1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58tin content Spectrometric methodICS 67.100.10Milk and canned evaporated milk Determination of DRAFT
2、 FOR DEVELOPMENTDD ISO/TS 9941:2005DD ISO/TS 9941:2005This Draft for Development was published under the authority of the Standards Policy and Strategy Committee on 23 January 2006 BSI 23 January 2006ISBN 0 580 47470 4another 3 years or to withdraw it. Comments should be sent in writing to the Secre
3、tary of BSI Technical Committee AW/5, Chemical analysis of milk and milk products, at British Standards House, 389 Chiswick High Road, London W4 4AL, giving the document reference and clause number and proposing, where possible, an appropriate revision of the text.A list of organizations represented
4、 on this committee can be obtained on request to its secretary.Cross-referencesThe 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 “S
5、earch” 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 correct application.Compliance with a Draft for Development does not of itself confer immunity from le
6、gal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, the ISO/TS title page, pages ii to vi, pages 1 to 6, an inside back cover and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued s
7、ince publicationAmd. No. Date Commentsthat UK experience can be reported to the international organization responsible for the Technical Specification. A review of this publication will be initiated not later than 3 years after its publication by the international organization so that a decision can
8、 be taken on its status at the end of its 3-year life. Notification of the start of the review period will be made in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review period, the responsible BSI Committee will decide whether to s
9、upport the conversion into an international standard, to extend the life of the Technical Specification for National forewordThis Draft for Development reproduces verbatim ISO/TS 9941:2005.This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development se
10、ries of publications and is of a provisional nature because the new edition of the international document has been issued as a Technical Specification and is open to further development. It should be applied on a provisional basis, so that information and experience of its practical application may
11、be obtained.Comments arising from the use of this Draft for Development are requested so Reference numbersISO/TS 9941:2005(E)IDF/RM 160:2005(E)TECHNICAL SPECIFICATION ISO/TS9941IDF/RM160Second edition2005-06-15Milk and canned evaporated milk Determination of tin content Spectrometric method Lait et
12、lait concentr non sucr en bote Dtermination de la teneur en tain Mthode spectromtrique DD ISO/TS 9941:2005ii iiiContents Page Foreword iv Introduction . vi 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 1 5 Reagents 1 6 Apparatus 2 7 Sampling 3 8 Preparation of test s
13、ample. 3 9 Procedure 3 9.1 Test portion and pretreatment. 3 9.2 Mineralization 3 9.3 Colour development . 4 9.4 Blank test. 4 9.5 Preparation of the calibration graph. 4 9.6 Check on tin losses 5 9.7 Spectrometric measurements . 5 9.8 Number of determinations . 5 10 Calculation and expression of res
14、ults 5 10.1 Calculation. 5 10.2 Expression of results . 5 11 Test report . 5 Bibliography . 6 DD ISO/TS 9941:2005iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standa
15、rds 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-governmental, in liaison with ISO, also tak
16、e 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 main task of technical committees is
17、 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. In other circumstances, particularly
18、 when there is an urgent market requirement for such documents, a technical committee may decide to publish other types of normative document: an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an ISO working group and is accepted for publication i
19、f it is approved by more than 50 % of the members of the parent committee casting a vote; an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a vo
20、te. An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is confirmed, it is reviewed again after a further three years, at which time it must
21、either be transformed into an International Standard or be withdrawn. 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/TS 9941IDF/RM 160 was prepa
22、red by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. This second edition cancels and replaces the first edition (ISO/TS 9941IDF/RM 160:2003), which has been technica
23、lly revised. DD ISO/TS 9941:2005vForeword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National Committee in every member country. Every National Committee has the right to be represented on the IDF Standing Committees carrying out the technical work.
24、 IDF collaborates with ISO and AOAC International in the development of standard methods of analysis and sampling for milk and milk products. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the Action Teams and Standing Committees
25、 are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 % of IDF National Committees casting a vote. In other circumstances, particularly when there is an urgent market requirement for such documents, a Standing Committee may d
26、ecide to publish an other type of normative document which is called by IDF: Reviewed method. Such a method represents an agreement between the members of a Standing Committee and is accepted for publication if it is approved by at least 50 % of the committee members casting a vote. A Reviewed metho
27、d is equal to an ISO/PAS or ISO/TS and will, therefore, also be published jointly under ISO conditions. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IDF shall not be held responsible for identifying any or all such patent right
28、s. ISO/TS 9941IDF/RM 160 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. All work was carried out by the Joint ISO/IDF Action Team on Minor compounds,
29、of the Standing Committee on Minor components and characterization of physical properties, under the aegis of its project leaders, Dr M. Carl (DE) and Dr G. Ellen (NL). This second edition cancels and replaces the first edition (ISO/TS 9941IDF/RM 160:2003), which has been technically revised. DD ISO
30、/TS 9941:2005vi Introduction This Technical Specification (Reviewed Method for IDF) specifies a spectrometric method for the determination of tin content in canned evaporated milk. Its limit of determination is 5 mg of tin per kilogram. Despite several attempts, the Joint IDF-ISO Action Team (JAT) o
31、n Minor compounds could not organize a collaborative study with a sufficient number of participating laboratories to be in accordance with ISO 5725-2. Thus no precision figures for repeatability and reproducibility could be established. However, the method has been proven to be reliable by at least
32、three experienced laboratories and particularly with respect to its accuracy. The method was therefore adopted as a Technical Specification rather than as an International Standard. DD ISO/TS 9941:20051Milk and canned evaporated milk Determination of tin content Spectrometric method 1 Scope This Tec
33、hnical Specification (Reviewed Method for IDF) specifies a spectrometric method for the determination of the tin content in canned evaporated milk. The limit of determination of the method is 5 mg/kg. 2 Normative references The following referenced documents are indispensable for the application of
34、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 3696:1987, Water for analytical laboratory use Specification and test methods 3 Terms and definitions For the purposes of
35、 this document, the following terms and definitions apply. 3.1 tin content mass fraction of substances determined by the procedure specified in this Technical Specification NOTE The tin content is expressed in milligrams per kilogram of sample. 4 Principle The organic material is mineralized with a
36、mixture of nitric acid and sulfuric acid. Water, hydrochloric acid and sodium carbonate solution are added. Interfering iron(III) ions are masked with thiourea solution and the tin(IV) is complexed with quercetin. The absorbance of the yellow solution is measured spectrometrically at the wavelength
37、of maximum absorption (437 nm). 5 Reagents Use only reagents of very pure analytical grade which, with the exception of the tin standard solution (5.11), are free from tin. 5.1 Water, double distilled or of equivalent quality, complying with the requirements of ISO 3696:1987, grade 2. 5.2 Ethanol (C
38、H3CH2OH), with volume fraction of about 96 %. 5.3 Diethyl ether (C2H5)2O. DD ISO/TS 9941:20052 5.4 Sulfuric acid, concentrated, 20(H2SO4) = 1,84 g/ml. 5.5 Nitric acid, concentrated, 20(HNO3) = 1,42 g/ml. 5.6 Hydrogen peroxide solution, 20(H2O2) = (1,099 to 1,103) g/ml. Store the hydrogen peroxide so
39、lution in a refrigerator. 5.7 Hydrochloric acid, dilute, c(HCl) = 2,5 mol/l. Dilute 221 ml of concentrated hydrochloric acid 20(HCl) = (1,17 to 1,18) g/ml with water to 1 000 ml and mix. 5.8 Sodium carbonate solution, c(Na2CO3) = 200 g/l. Dissolve 200 g of anhydrous sodium carbonate in water. Dilute
40、 with water to 1 000 ml and mix. 5.9 Thiourea solution, cCS(NH2)2 = 90 g/l. Dissolve 45 g of thiourea in water. Dilute with water to 500 ml and mix. 5.10 Quercetin solution, c(C15H10O7) = 0,75 g/l. Dissolve 750 mg of quercetin (3,3,4,5,7-pentahydroxyflavone) in ethanol (5.2). Dilute with ethanol (5.
41、2) to 1 000 ml and mix. Filter the quercetin solution through a filter paper. Store the solution in the dark for no longer than one week. 5.11 Tin standard solution, c(Sn) = 1,000 g/l. Dilute a commercially available preparation that contains exactly 1,000 g of Sn (e.g. Sn(IV), Titrisol No. 9929 1)i
42、s suitable) with the dilute hydrochloric acid (5.7) to 1 000 ml and mix well. 5.12 Milk, with low tin content, e.g. bottled evaporated milk or whole pasteurised milk. 5.13 Sodium chloride solution (NaCl), containing 0,5 % sodium chloride (mass fraction). 6 Apparatus Keep the clean glassware, includi
43、ng the glass (or quartz) beads (6.5), in 10 % (mass fraction) nitric acid. Rinse the glassware and the beads three times before use with distilled water and then three times with double-distilled water. Dry, if necessary, by successively rinsing with ethanol (5.2) and diethyl ether (5.3). Usual labo
44、ratory equipment and, in particular, the following. 6.1 Analytical balance, capable of weighing to the nearest 1 mg. 6.2 Water baths, capable of operating at 20 C 2 C, at 40 C 2 C, and at between 40 C and 60 C. 6.3 Micro gas burners, which do not emit tin-containing particles, or electric heaters. 6
45、4 Mineralization flasks, (Kjeldahl flasks), of capacity approximately 70 ml, with ground-glass joints (NS 19, with matching glass stoppers), calibrated with a mark on the lower part of the neck at 50 ml. 1) Titrisol No. 9929 is an example of a suitable product available commercially. This informati
46、on is given for the convenience of users of this Technical Specification and does not constitute an endorsement by either ISO or IDF of this product. DD ISO/TS 9941:200536.5 Beads, made of glass or quartz. 6.6 One-mark volumetric flasks, of capacities 50 ml, 500 ml and 1 000 ml. 6.7 Graduated pipett
47、es, of capacities 1 ml, 2 ml and 5 ml, with 0,1 ml graduations. 6.8 One-mark pipettes, capable of delivering 3 ml, 10 ml and 20 ml. 6.9 Micro-pipettes, capable of delivering 10 l, 20 l, 50 l, 100 l and 150 l. 6.10 Spectrometer, capable of measuring absorbance at 437 nm, equipped with glass or quartz
48、 cells of 10 mm optical path length, with polytetrafluoroethylene stoppers. 7 Sampling A representative 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 Technical Specification
49、 A recommended sampling method is given in ISO 707IDF 50. Care should be taken to avoid contamination by tin during sampling. Store glass sampling jars in 10 % (mass fraction) nitric acid. Rinse them thoroughly and dry before use. 8 Preparation of test sample 8.1 Shake the container thoroughly with frequent inversion. Taking care to avoid contamination by tin, open the container and pour out its contents slowly into another pre-cleaned container made of glass and provided with an airtight lid.
