constant. 8.3.4 Test sample Weigh, to the nearest 0,01 g, 1,00 g of the preconditioned test sample in a test tube (5.6). Add 1,00 g of matrix modif
45、ier (4.2) and mix thoroughly. Inject 20 l of the mixture into the graphite furnace using the micropipettor (5.4), initiate the programme and record the absorption. 9 Expression of results Measure the peak height on the recorder-chart or take the reading of the display or printer. Draw a calibration
46、curve by plotting the absorption of the three standard working solutions (8.3.3), corrected for the blank (8.3.2), against their phosphorus contents. Read the phosphorus content of the sample from the calibration curve. Express the result in milligrams per kilogram. NOTE With the use of sophisticate
47、d equipment, autocalibration can be applied. BSISO105402:2003 510 Precision 10.1 Interlaboratory test Details of interlaboratory tests on the precision of the method are summarized in Annex A. The values derived from these interlaboratory tests may not be applicable to concentration ranges and matri
48、ces other than those given. 10.2 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 same equipment within a short interval of time, will in not more that 5
49、% of cases be greater than the repeatability limit (r), deduced by linear interpolation from Table 2. 10.3 Reproducibility When the values of two single test results, obtained using the same method on identical test material in different laboratories with different operators using different equipment, lie within the range of the values in Table 1, the absolute difference between the two test results will in not more than 5 % of cases be
