BS ISO 10775-2013 Paper board and pulps Determination of cadmium content Atomic absorption spectrometric method《纸 纸板和纸浆 镉含量的测定 原子吸收光谱法》.pdf

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1、BSI Standards PublicationBS ISO 10775:2013Paper, board and pulps Determination of cadmiumcontent Atomic absorptionspectrometric methodBS ISO 10775:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 10775:2013. Itsupersedes BS ISO 10775:1995 which is withdrawn

2、.The UK participation in its preparation was entrusted to TechnicalCommittee PAI/11, Methods of test for paper, board and pulps.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of

3、 a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 81226 2ICS 85.040; 85.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published und

4、er the authority of theStandards Policy and Strategy Committee on 31 August 2013.Amendments issued since publicationDate Text affectedBS ISO 10775:2013 ISO 2013Paper, board and pulps Determination of cadmium content Atomic absorption spectrometric methodPapier, carton et ptes Dtermination de la tene

5、ur en cadmium Mthode par spectromtrie dabsorption atomiqueINTERNATIONAL STANDARDISO10775Second edition2013-08-01Reference numberISO 10775:2013(E)BS ISO 10775:2013ISO 10775:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All rights reserved. Unless otherwise specified, no p

6、art 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 permission. Permission can be requested from either ISO at the address below or ISOs member

7、body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 10775:2013ISO 10775:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 N

8、ormative references 13 Principle 14 Reagents 15 Apparatus . 26 Sampling and sample preparation 37 Wet combustion . 37.1 Test sample preparation . 37.2 Combustion procedure 37.3 Dilution 38 Blank . 49 Preparation of calibration solutions . 410 Determination of cadmium . 411 Calculation 512 Test repor

9、t . 5Annex A (informative) Precision . 6BS ISO 10775:2013ISO 10775:2013(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 tec

10、hnical 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 take part in the work. ISO collaborates closel

11、y with the 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 nee

12、ded for the 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. www.iso.org/directivesAttention is drawn to the possibility that some of the elements of this document may be the subject of patent rights

13、. ISO 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. www.iso.org/patentsAny trade name used in this documen

14、t is information given for the convenience of users and does not constitute an endorsement.The committee responsible for this document is ISO/TC 6, Paper, board and pulps.This second edition cancels and replaces the first edition (ISO 10775:1995), of which it constitutes a minor revision.iv ISO 2013

15、 All rights reservedBS ISO 10775:2013INTERNATIONAL STANDARD ISO 10775:2013(E)Paper, board and pulps Determination of cadmium content Atomic absorption spectrometric method1 ScopeThis International Standard specifies a method for the determination of traces of cadmium in all types of paper, board and

16、 pulp, including products containing recycled fibre, that can be wet-combusted in nitric acid as specified in this International Standard.The lower limit of the determination depends on the equipment used and is normally about 10 g/kg. Cadmium present in pigments and fillers that do not dissolve in

17、nitric acid under the conditions of this test may not be determined quantitatively.NOTE It has been claimed that the dissolution of cadmium from pigments other than calcium carbonate is incomplete by a few percent.2 Normative referencesThe following documents, in whole or in part, are normatively re

18、ferenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 186, Paper and board Sampling to determine average qualityISO 287, P

19、aper and board Determination of moisture content of a lot Oven-drying methodISO 638, Paper, board and pulps Determination of dry matter content Oven-drying methodISO 7213, Pulps Sampling for testing3 PrincipleThe sample is treated with nitric acid in a closed vessel. The resulting solution is dilute

20、d and cadmium content determined by atomic absorption spectrometry using the graphite furnace technique.Wet combustion may be done either in an autoclave or microwave oven.4 ReagentsAll reagents shall be of the highest possible purity. The quality normally designated “pro analysi” or “analytical rea

21、gent (AR)” is often not sufficiently pure. Use only freshly distilled and deionized water or water of equivalent purity.NOTE Commercially available solutions may also be used.4.1 Concentrated nitric acid, c(HNO3) = 15 mol/lUse a quality specially made for use in the determination of trace metals.4.2

22、 Dilute nitric acid, c(HNO3) = 0,15 mol/lDilute with water 10 ml of concentrated nitric acid (4.1) to one litre. ISO 2013 All rights reserved 1BS ISO 10775:2013ISO 10775:2013(E)4.3 Cadmium nitrate standard solution, p(Cd) = (1,000 0,002) g/l, made, for example, by dissolving 2,774 g of cadmium nitra

23、te tetrahydrate, Cd(NO3)2 4H2O, per litre of nitric acid, c(HNO3) = 0,5 mol/l.4.4 Cadmium stock calibration solution, (Cd) = 1,00 mg/lpUsing a precision pipette dilute 1,00 ml of the cadmium standard solution (4.3) to 1 000 ml with dilute nitric acid (4.2) in a volumetric flask. Mix by shaking the f

24、lask.The solution has a shelf life of several months if stored in a polyethylene bottle.4.5 Matrix modifier solutionSeveral matrix modifier solutions are recommended in the literature. The three solutions given in 4.5.1 to 4.5.3 are in common use. The choice among them depends on their performance i

25、n each particular laboratory, which is evaluated by running a blank.4.5.1 Palladium nitrate solutionDissolve 2,0 g of Pd(NO3)2in 10 ml of nitric acid (4.1) and dilute with water to 500 ml in a volumetric flask. (Alternatively, the equivalent amount of palladium metal, i.e. 0,924 g, is dissolved in n

26、itric acid.) Prepare a working solution by diluting 5 ml of this stock solution with water to 100 ml.or4.5.2 Ammonium dihydrogenphosphate solutionDissolve 2 g of NH4H2PO4in water and dilute to 100 ml.or4.5.3 Magnesium nitrate solutionDissolve 0,5 g of Mg(NO3)2in water and dilute to 100 ml.5 Apparatu

27、sOrdinary laboratory equipment and the following.5.1 Apparatus for wet combustion, either:5.1.1 Autoclave, with an inner vessel of polytetrafluoroethylene (PTFE), capacity 250 ml, provided with a lid of PTFE, and a heating block that can maintain the autoclave at a temperature of 160 5 C.The block s

28、hall be provided with an extra safety switch that prevents overheating.NOTE 1 The PTFE vessels can be protected from corrosion from the outside by applying a film of silicone grease on all outside surfaces. The film is removed and renewed after each heating period. Vessels treated in this manner sho

29、uld not be used when silica has to be determined.NOTE 2 The use of an oven instead of the heating block is not recommended because of the hazard involved in removing the hot autoclaves from the oven at the end of the heating period.or5.1.2 Laboratory microwave oven, with programming facilities, spec

30、ially designed for wet combustion, with digestion vessels of PTFE, capacity at least 120 ml, having safety valves to release pressures over 830 kPa.2 ISO 2013 All rights reservedBS ISO 10775:2013ISO 10775:2013(E)5.2 Atomic absorption spectrometer, equipped for the graphite furnace technique and with

31、 a so-called “Lvov” platform, and with a lamp for the determination of cadmium.Preferably, the instrument should have background correction.6 Sampling and sample preparationEnsure that the sample is representative of the lot to be tested. If applicable, follow the instructions given in ISO 186 or in

32、 ISO 7213.In order to avoid contamination, keep the samples wrapped in aluminium foil until required.Tear from the sample enough pieces, about 10 mm x 10 mm in size, to provide the amount required, taking an approximately equal amount from each sample. Do not use a knife or any other metal tool. (To

33、ols of plastics or ceramics may be used.) Split samples of pulp sheets or board to reduce their thickness.Keep the sample near the balance for moisture equilibration for at least 20 min. Withdraw a specimen for the determination of dry matter content in accordance with ISO 287 or ISO 638, as applica

34、ble.7 Wet combustionCarry out wet combustion in duplicate; also run a blank (see Clause 8).7.1 Test sample preparationWeigh a test portion of 1 g to the nearest 1,0 mg and transfer it to the appropriate PTFE vessel (5.1). Add 10 ml of the concentrated nitric acid (4.1). Close the vessel with its lid

35、 and place it in the autoclave (5.1.1) or in the microwave oven (5.1.2), as applicable.7.2 Combustion procedure7.2.1 Autoclave procedureIf an autoclave is used, close the autoclave as instructed by the manufacturer and place it in the heating block (5.1.1). Heat it at 160 5 C for 16 1 h. Allow the h

36、eating block and the autoclave to cool and, with caution, open the autoclave in a hood. Proceed to 7.3.7.2.2 Microwave oven procedureIf a microwave oven is used, the test portion size shall be adjusted to the capacity of the digestion vessel. If this is 120 ml, the maximum test portion mass shall be

37、 0,3 g. If more test portion is taken, the safety valve of the digestion vessel will activate.Set the power regulator to the predetermined value and heat the closed digestion vessel (5.1.2), with its contents for 10 20 min typically, 30 min maximum, depending on the microwave power. Allow the vessel

38、 to cool and, with caution, open it in a hood.The correct setting of the power regulator shall be determined separately for each oven. A typical setting is 40 % of the maximum power. Also see 5.1.2.7.3 DilutionAllow nitrous fumes to escape from the wet combustion vessel and dilute the remaining solu

39、tion to a known volume with water. The dilution volume depends on the equipment used, and should be kept as small as possible.The dilution can be made in a disposable graduated plastic vessel. Volumetric flasks thoroughly cleaned, may also be used. ISO 2013 All rights reserved 3BS ISO 10775:2013ISO

40、10775:2013(E)Alternatively, dilute the remaining solution directly in the digestion vessel by adding from a graduated pipette the required volume of water. In this case, the volume of the residual nitric acid shall be determined in a separate experiment.Allow any suspended solids to settle.8 BlankFo

41、llow the instructions in Clause 7, but use no sample.9 Preparation of calibration solutionsPrepare the calibration solution daily by diluting the stock calibration solution (4.4) with dilute nitric acid (4.2). The cadmium content selected for the final calibration solution depends on the particular

42、instrument to be used. In general, a calibration solution having a cadmium mass concentration of 10 g/l (0,01 g/ml) is appropriate.10 Determination of cadmium10.1 The procedure for the spectrometric determination of the cadmium content of the test solutions depends on the design of the atomic absorp

43、tion spectrometer (5.2) and of the graphite furnace. The manufacturers instructions should be followed when operating the instrument.In general, the technique with standard additions (see 10.2) should be used. In practice, the normal calibration procedure, based on a calibration curve, may be used,

44、provided that there is no interference from the matrix. This must be verified by analysing suitable reference materials.Before using the normal calibration procedure, check that any matrix effects are under control by running the same type of sample by the standard addition technique. In particular,

45、 differences in acid concentration between standards and sample solutions affect the results. The acid concentration of the standard solutions should be adjusted to that of the sample solutions by replacing part of the diluent (4.2) by concentrated nitric acid (4.1).10.2 For the technique with stand

46、ard additions, the following instructions are given as a guide.Prepare the solutions for measurement directly in the graphite tube by means of a sampler. Typical solutions and volumes are given in Table 1 as an example.Table 1 Example of the technique with standard additionsSolution to be measured C

47、alibration solution aSample aBlank aMatrix modifier solu-tion a(4.5)Blank 0 0 20 5Solution 1 2 10 8 5Solution 2 4 10 6 5Solution 3 6 10 4 5Sample 0 10 10 5aVolumes in microlitres.10.3 Prepare a plot on graph paper or using software such as an Excel spreadsheet. Use as y-values the readings from the

48、spectrometer (peak area or absorbance values, corrected for the value obtained for the 4 ISO 2013 All rights reservedBS ISO 10775:2013ISO 10775:2013(E)blank) and as the x-values the amounts, in units of mass, of cadmium added with the solutions 1, 2 and 3. The value obtained for the sample solution

49、is plotted on the y-axis.Draw a straight line through the four plotted points. This line intersects the x-axis on its negative side. The point of intersection represents the cadmium content in the sample solution.NOTE If the four points do not fall on a straight line, it is acceptable to use a line of best fit. If it is obvious from the diagram that the precision of the result is poor, the analysis should be repeated. If the points still are widely scattered, there is some serious error or the level of the res