1、BS ISO 15238:2016Solid mineral fuels Determination of totalcadmium content of coalBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 15238:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 15238:2016. It supersedes BS ISO
2、 15238:2003 which is withdrawn. The UK participation in its preparation was entrusted to TechnicalCommittee PTI/16, Solid mineral fuels.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovi
3、sions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016. Published by BSI Standards Limited 2016ISBN 978 0 580 92523 8ICS 73.040Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published un
4、der the authority of theStandards Policy and Strategy Committee on 30 November 2016.Amendments/Corrigenda issued since publicationDate Text affectedBS ISO 15238:2016 ISO 2016Solid mineral fuels Determination of total cadmium content of coalCombustibles minraux solides Dosage du cadmium total dans le
5、 charbonINTERNATIONAL STANDARDISO15238Second edition2016-11-15Reference numberISO 15238:2016(E)BS ISO 15238:2016ISO 15238:2016(E)ii ISO 2016 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication
6、may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of t
7、he requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 15238:2016ISO 15238:2016(E)Foreword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Reagents 16 App
8、aratus . 27 Preparation of sample 28 Procedure. 38.1 Ashing of coal sample 38.2 Preparation of test solution . 38.3 Preparation of blank solution 38.4 Graphite-furnace atomic absorption analysis 38.4.1 Calibration . 38.4.2 Measurement of standards . 38.4.3 Measurement of test solution . 48.4.4 Measu
9、rement of blank solution 49 Expression of results 49.1 Ash content 49.2 Cadmium content 410 Precision . 510.1 Repeatability limit 510.2 Reproducibility critical difference . 511 Test report . 5 ISO 2016 All rights reserved iiiContents PageBS ISO 15238:2016ISO 15238:2016(E)ForewordISO (the Internatio
10、nal 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
11、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 standar
12、dization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance
13、 with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).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. Details of a
14、ny patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsemen
15、t.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.The c
16、ommittee responsible for this document is ISO/TC 27, Solid mineral fuels, Subcommittee SC 5, Methods of analysis.This second edition cancels and replaces the first edition (ISO 15238:2003), of which it constitutes a minor revision. This document incorporates changes related to dated references and o
17、ther minor items following its systematic review.iv ISO 2016 All rights reservedBS ISO 15238:2016INTERNATIONAL STANDARD ISO 15238:2016(E)Solid mineral fuels Determination of total cadmium content of coal1 ScopeThis document specifies a procedure for the determination of the total cadmium content of
18、coal.This procedure has not been validated with coals that spontaneously ignite. Prior to use with such sample types, users should validate the method.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of
19、 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 1170, Coal and coke Calculation of analyses to different basesISO 3696, Water for analytical laboratory use Specification
20、 and test methodsISO 5068-2, Brown coals and lignites Determination of moisture content Part 2: Indirect gravimetric method for moisture in the analysis sampleISO 5069-2, Brown coals and lignites Principles of sampling Part 2: Sample preparation for determination of moisture content and for general
21、analysisISO 13909-4, Hard coal and coke Mechanical sampling Part 4: Coal Preparation of test samples3 Terms and definitionsNo terms and definitions are listed in this document.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: avail
22、able at http:/www.electropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp4 PrincipleThe coal sample is ashed, followed by dissolution of the ash in a mixture of hydrochloric, nitric and hydrofluoric acids. The cadmium species present are quantified by graphite furnace atom
23、ic absorption spectroscopy.5 ReagentsWARNING Care should be exercised when handling the reagents, many of which are toxic and corrosive.During the analysis, unless otherwise stated, use only reagents of recognized analytical grade.5.1 Water, conforming to the requirements of Grade 1 of ISO 3696. ISO
24、 2016 All rights reserved 1BS ISO 15238:2016ISO 15238:2016(E)5.2 Aqua regia solution. Mix 1 part by volume of concentrated nitric acid solution (relative density 1,42), 3 parts of concentrated hydrochloric acid solution (relative density 1,19), and 1 part water.5.3 Concentrated hydrofluoric acid sol
25、ution (relative density 1,15).WARNING Hydrofluoric acid is an extremely aggressive chemical which shall be handled with care.5.4 Boric acid solution, saturated. Dissolve 60 g of boric acid in 1 l of hot water, cool and allow to stand for 3 d before decanting the clear solution.5.5 Cadmium standard s
26、tock solution, 10 g/ml. Prepare the stock solution from a high purity metal oxide or salt, having a purity greater than 99,9 %. Dilute to volume with 1 % (V/V) nitric acid solution.The cadmium standard stock solution may also be prepared from commercially available certified cadmium solution.5.6 Cad
27、mium standard solution, 0,1 g/ml. Dilute 10,0 ml of cadmium standard stock solution (5.5) to 1,0 l with 1 % (V/V) nitric acid solution.6 Apparatus6.1 Balance, capable of weighing to the nearest 0,1 mg.6.2 Silica or platinum combustion crucible (45 mm 35 mm 14 mm).6.3 Muffle furnace, with a temperatu
28、re control.6.4 Plastics bottles, made of high density polyethylene (HDPE) or fluorinated ethylene propylene (FEP), of 125 ml capacity, with screw-cap lids, capable of withstanding 130 C when sealed and containing liquid.6.5 Volumetric flasks, made of high density polyethylene (HDPE) or fluorinated e
29、thylene propylene (FEP), of 100 ml capacity.6.6 Boiling-water bath.6.7 Graphite-furnace atomic absorption spectrometer, with background correction.7 Preparation of sampleThe test sample is the general analysis test sample prepared in accordance with ISO 5069-2 or ISO 13909-4 as appropriate. Ensure t
30、hat the moisture content of the sample is in equilibrium with the laboratory atmosphere, exposing it if necessary, in a thin layer for the minimum time required to achieve equilibrium.Before commencing the determination, mix the equilibrated sample for at least 1 min, preferably by mechanical means.
31、If the results are to be calculated other than on the “air-dried” basis (see Clause 9), then, after weighing the test portion, determine the moisture content of a further portion of the test sample by the method described in ISO 5068-2 as appropriate.2 ISO 2016 All rights reservedBS ISO 15238:2016IS
32、O 15238:2016(E)8 Procedure8.1 Ashing of coal sampleWeigh, to the nearest 0,1 mg, the amount of sample necessary to obtain a minimum of 0,2 g ash in one or more open 50 ml silica combustion crucibles (6.2). The coal layer in the crucible shall not exceed a thickness of 0,15 g/cm2. Place the crucibles
33、 in a cold muffle furnace (6.3), set to attain (450 10) C in about 1 h, and maintain at that temperature for a further 2 h. After cooling and weighing, calculate the percentage of ash in the coal. Carefully mix the ash in the crucibles before transferring it to a sample bottle.NOTE The ashing time o
34、f 3 h is a minimum. Ashing overnight (18 h) is allowed.8.2 Preparation of test solutionPlace approximately 0,2 g ( 0,1 mg) of ash in a 125 ml plastics bottle (6.4). Add 3 ml of aqua regia (5.2), 5 ml of concentrated hydrofluoric acid solution (5.3), and tighten the screw cap. Place the bottle on a b
35、oiling water bath for 2 h. Remove the bottle and allow it to cool to ambient temperature, cautiously open, then add 50 ml of saturated boric acid solution (5.4). Warm again for approximately 1 h; if a residue remains at this stage, it may be ignored. Remove the bottle from the water bath and cool ag
36、ain to ambient temperature before transferring the solution quantitatively to a 100 ml plastics volumetric flask, and diluting to 100 ml with water.Care should be exercised when adding the acid mixture to the ash since the 450 C ashing temperature may not have decomposed all carbonates present in th
37、e coal.If desired, it is permitted to prepare the solutions gravimetrically, adjusting the calculations in the appropriate manner.NOTE As an alternative method for the dissolution of the prepared ash, microwave dissolution or acid dissolution in a pressurized vessel can be used, if quantitative reco
38、very of cadmium can be demonstrated.8.3 Preparation of blank solutionPrepare a blank solution by following exactly the dissolution procedure described above (see 8.2) but omitting the coal (ash) sample.8.4 Graphite-furnace atomic absorption analysis8.4.1 CalibrationPrepare standards by diluting aliq
39、uot portions of the cadmium standard solution (5.6), 3 ml of aqua regia solution (5.2), 5 ml of concentrated hydrofluoric acid solution (5.3) and 50 ml of saturated boric acid solution (5.4) to 100 ml with water.Standards containing 0,0 g/l, 1,0 g/l, 2,5 g/l and 5,0 g/l have been found suitable. The
40、 standards used should be verified for each instrument.8.4.2 Measurement of standardsMeasure the absorbance of each standard solution using the graphite-furnace atomic absorption spectrometer (6.7). Plot the corresponding absorbance response for each matrix-matched standard against concentration, pr
41、oducing a calibration curve for the instrument. Sample responses are then compared directly with the calibration.The performance of the instrument shall be verified by the analysis of certified reference materials.NOTE 1 No additional matrix modifier is used for cadmium determination and the instrum
42、ent parameters allow for this by using a low char temperature. ISO 2016 All rights reserved 3BS ISO 15238:2016ISO 15238:2016(E)NOTE 2 An alternative quantification procedure is the use of standard analyte additions to the final solution.8.4.3 Measurement of test solutionRepeat the procedure describe
43、d in 8.4.2 for the test solution (see 8.2). Determine the cadmium concentration in the test solution using the calibration graph (see 8.4.2).8.4.4 Measurement of blank solutionRepeat the procedure described in 8.4.2 for the blank (see 8.3). Determine the cadmium concentration in the blank solution u
44、sing the calibration graph (see 8.4.2).9 Expression of results9.1 Ash contentCalculate the ash content, A, as a percentage by mass of the coal sample, using Formula (1):Acaba=()()mmmm100 (1)wheremais the mass of the ashing combustion crucible;mbis the mass of the ashing combustion crucible plus coal
45、 before ashing;mcis the mass of the ashing combustion crucible plus coal after ashing.9.2 Cadmium contentCalculate the cadmium content, Cd, in ng/g, in the coal test sample using Formula (2):Cd Atb=()10001000m(2)whereAis the ash content of the sample as analysed, in percentage by mass;tis the cadmiu
46、m concentration of the test solution, in g/l;bis the cadmium concentration of the blank solution, in g/l;m is the mass of the sample as analysed, in grams.Report the result as the mean of duplicate determinations to the nearest 20 ng/g on the “as analysed” basis.For calculation of the results to bas
47、es other than “as analysed”, see ISO 1170.4 ISO 2016 All rights reservedBS ISO 15238:2016ISO 15238:2016(E)10 Precision10.1 Repeatability limitThe means of the results of duplicate determinations, carried out at different times, in the same laboratory, by the same operator, with the same apparatus, o
48、n representative portions taken from the same general analysis sample, should not differ by more than the value given in Table 1.10.2 Reproducibility critical differenceThe results of duplicate determinations, carried out in each of two laboratories, on representative portions taken from the same an
49、alysis sample after the last stage of sample preparation, should not differ by more than the value given in Table 1.Table 1Maximum acceptable differences between results obtained (calculated to the same moisture content)Repeatability limitReproducibility critical differenceCadmium content (ng/g) 0,16Cd 1 0,22Cd+ 311 Test reportThe test report shall include the following information:a) identification of the sample tested;b) the method used by reference to this document, i.e. ISO 15238;c) the
