1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58(CRMs) ICS 73.060.10Iron ores Guidelines for the use of certified reference materials BRITISH STAND
2、ARDBS ISO 16042:2007BS ISO 16042:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2007 BSI 2007ISBN 978 0 580 50781 6Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its correct applicatio
3、n.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 16042:2007.The UK participation in its preparation was entrusted to Technical Committee ISE/58, Iron ores. A list of orga
4、nizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference numberISO 16042:2007(E)INTERNATIONAL STANDARD ISO16042First edition2007-02-01Iron ores Guidelines for the use of certified refe
5、rence materials (CRMs) Minerais de fer Lignes directrices pour lutilisation des matriaux de rfrence certifis BS ISO 16042:2007ii iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 1 5 Ore types . 2 6 Mass-fraction difference 2 7
6、 Extraction of the test portion. 2 8 Two-bottle strategy. 3 9 Alteration of the CRM . 3 10 Shewhart control charts. 3 11 Acceptance of analytical values 4 12 Test report . 4 Annex A (informative) Example of the calculation of mass-fraction difference 5 BS ISO 16042:2007iv Foreword ISO (the Internati
7、onal 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 body interested in a subject for which a technical committee has been
8、 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 Electrotechnical Commission (IEC) on all matters of electrotechnical standa
9、rdization. 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 adopted by the technical committees are circulated to the member bodies for
10、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 rights. ISO shall not be held responsible for identifying any or all
11、such patent rights. ISO 16042 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron, Subcommittee SC 2, Chemical analysis. BS ISO 16042:2007vIntroduction This International Standard is intended for use in conjunction with other International Standards for the chemical anal
12、ysis of iron ores. It describes recommended procedures for the use of iron ore certified reference materials (CRMs) in verifying the trueness of chemical analysis. It is recommended that CRMs also be used for general quality assurance purposes in laboratories where the analysis of iron ores is carri
13、ed out regularly. It is also recommended that CRMs be, from time to time, introduced as unknowns in laboratory proficiency testing schedules. BS ISO 16042:2007blank1Iron ores Guidelines for the use of certified reference materials (CRMs) 1 Scope This International Standard describes recommended proc
14、edures for the use of CRMs that have been prepared and certified in accordance with ISO 11459. Such CRMs are used by laboratories to carry out the trueness tests as specified in the various International Standards for the chemical analysis of iron ores, to verify the analysis of shipment samples and
15、 the ongoing reliability of analytical results. 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 references, the latest edition of the referenced document (including any
16、 amendments) applies. ISO 3082, Iron ores Sampling and sample preparation procedures ISO 8258:1991, Shewhart control charts ISO 11459, Iron ores Certified reference materials Preparation and certification for use in chemical analysis ISO 11323, Iron ore and direct reduced iron Vocabulary ISO Guide 3
17、0, Terms and definitions used in connection with reference materials ISO Guide 33, Uses of certified reference materials ISO Guide 35, Reference materials General and statistical principles for certification 3 Terms and definitions For the purposes of this document, the terms and definitions given i
18、n ISO 11323 and ISO Guide 30 apply. 4 Principle The uses of CRMs as specified in this document are as follows: a) to verify the trueness of analysis of shipment samples that are used to determine the commercial value of a cargo or any specified quantity of iron ore sampled according to ISO 3082 and
19、delivered from the vendor to the purchaser; b) to demonstrate the ongoing ability of a laboratory to provide analysis of a defined accuracy and precision; c) to test the proficiency of a laboratory to carry out the chemical analysis of iron ores. BS ISO 16042:20072 The use of CRMs for the purpose of
20、 standardization of titrants, or calibration of analytical equipment, is specifically excluded. Further uses of certified reference materials are outlined in ISO Guide 33. 5 Ore types International Standards for the chemical analysis of iron ores specify that the certified reference material be of a
21、 mineralogical ore type similar to the sample whose chemical constituents are to be determined. The mass-fraction ranges of the elements to be determined between the CRM and the test sample should be as specified in Clause 6. The contributing ore sources derived from single or multiple mines, blende
22、d to produce a traded iron ore, may exhibit widely varying characteristics. It is therefore recommended that producers of iron ore are pro-active in ensuring that the blend of iron ores produced for international trade is represented by a specific CRM. Ideally, each traded ore type should be represe
23、nted, with elemental mass fractions close to typical. Procedures for the certification of CRMs in general are given in ISO Guide 35, and procedures for the certification of iron ore CRMs in particular are given in ISO 11459. 6 Mass-fraction difference The allowable absolute differences in mass fract
24、ions of various elements between the test sample and the CRM can be calculated using the following equation for elemental mass fractions up to 10 %: sscs( 10,771ln 25,4)200CCRC+= where Rcis the mass-fraction range; Csis the mass fraction of sample. An example of the calculation of mass-fraction diff
25、erence is given in Annex A. It is recommended that, for the mass fraction of total iron (% Fe), the CRM should not vary by more than 0,5 % Fe from the mass fraction of the test sample. 7 Extraction of the test portion Iron ore CRMs are usually sold in 100 g lots. Typically, for the purpose of analys
26、is, a test portion of 0,38 g to 1,00 g in mass is used. The extraction of the test portion is basically a sampling exercise, which should be carried out on the full quantity of the unit mass by which the CRM is supplied. The extraction of test portions from a diminishing quantity out of one bottle i
27、s not recommended. It is recommended that the total contents of the bottle of CRM prior to its first use be divided into portions that match the intended test portions. Each portion shall be packed in an inert plastic or glass sealed container, with a tightly fitting screw-cap plastic lid, preferabl
28、y with a plastic insert in the top of the bottle, or a heavy-duty plastic bag or vial having a tightly fitting lid. Plastic containers and caps/inserts should be checked to ensure that the electrostatic properties of the plastic do not cause particles to stick selectively to the plastic, thereby cau
29、sing segregation of the material. Bottles shall not have lids with cardboard inserts, as these can cause contamination of the samples. Samples shall not be packed in paper bags, as the paper can contaminate samples used for low levels of certain elements. Containers should be labelled as follows: BS
30、 ISO 16042:20073a) identification by name or number of the CRM; b) the serial number of the bottle in which the CRM was supplied; should the CRM manufacturer not have supplied a bottle number, it is recommended that the laboratory give each bottle its own number; c) the serial number of the test por
31、tion as extracted. EXAMPLE JSS 820-2/100/5 represents the fifth portion extracted out of bottle 100 from CRM JSS 820-2. The division of the CRM shall be effected by rotary sample division or riffle splitter division. In each case, the minimum increments represented in a test portion should be 15 to
32、20 in number. To minimize bias in sampling, test portions shall be taken at random. 8 Two-bottle strategy The number of replicate analyses carried out on a CRM shall be a minimum of two. It is recommended that a duplicate be derived from separate bottles of the CRM. 9 Alteration of the CRM Alteratio
33、ns to the mass fractions of the various certified data of a CRM can occur in a number of ways. The strategy outlined in Clause 7 assists in avoiding this problem or at least limiting it to a single occurrence. The two-bottle strategy (Clause 8) assists in the detection of the above. Good housekeepin
34、g is a basic laboratory requirement and should be in evidence in all laboratories. The following rules apply: a) magnetic spatulas and magnetized equipment shall not be used; b) electrostatically charged equipment shall be discharged or its use avoided; c) containers used for storage of CRMs shall n
35、ot exhibit electrostatic surface charges; d) vibrating spatulas shall not be used for dispensing test portions; e) CRMs shall not be stored in drying ovens; f) platinum ware used for fusions shall be clean and shall not cause any contamination; g) glassware used in analytical determinations shall be
36、 clean and not cause contamination; h) exposure to acid and other vapours shall be avoided; i) storage in places subject to vibrations shall be avoided. In all cases, CRMs shall be stored in accordance with manufacturers recommendations. 10 Shewhart control charts For each CRM used on a regular basi
37、s within a laboratory, Shewhart control charts shall be constructed in accordance with ISO 8258. Separate charts should be constructed for bottle 1 and bottle 2 or the different bottles should be identifiable on the chart. Whilst the trueness test for each use of the CRM still applies, the use of th
38、e Shewhart chart is recommended to identify outliers, trends and runs along the principles outlined in ISO 8258:1991, Figure 2 “Tests for assignable causes”. The Shewhart chart should be updated for every newly completed analysis of the CRM. BS ISO 16042:20074 11 Acceptance of analytical values The
39、result obtained for the certified reference material shall be such that the difference between this result and the certified value of the certified reference material is statistically insignificant. For a certified reference material that has been analysed by at least 10 laboratories using method(s)
40、 that are comparable in both accuracy and precision, the following condition may be used to test the significance of the difference: 22 wcLc 22wc dcLc2SSnAANn+u where Acis the certified value; A is the result or the mean of results obtained for the certified reference material; SLcis the between-lab
41、oratories standard deviation of the certifying laboratories; Swcis the within-laboratory standard deviation of the certifying laboratories; nwcis the average number of replicate determinations in the certifying laboratories; Ncis the number of certifying laboratories; n is the number of replicate de
42、terminations on the reference material (it is recommended that n = 2 as a minimum); Lis the between-laboratory standard deviation, as derived from the precision equations of an ISO/TC102/SC 2 analytical method; dis the within-laboratory standard deviation, as derived from the precision equations of
43、the relevant analytical method. If the condition is satisfied, i.e. if the left-hand side is less than or equal to the right-hand side, then the difference Ac A is statistically insignificant; otherwise it is statistically significant. If the difference is significant, the analysis shall be repeated
44、 simultaneously with an analysis of the test sample. If the difference is again significant, the procedure shall be repeated using a different certified reference material of the same type of ore. If the range of the two values for the test sample is outside the independent duplicate limit calculate
45、d according to the International Standard being used, one or more additional tests shall be carried out. Acceptability of the results for the test sample shall, in each case, be subject to the acceptability of the results for the certified reference material. It is not recommended that reference mat
46、erials that have only been certified by one laboratory be used. 12 Test report The analytical results of a CRM used to verify the analysis of a shipment sample shall be reported, together with the data obtained on the shipment sample if requested by the trading parties. The laboratory shall keep tra
47、ceable records of CRM test results. BS ISO 16042:20075Annex A (informative) Example of the calculation of mass-fraction difference Substituting the analyte mass-fraction range with 0,235 %: c( 10,771 ln (0,235) 25,4) 0,2350,235 %200R += Solving for the natural logarithm of 0,235: c( 10,771 ( 1,488 2
48、) 25,4) 0,2350,235 %200R += Solving the numerator: c9,634 60,235 %200R = Solving for the mass-fraction range gives: c0,235 0,048 %R = Thus, at an analyte mass fraction of 0,235 %, the CRM mass fraction should preferably lie between 0,187 % and 0,283 %. BS ISO 16042:2007BS ISO BSI389 Chiswick High Ro
49、adLondonW4 4AL16042:2007BSI British Standards InstitutionBSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.RevisionsBritish 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 of BSI to improve the quality of our products and services. We would be gra
