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1、BRITISH STANDARD BS ISO 17240:2004 Fruit and vegetable products Determination of tin content Method using flame atomic absorption spectrometry ICS 67.080.01 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 17240:2004 This British Sta
2、ndard was published under the authority of the Standards Policy and Strategy Committee on 25 November 2004 BSI 25 November 2004 ISBN 0 580 44871 1 National foreword This British Standard reproduces verbatim ISO 17240:2004 and implements it as the UK national standard. Any enquiries on this text shou
3、ld be forwarded to Head of International Content, Standards Development, BSI, 389 Chiswick High Road, London W4 4AL, who will present to the responsible international/European committee any such enquiries on the interpretation, or proposals for change, and keep UK interests informed. Cross-reference
4、s The British Standards which implement international publications 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 Onlin
5、e. This publication does not purport to include all the necessary 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. Summary of pages This document comprises a front cover, an insi
6、de front cover, the ISO title page, pages ii and iii, a blank page, pages 1 to 5 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, Mo
7、n Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 17240:2004(E) OSI 4002 INTERNATIONAL STANDARD ISO 17240 First edition 2004-10-01 Fruit and vegetable products Determination of tin content Method using flame atomic absorption spectrometry Produits drivs des fruits et
8、lgumes Dtermination de la teneur en tain Mthode par spectromtrie dabsorption atomique avec flamme BS ISO 17240:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS:04271 O4002(E) DPlcsid Fremia ihTs PDF file may ctnoian emdebt dedyfepcaes
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14、O4002(E) I SO 4002 All irthgs ersedevr 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 through ISO technical committees. Each member
15、 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 collaborates closely with the International Elect
16、rotechnical 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 main task of technical committees is to prepare International Standards. Draft International Standards adopte
17、d 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. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
18、 rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 17240 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 3, Fruit and vegetable products. BS ISO 17240:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:
19、00 2006, Uncontrolled Copy, (c) BSI blank 4002:04271 OSI SB Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTENRATIONAL TSANDADR IS:04271 O4002(E) I SO 4002 All irthgs ersedevr 1 Fruit and vegetable products Determination of tin content Me
20、thod using flame atomic absorption spectrometry 1 Scope This International Standard specifies an atomic absorption spectrometric method for the determination of the tin content of fruit and vegetable products in the concentration range 10 mg/kg to 500 mg/kg. It is a rapid method, especially suitable
21、 for routine determinations of tin in canned fruits and vegetables contaminated with tin which has migrated from the can. The method can be applied with the prescribed amount of sample to products with a maximum total dry matter content of 30 %. Products with higher contents of total solids can be a
22、nalysed using smaller amounts of sample after corresponding dilution with deionized water. NOTE The method of tin determination in fruit and vegetables products is based on NMKL method No 126/1988 (reference 1 in Annex A). 2 Principle Fruit and vegetable products are digested in hydrochloric acid at
23、 80 C and the tin content is determined by flame atomic absorption spectrometry. 3 Reagents Use only reagents of recognized analytical grade, unless otherwise specified, and deionized water or water of equivalent purity. 3.1 Hydrochloric acid, concentrated (20 = 1,19 g/ml). 3.2 Hydrochloric acid, di
24、lute (c = 6 mol/l). Dilute 50 ml of hydrochloric acid (3.1) with water to 100 ml. 3.3 Tin, standard solution corresponding to 1,0 mg of tin per millilitre. 4 Apparatus Usual laboratory apparatus and, in particular, the following. 4.1 Mechanical grinder, the inside and the blades of which are coated
25、with polytetrafluoroethylene (PTFE). 4.2 Block thermostat, or other device for rapid heating and temperature control. The required temperature accuracy is 3 C. 4.3 Atomic absorption spectrometer, provided with a nitrous oxide/acetylene burner (5 cm), suitable for measurements at a wavelength of 235,
26、5 nm. 4.4 Tin lamp, hollow cathode lamp or electrodeless discharge lamp (EDL). BS ISO 17240:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS:04271 O4002(E) 2 I SO 4002 All irthgs ersedevr NOTE The detection limit of the method is sign
27、ificantly lower when EDL lamps are used. 4.5 Filter paper, Schleicher and Schull 589/1 (Black band)1) or equivalent. 4.6 Analytical balance. 5 Sample A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. 6 Procedure 6
28、.1 Preparation of test sample Thoroughly mix the laboratory sample. If necessary, first remove any seeds, stalks and hard seed-cavity walls, and then grind in the mechanical grinder (4.1). Frozen or deep-frozen products shall be previously thawed in a closed vessel, and the liquid formed during this
29、 process shall be added to the product before mixing. 6.2 Test portion Weigh, to the nearest 0,001 g, 5 g of the test sample (6.1) into a glass tube suitable for the block thermostat (4.2) or directly into a 50 ml volumetric flask. 6.3 Decomposition Add 10 ml of dilute hydrochloric acid (3.2). Incub
30、ate the sample for 60 min in a block thermostat or in a water bath preheated to 80 C 3 C. Stir the mixture three or four times during the heating period. Transfer the sample quantitatively to a 50 ml volumetric flask and, after cooling, dilute to volume with water. Filter the sample through filter p
31、aper (4.5). The filtrate is now ready for measurement by atomic absorption spectrometry. Perform the determination preferably within 5 h to 6 h, or alternatively store the extract in a sealed plastic flask. 6.4 Blank test Carry out a blank test by transferring 10 ml of dilute hydrochloric acid (3.2)
32、 into a glass tube or a volumetric flask and use the same decomposition procedure (6.3) as for the test portion (6.2). 6.5 Determination 6.5.1 Preparation of the calibration graph Dilute the standard tin solution (3.3) adding 10 ml of concentrated hydrochloric acid (3.1) per 100 ml, to obtain an app
33、ropriate number of standard solutions in the range 3,0 mg/l to 200 mg/l, when using a hollow cathode lamp, and in the range 1,0 mg/l to 200 mg/l, when using an EDL lamp. 1) Schleicher and Schull 589/ (Black Band) is an example of a suitable product available commercially. This information is only gi
34、ven for the convenience of users of this International Standard and does not constitute an endorsement by ISO of this product. BS ISO 17240:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS:04271 O4002(E) I SO 4002 All irthgs ersedevr
35、3 Ignite the nitrous oxide/acethylene flame of the atomic absorption spectrometer (4.3) according to the instrument instructions and adjust the gas flow to give a 2 cm red band above the burner head. Aspirate each of these solutions, in turn, into the flame of the spectrometer (4.3). Use a mixture o
36、f dilute hydrochloric acid with water (1 + 9) as a blank. Record the corresponding values of absorbance and plot the calibration graph (absorbance against tin concentration in milligrams per litre). 6.5.2 Spectrometric measurement Set the instrument to the previously established optimum conditions,
37、using the nitrous oxide/acethylene flame and a 235,5 nm resonant wavelength. Aspirate the test solution (6.3) and the blank solution (6.4) into the flame of the spectrometer (4.3). Record the corresponding absorbances. 7 Calculation The tin content of the sample, w, expressed in milligrams per kilog
38、ram of the product, is given by the equation: b ()50 w m = where is the tin concentration of the test solution, expressed in milligrams per litre, read from the calibration graph; b is the tin concentration of the blank test solution, expressed in milligrams per litre, read from the calibration grap
39、h; m is the mass, in grams, of the test portion. 8 Precision 8.1 General The precision of the method has been checked by collaborative studies (13 laboratories) of tin determinations in two samples of tomato soup and two samples of apple sauce (Reference 1 in Annex A). Statistical parameters are exp
40、ressed according to ISO 5725-2 (Reference 2 in Annex A). 8.2 Repeatability 8.2.1 Tomato soup Sample 1: the repeatability coefficient of variation is 4,3 %. Sample 2: the repeatability coefficient of variation is 2,4 %. BS ISO 17240:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25
41、 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS:04271 O4002(E) 4 I SO 4002 All irthgs ersedevr 8.2.2 Apple sauce Sample 1: the repeatability coefficient of variation is 1,078. Sample 2: the repeatability coefficient of variation is 0,406. NOTE The coefficient is dependent on the content of tin in the
42、 sample, and decreases with increasing tin content. 8.3 Reproducibility 8.3.1 Tomato soup Sample 1: the reproducibility coefficient of variation is 12,0 %. Sample 2: the reproducibility coefficient of variation is 7,1 %. 8.3.2 Apple sauce Sample 1: the reproducibility coefficient of variation is 9,4
43、 %. Sample 2: the reproducibility coefficient of variation is 4,0 %. NOTE The coefficient is dependent on the content of tin in the sample, and decreases with increasing tin content. 9 Test report The test report shall specify: a) all information necessary for the complete identification of the samp
44、le; b) the sampling method used; c) the test method used, with 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 test result(s); e) the test re
45、sult(s) obtained, or, if the repeatability has been checked, the final quoted result obtained. BS ISO 17240:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS:04271 O4002(E) I SO 4002 All irthgs ersedevr 5 Bibliography 1 Nordic Committe
46、e on Food Analysis. No 126/1988. Tin. Determination by atomic absorption in fruits and vegetables 2 ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method B
47、S ISO 17240:2004 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:40:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 17240:2004 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. I
48、t presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim
49、 of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: +44 (0)20 8996 9000. Fax: +44 (0)20 8996 7400. BSI offers members an individual updating service called PLUS which ensures that subscribe