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1、BRITISH STANDARD BS ISO 779:2001 Paper, board and pulps Determination of iron ICS 85.060; 85.040; 71.040.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 779:200
2、1 This British Standard, having been prepared under the direction of the Sector Committee for Materials and Chemicals, was published under the authority of the Standards Committee and comes into effect on 15 September 2001 BSI 07-2001 ISBN 0 580 38290 7 National foreword This British Standard reprod
3、uces verbatim ISO 779:2001 and implements it as the UK national standard. It supersedes BS 4897-3:1983 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PAI/11, Methods of test for paper, board and pulps, which has the responsibility to: A list of organ
4、izations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standar
5、ds Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard
6、 does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European d
7、evelopments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 6, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last is
8、sued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 779:2001(E) INTERNATIONAL STANDARD ISO 779 Second edition 2001-06-01 Paper, board and pulp Determination of
9、iron Papier, carton et pte Dtermination de la teneur en fer Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii ISO 779:2001(E) vi Inrtitcudono Thsi retnItannoial Stdnarad croresnopsd ot ISO 7771dna OSI 7782?ni roder to mkae it sopsible to re
10、pform eht filan msaerumetne fo lla trhee elmestne on teh same sotulino. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 779:2001(E) iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of nation
11、al 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 established has the right to be represented on that committee. Internatio
12、nal 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 standardization. International Standards are drafted in accordance with the rule
13、s given in the ISO/IEC Directives, Part 3. 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. Attention is drawn to the poss
14、ibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 779 was prepared by Technical Committee ISO/TC 6, Paper, board and pulps. This second edit
15、ion cancels and replaces the first edition (ISO 779:1982), of which it constitutes a technical revision. The previous edition of this International Standard included the photometric procedure as well as the procedure based on atomic absorption spectroscopy. The photometric procedure has been deleted
16、, as it is now seldom used. The scope has been enlarged to include paper and board in addition to pulp. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 779:2001(E) iv Introduction This International Standard corresponds to ISO 7771and IS
17、O 7782?in order to make it possible to perform the final measurement of all three elements on the same solution. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARDISO 779:2001(E) 1 Paper, board and pulp Determination of i
18、ron WARNING The method specified in this International Standard involves the use of some hazardous chemicals and of gases that can form explosive mixtures with air. Care must be taken to ensure that the relevant precautions are observed. 1Scope This International Standard specifies the procedure for
19、 the determination of iron by atomic absorption spectrometry or by plasma emission spectrometry. It is applicable to all kinds of paper, board and pulp. It specifies a method to determine the acid-soluble part of the incineration residue, i.e. that part of the ignition residue obtained after inciner
20、ation which is soluble in hydrochloric acid. If the residue is completely soluble, the result obtained by the procedure specified in this International Standard is taken as the total amount of iron in the sample. 2Normative references The following normative documents contain provisions which, throu
21、gh reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility
22、of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 186, Paper and board Sampling to determ
23、ine average quality. ISO 287, Paper and board Determination of moisture content Oven-drying method. ISO 638, Pulps Determination of dry matter content. ISO 1762, Paper, board and pulps Determination of residue (ash) on ignition at 525 C. ISO 7213, Pulps Sampling for testing. 3Term and definition For
24、 the purposes of this International Standard, the following term and definition applies. 3.1 mass fraction of iron amount of the element iron in the solution obtained after incineration of the specimen at 525 C and treating the residue with 6 mol/l hydrochloric acid as specified in this Internationa
25、l Standard. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 779:2001(E) 2 4Principle A test portion is incinerated at 525 C and the residue is treated with 6 mol/l hydrochloric acid. The test solution is aspirated into an acetylene/dinit
26、rogen monoxide or acetylene/air flame and the mass fraction of iron is determined by one of the following procedures: measurement of the absorption of the 248,3 nm line emitted by an iron hollow-cathode lamp; or measurement of the absorption of the 248,3 nm line emitted by plasma emission spectromet
27、ry. 5Reagents and materials Use only chemicals of recognized analytical grade and only distilled or deionized water. 5.1Hydrochloric acid, about 6 mol/l. Dilute 500 ml of hydrochloric acid (density 1,19 g/ml) in 500 ml of water. 5.2Iron stock solution, 100 mg/l of Fe. Dissolve 100 mg of pure iron wi
28、re in the smallest quantity possible of hydrochloric acid (density 1,19 g/ml) in a 1 000 ml volumetric flask. Dilute with water to the mark and mix. 1 ml of this stock solution contains 0,10 mg of Fe. 5.3Iron standard solution, 10 mg/l of Fe. Transfer 100 ml of the iron stock solution (5.2) to a 1 0
29、00 ml volumetric flask and add 200 ml of hydrochloric acid (5.1). Dilute with water to the mark and mix. 1 ml of this standard solution contains 0,01 mg of Fe. The solution is not stable. Commercially available, certified standard iron solutions may be used. 5.4Acetylene gas and/or dinitrogen monoxi
30、de gas, of a grade suitable for atomic absorption spectrometry. WARNING Acetylene gas forms explosive mixtures with air. 5.5Appropriate gas for the plasma spectrometer (6.4). Argon is usually recommended as a carrier gas. 6Apparatus and equipment Ordinary laboratory equipment. Clean all equipment in
31、 0,1 mol/l hydrochloric acid. 6.1Filter paper, ash free, particle retention 20 ?m to 25 ?m. 6.2Dishes, of platinum or quartz. 6.3Atomic absorption spectrometer, with a burner for dinitrogen monoxide/acetylene or air/acetylene and with a hollow-cathode lamp for iron. NOTEA multi-element lamp may be u
32、sed. 6.4Inductively coupled plasma spectrometer. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 779:2001(E) 3 7Sampling and preparation of sample If the analysis is being made to evaluate a lot of paper, board or pulp, the sample shall
33、be selected in accordance with ISO 186 or ISO 7213, as relevant. If the analysis is made on another type of sample, report the source of the sample, and, if possible, the sampling procedure. Select the specimens so that they are representative of the sample received. A sufficient amount of sample sh
34、all be collected to allow for at least duplicate determinations. Avoid cut edges, punched holes and other parts where metallic contamination may have occurred. Prepare a test specimen by tearing at least 30 g of small pieces from various parts of the sample. This amount is sufficient for the duplica
35、te determinations as prescribed in clause 8. 8Procedure 8.1Incineration and dissolution of the residue Carry out the procedure in duplicate. Air-dry the specimen in the laboratory atmosphere until it reaches moisture equilibrium. Determine the moisture content on a separate air-dried portion as spec
36、ified in ISO 287 or ISO 638, as relevant. Weigh this portion at the same time as the test portion used for incineration. Carry out ashing of the test portion as described in ISO 1762. A portion of 2 g to 5 g is usually sufficient. Carry out the dissolution of the ash under a fume hood. To avoid spla
37、ttering, carefully moisten the ash with water and add 5 ml of hydrochloric acid (5.1) to the dish. Evaporate to dryness on a boiling-water bath or equivalent device. Repeat this procedure. For samples with a high carbonate content, more than 10 ml of acid (2?5 ml) may be needed, for example 20 ml (2
38、?10 ml). Add 2,5 ml of the hydrochloric acid (5.1) in order to dissolve the residue. If necessary, heat the dish covered by a watch glass for a few minutes. Using the filter paper (6.1), filter the contents of the dish into a 25 ml volumetric flask. To ensure that the transfer is complete, add anoth
39、er portion of 2,5 ml of acid to the dish and heat again. Filter this last portion of acid into the main portion in the volumetric flask with the aid of some water. Fill up to the mark and mix. This is the test solution. 8.2Blank Run a blank with the same quantity of each of the chemicals as those ad
40、ded to the incineration residue but without any residue. 9Preparation of calibration solutions It is important that the acid concentration is the same in the calibration and in the test solution since the acid concentration influences the signal. From the iron standard solution (5.3), prepare at lea
41、st three calibration solutions, and in addition one zero solution, for the construction of the calibration graph. (The zero solution is similar to the calibration solutions, but contains no added iron. Do not confuse it with the blank.) NOTENot more than two calibration solutions are needed for plas
42、ma emission spectrometry Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 779:2001(E) 4 10 Determination Carry out the spectrometric measurement of the calibration solutions, including the zero solution, the test solution and the blank so
43、lution. Operate the instrument as instructed by the manufacturer. The solutions may contain lanthanum or caesium, if the same solutions are used for the determination of calcium. These salts do not interfere with the determination of iron, but the same amounts of salts shall be added to the calibrat
44、ion solutions. If any value obtained exceeds the range covered by the calibration solutions, the measurement shall be repeated with a more dilute test solution. Add acid, caesium solution or lanthanum solution as required. Most instruments have a system for automatic evaluation of results. If the in
45、strument has no automatic evaluation system, construct the calibration graph by plotting the absorbance, corrected for the blank, against the concentration of iron in milligrams per litre.Then read the iron concentration in the test solution from the calibration graph. 11 Calculation Calculate the m
46、ass fraction of iron from the expression Fe Fe fV m ? ? ? ? where ?Feis the mass fraction of iron in the sample, in milligrams per kilogram; ?Feis the iron concentration in the test solution, as obtained from the calibration plot corrected for the blank, in milligrams per litre; Vis the volume, in m
47、illilitres, of the original test solution (standard volume = 25 ml); mis the mass of sample taken, oven-dry basis, in grams; fis the dilution factor; f = 1, unless the original test solution has been diluted. Calculate the mean with two significant figures. 12 Precision 12.1 General A study1)gave th
48、e following results. 12.2 Repeatability A sample of uncoated paperboard was analysed in one laboratory nine times. The mean found was 13 mg/kg, and the coefficient of variation (CV) was 8 %. NOTEAs the study comprises only one sample and one laboratory, the result is only a rough estimation of the r
49、epeatability. 1)Study made by SCAN-test in 1996. Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 08:27:46 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 779:2001(E) 5 12.3 Reproducibility Four samples were analysed in eight laboratories. The results in Table 1 were obtained for the mean and the coefficient of variation (CV). Table 1 MeanCV Sample type mg/kg% Bleached pulp3,645 Coated paperboard43019 Uncoated paperboard1328 Copy paper1804 NOTEThehighCV-valuesarepossiblyduetoanuneven distribution of iron in the sample. 13 Test report The test