1、BS ISO 11723:2016Solid mineral fuels Determination of arsenic andselenium Eschkas mixtureand hydride generationmethodBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 11723:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of I
2、SO 11723:2016. It supersedes BS ISO 11723:2004 which is withdrawn.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 purpor
3、t to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016. Published by BSI Standards Limited 2016ISBN 978 0 580 92526 9ICS 73.040Compliance with a British Standard cannot confer immunity fromlegal obligations.Thi
4、s British Standard was published under the authority of theStandards Policy and Strategy Committee on 30 November 2016.Amendments/Corrigenda issued since publicationDate Text affectedBS ISO 11723:2016 ISO 2016Solid mineral fuels Determination of arsenic and selenium Eschkas mixture and hydride gener
5、ation methodCombustibles minraux solides Dosage de larsenic et du slnium Mlange dEschka et mthode par production dhydrureINTERNATIONAL STANDARDISO11723Second edition2016-11-15Reference numberISO 11723:2016(E)BS ISO 11723:2016ISO 11723:2016(E)ii ISO 2016 All rights reservedCOPYRIGHT PROTECTED DOCUMEN
6、T ISO 2016, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication 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 per
7、mission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the 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 11723:2016ISO 117
8、23:2016(E)Foreword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Reagents 26 Apparatus . 37 Preparation of the test sample . 38 Procedure. 38.1 Blank determination 38.2 Preparation of test solution . 38.3 Preparation of calibration standards . 48.4 Preparation for me
9、asurement . 48.4.1 General 48.4.2 Arsenic 48.4.3 Selenium 49 Measurement by atomic absorption or atomic fluorescence spectrometry after hydride generation . 410 Expression of results 511 Precision . 511.1 Repeatability . 511.2 Reproducibility critical difference . 612 Test report . 6 ISO 2016 All ri
10、ghts reserved iiiContents PageBS ISO 11723:2016ISO 11723:2016(E)ForewordISO (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 com
11、mittees. 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 take part in the work. ISO collaborates closely with the
12、 International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.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 th
13、e different types of ISO documents should be noted. This document was drafted in accordance 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. IS
14、O shall not be held responsible for identifying any or all such patent rights. Details of any 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 docum
15、ent is information given for the convenience of users and does not constitute an endorsement.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 T
16、echnical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.The committee responsible for this document is ISO/TC 27, Solid minerals fuels, Subcommittee SC 5, Methods of analysis.This second edition cancels and replaces the first edition (ISO 11723:2004), which has been tec
17、hnically revised. This document incorporates changes related to dated references and other minor items following its systematic review.iv ISO 2016 All rights reservedBS ISO 11723:2016INTERNATIONAL STANDARD ISO 11723:2016(E)Solid mineral fuels Determination of arsenic and selenium Eschkas mixture and
18、 hydride generation method1 ScopeThis document specifies a method using Eschkas mixture during ashing, extraction of the ash residue with acid, and hydride generation atomic absorption spectrometry or hydride generation atomic fluorescence spectrometry, for the determination of arsenic and selenium
19、in solid mineral fuels.NOTE The method is also applicable to the determination of the analytes by hydride generation inductively coupled plasma atomic emission spectrometry.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content const
20、itutes requirements 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 687, Solid mineral fuels Coke Determination of moisture in the general analysis test sampleISO 1170
21、, Coal and coke Calculation of analyses to different basesISO 3696, Water for analytical laboratory use Specification 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
22、and lignites Principles of sampling Part 2: Sample preparation for determination of moisture content and for general analysisISO 11722, Solid mineral fuels Hard coal Determination of moisture in the general analysis test sample by drying in nitrogenISO 13909-4, Hard coal and coke Mechanical sampling
23、 Part 4: Coal Preparation of test samplesISO 13909-6, Hard coal and coke Mechanical sampling Part 6: Coke 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 a
24、ddresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp4 PrincipleA known mass of the sample is ignited in intimate contact with Eschkas mixture in an oxidizing atmosphere at 800 C to remove the organic matter. The residue
25、 is then extracted with hydrochloric acid and the analytes determined by hydride generation atomic absorption spectrometry or hydride generation atomic fluorescence spectrometry. ISO 2016 All rights reserved 1BS ISO 11723:2016ISO 11723:2016(E)5 ReagentsWARNING Care must be exercised when handling re
26、agents, many of which are toxic and corrosive.During the analysis, unless otherwise stated, use only reagents of recognized analytical reagent grade and water conforming to Grade 1 of ISO 3696.5.1 Eschkas mixture, composed of two parts by mass of light magnesium oxide and one part by mass of anhydro
27、us sodium carbonate.5.2 Hydrochloric acid (201,19 g/ml).5.3 Nitric acid (201,42 g/ml).5.4 Potassium iodide solution, 500 g/l. Dissolve 50 g of analytical reagent (AR) grade KI in distilled water and adjust the volume to 100 ml (for determination of As).5.5 Sodium borohydride solution. Weigh 1,50 g o
28、f sodium borohydride (NaBH4) and 0,4 g of sodium hydroxide (NaOH) into a plastic bottle of 125 ml capacity and add 100 ml of distilled water. Prepare freshly on the day of use. Alternatively, commercially available pressed pellets of sodium borohydride may be used.5.6 Arsenic stock solution (100 mg/
29、l). Dissolve 0,132 0 g 0,000 5 g of arsenic trioxide (As2O3of 99,9 % purity, dried at 110 C for 1 h) in 25 ml of 20 % KOH solution. Add approximately 50 ml of water and 20 ml of hydrochloric acid (5.2). Adjust the volume with water to 1 litre in a volumetric flask. Alternatively, dissolve 0,416 5 g
30、0,000 5 g of sodium arsenate (Na2HAsO4.7H2O) in approximately 100 ml of water. Add 10 ml of hydrochloric acid (5.2) and adjust the volume with water to 1 l in a volumetric flask.NOTE A commercially available certified stock solution may be used as an alternative.5.7 Dilute arsenic stock solution (1
31、mg/l). Transfer 5 ml of arsenic stock solution to a 500 ml volumetric flask. Add approximately 100 ml of water and 5 ml of hydrochloric acid (5.2). Adjust to volume with water.5.8 Arsenic working standard (50 g/l). Transfer 5 ml of dilute arsenic stock solution (5.7) to a 100 ml volumetric flask. Ad
32、d approximately 20 ml of water and of 1 ml hydrochloric acid (5.2). Adjust to volume with water. Prepare freshly on the day of measurement.5.9 Selenium stock solution (100 mg/l). Dissolve 0,100 0 0,000 5 g of elemental selenium (of 99,9 % purity) in a minimum of nitric acid in a beaker. Evaporate to
33、 dryness. Add 2 ml of water and evaporate to dryness; repeat this procedure twice. Add 10 ml of water to the residue and 10 ml of hydrochloric acid (5.2). Dissolve the residue by heating. Allow the solution to cool and adjust the volume with water to 1 l in a volumetric flask. Alternatively, dissolv
34、e 0,467 4 g 0,000 5 g of sodium selenate (Na2SeO4.10H2O) in approximately 100 ml of water. Add 10 ml of hydrochloric acid (5.2) and adjust the volume with water to 1 l in a volumetric flask.NOTE A commercially available certified stock solution may be used as an alternative.5.10 Dilute selenium stoc
35、k solution (1 mg/l). Transfer 5 ml of selenium stock solution (5.9) to a 500 ml volumetric flask. Add approximately 100 ml of water and 5 ml of hydrochloric acid (5.2). Adjust to volume with water.2 ISO 2016 All rights reservedBS ISO 11723:2016ISO 11723:2016(E)5.11 Selenium working standard (50 g/l)
36、. Transfer 5 ml of dilute selenium stock solution (5.10) to a 100 ml volumetric flask. Add approximately 20 ml of water and 1 ml of hydrochloric acid (5.2). Adjust to volume with water. Prepare freshly on the day of measurement.6 Apparatus6.1 Balance, capable of weighing to the nearest 0,1 mg.6.2 Cr
37、ucible, a shallow silica crucible of capacity approximately 25 ml.6.3 Silica plate, 6 mm thick, having an easy sliding fit in the muffle furnace.6.4 Muffle furnace, capable of obtaining 800 C over 2 h from ambient temperature.6.5 Plastic bottle, wide necked, of capacity 60 ml (autoclavable) with scr
38、ew-threaded lid.6.6 Atomic absorption spectrometer or atomic fluorescence spectrometer, equipped with a hydride generation apparatus.To minimize potential contamination, clean all laboratory ware with dilute HCl (1 + 10).7 Preparation of the test sampleThe test sample is the general analysis sample,
39、 prepared in accordance with ISO 5069-2, ISO 13909-4 or ISO 13909-6, as appropriate. Expose the sample in a thin layer for the minimum time required for the moisture content to reach approximate equilibrium with the laboratory atmosphere.Before commencing the determination, mix the equilibrated samp
40、le thoroughly.If the results are to be calculated to other than on an as analysed basis i.e. air-dried (see Clause 10), concurrently determine the moisture content using a further portion of the test sample by the method described in ISO 5068, ISO 11722 or ISO 687, as appropriate.8 Procedure8.1 Blan
41、k determinationA blank determination shall be carried out at the same time and under the same conditions as the actual determination, but omitting the sample.8.2 Preparation of test solutionThe procedure, carried out in duplicate, shall be as follows.Weigh, to the nearest 0,000 1 g, a test portion o
42、f approximately 0,5 g and mix intimately with 0,8 g of Eschkas mixture (5.1) in the crucible (6.2). Level the contents of the crucible and cover with 0,2 g of Eschkas mixture.Place the charged crucible on the cold silica plate (6.3). Insert both into the cold muffle furnace (6.4) and heat at a unifo
43、rm rate to 800 C for 2 h. Maintain at this temperature for a further 2 h.Remove the silica plate and crucible from the furnace and allow to cool.Transfer the contents of the crucible to the tared plastic bottle (6.5). Wash the residue into the bottle with 5 ml to 10 ml of water (alternatively into a
44、 100 ml beaker). ISO 2016 All rights reserved 3BS ISO 11723:2016ISO 11723:2016(E)Add 10 ml of hydrochloric acid (5.2) to the crucible and gently warm on a hotplate. Transfer to the bottle (or beaker). Wash the crucible with a further 5 ml of water and transfer the washings to the bottle (alternative
45、ly to a beaker). Shake gently to allow the evolution of any carbon dioxide produced.WARNING Hydrochloric acid must be added carefully as the reaction with Eschkas mixture is exothermic and releases carbon dioxide.Allow the bottle to cool and adjust the mass of solution to 50,0 g with water (alternat
46、ively, transfer the solution from the beaker to a 50 ml volumetric flask and make up to volume).8.3 Preparation of calibration standardsAdd 1 g of Eschkas mixture (5.1) to four tared plastic bottles (6.5) (alternatively to beakers). Add approximately 10 ml of water and 20 ml of hydrochloric acid (5.
47、2) to dissolve the Eschkas mixture.Allow the solutions to cool. Adjust one solution to 50,0 g (alternatively, transfer solution to 50 ml volumetric flasks and adjust one to volume with water). This is the calibration blank. To the other bottles (or flasks), add respectively, 1,00 ml, 2,00 ml and 3,0
48、0 ml 0,02 ml of the appropriate working standard (5.8) or (5.11). Adjust the mass of solution to 50,0 g (alternatively 50,0 ml). These calibration standards are 1 g/kg, 2 g/kg and 3 g/kg of solution (or g/l).8.4 Preparation for measurement8.4.1 GeneralSolutions are prepared as in 8.4.2 and 8.4.3.8.4
49、.2 ArsenicPipette 10 ml of each calibration standard and test solution, including blanks, of solution into separate plastic vials of capacity approximately 30 ml.Add 5 ml of hydrochloric acid (5.2) to each vial.Add 0,5 ml of potassium iodide solution (5.4) to each vial and let stand for 20 min.8.4.3 SeleniumPipette 10 ml of each calibration standard and test solution, including blanks, into tall beakers or test tubes of capacity 25 ml to 50 ml. Add 5 ml of HCl. Heat
