BS ISO 17058-2004 Steel and iron - Determination of arsenic content - Spectrophotometric method《钢铁 砷含量的测定 分光光度法》.pdf

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1、BRITISH STANDARD BS ISO 17058:2004 Steel and iron Determination of arsenic content Spectrophotometric method ICS 77.080.01 BS ISO 17058:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2004 BSI 30 November 2004 ISBN 0 580 4492

2、3 8 National foreword This British Standard reproduces verbatim ISO 17058:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee ISE/18, Sampling and analysis of iron and steel, which has the responsibility to: A list of organ

3、izations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Inde

4、x”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself conf

5、er 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 developments and promulga

6、te 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 11 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication A

7、md. No. Date Comments Reference number ISO 17058:2004(E)NINRETOITALAN ADNATSDR OSI 18507 tide tsriFino -400210-20 Steel and iron Determination of arsenic content Spectrophotometric method Aciers et fontes Dosage de larsenic Mthode spectrophotomtrique Referecne unbmer OSI 85071002:)E(4INTERNATIONAL S

8、TANDARD ISO 17058 First edition 2004-02-01 na leetSori dn reteDanimoitn fo cinesra tnoctne pS ceportohotcirtem temdoh cAreis te tnofse D soega l edrascine Mtdohe sceprttohpomortiqeu BSISO17058:2004 ii BSISO17058:2004 iiiContents Page Foreword iv 1 Scope 1 2 Normative references . 1 3 Principle . 1 4

9、 Reagents 2 5 Apparatus. 3 6 Sampling 3 7 Procedure. 4 7.1 Test portion sampling. 4 7.2 Blank test . 5 7.3 Determination 5 7.4 Establishment of the calibration graph 6 8 Expression of results 7 8.1 Method of calculation . 7 8.2 Precision 7 9 Test report 8 Annex A (informative) Additional information

10、 on international cooperative tests 9 Annex B (informative) Graphical representation of precision data. 10 Bibliography . 11 BSISO17058:2004iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of pre

11、paring 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. International organizations, governmental and non-governmental, in

12、 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 rules given in the ISO/IEC Directives, Part 2. The main task

13、 of technical committees is to prepare International Standards. 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

14、 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. ISO 17058 was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of determination of

15、 chemical composition. BSISO17058:2004INTENRATIONAL TSANDADR IS:85071 O4002(E)1Steel and iron Determination of arsenic content Spectrophotometric method 1 Scope This International Standard specifies a method for the determination of the arsenic content in steel and iron using a spectrophotometric me

16、thod after distillation. The method is applicable to an arsenic content between 0,000 5 % (mass fraction) and 0,10 % (mass fraction). 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies

17、. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 385-1:1984, Laboratory glassware Burettes Part 1:General requirements ISO 648:1977, Laboratory glassware One-mark pipettes ISO 1042:1998, Laboratory glassware One-mark volumetric flasks IS

18、O 3696:1987, Water for analytical laboratory use Specification and test methods ISO 14284:1996, Steel and iron Sampling and preparation of samples for the determination of chemical composition 3 Principle Dissolution of a test portion in a hydrochloric acid and nitric acid mixture. Prolonged heating

19、 with sulfuric acid until white fumes are given off. Reduction of arsenic in the presence of hydrazine sulfate and potassium bromide, then separation by distillation as the trivalent chloride, absorbed in the nitric acid solution, in which the As(III) is oxidized back to the pentavalent state As(V).

20、 Formation of the molybdenum blue complex between ammonium molybdate and arsenic which is reduced by hydrazine sulfate. Spectrophotometric measurement at a wavelength of approximately 840 nm. BSISO17058:20042 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized an

21、alytical grade and only grade 3 water specified in ISO 3696:1987. 4.1 Hydrochloric acid, about 1,19 g/ml 4.2 Nitric acid, about 1,40 g/ml 4.3 Nitric acid, about 1,40 g/ml, diluted 3 + 1 4.4 Acid mixture Add one volume of nitric acid (4.2) to four volumes of hydrochloric acid (4.1). 4.5 Sulfuric acid

22、, about 1,84 g/ml 4.6 Sulfuric acid, about 1,84 g/ml, diluted 1 + 1 While cooling under water and swirling, add, in small portions, a volume of sulfuric acid (4.5) to an equal volume of water. 4.7 Sulfuric acid, about 1,84 g/ml, diluted 1 + 6 While cooling under water and swirling, add, in small por

23、tions, a volume of sulfuric acid (4.5) to six volumes of water. 4.8 Mixture of reducant powder Weigh, in proportion, 2,5 g of hydrazine sulfate and 10,0 g of potassium bromide, transfer to a mortar and, using a pestle, grind finely and mix well for use. 4.9 Ammonium molybdate, (NH 4 ) 6 Mo 7 O 24 .

24、4H 2 O, 10 g/l 4.10 Hydrazine sulphate, N 2 H 6 SO 40,6 g/l 4.11 Arsenic, standard solution 4.11.1 Stock solution, corresponding to 0,20 g of arsenic per litre Weigh, to the nearest 0,000 1 g, 0,132 0 g of arsenic trioxide (As 2 O 3 ). Place in a 100 ml beaker, carefully add 10 ml of nitric acid (4.

25、2), cover with a watch glass, heat gently until dissolution is complete. Add 2 ml of sulphuric acid (4.6), heat cautiously to expel oxides of nitrogen and then evaporate to dense, white fumes. Remove the beaker from the hot plate, cool somewhat, and wash down the cover and sides of the beaker with a

26、 little water. Again evaporate to copious white fumes. Remove, cool and add about 10 ml of water, warm gently until salts are dissolved and the solution becomes clear. Cool to room temperature, transfer the solution quantitatively to a 500 ml one-mark volumetric flask. Dilute to the mark with water

27、and mix. 1 ml of this stock solution contains 0,2 mg of arsenic. BSISO17058:2004 34.11.2 Standard solution A, corresponding to 0,01 g of arsenic per litre Transfer 25,0 ml of the stock solution (4.11.1) to a 500 ml one-mark volumetric flask. Dilute to the mark with water and mix. Prepare this soluti

28、on immediately before use. 1 ml of this standard solution contains 10 g of arsenic. 4.11.3 Standard solution B, corresponding to 0,002 g of arsenic per litre. Transfer 50,0 ml of the standard solution (4.11.2) to a 250 ml one-mark volumetric flask. Dilute to the mark with water and mix. Prepare this

29、 solution immediately before use. 1 ml of this standard solution contains 2 g of arsenic. 4.12 Potassium Bromide 5 Apparatus All volumetric glassware shall be class A, in accordance with ISO 385-1:1984, ISO 648:1977 and ISO 1042:1998. Ordinary laboratory apparatus and the following shall be used. 5.

30、1 Spectrophotometer, suitable for measuring the absorbance of the solution at a wavelength of 840 nm with 40 mm (or 10 mm) optical cells 5.2 Distillation apparatus, see attached diagram (Figure 1) 6 Sampling Carry out sampling in accordance with ISO 14284 or appropriate national standards for steel.

31、 BSISO17058:20044 Dimensions in millimetres Key 1 conical flask (distillation flask), 250 ml 2 thermometer 3 thermometer well 4 receiving beaker, 100 ml 5 cooling beaker, 1 000 ml 6 valve Figure 1 Distillation apparatus for arsenic determination 7 Procedure 7.1 Test portion sampling Weigh, to the ne

32、arest 0,1 mg, a test portion of the sample in accordance with Table 1. Table 1 Test portion sampling Expected arsenic content % (mass fraction) Test portion g 0,000 5 to 0,001 1,0 0,001 to 0,006 0,50 0,006 to 0,100 0,10 BSISO17058:2004 57.2 Blank test In parallel with the determination and the same

33、procedure, carry out a blank test using the same quantities of all the reagents. 7.3 Determination 7.3.1 Preparation of the test solution Place the test portion (see 7.1) in a 150 ml beaker. Add 10 ml to 20 ml of the acid mixture (4.4). Cover the beaker with a watch-glass and heat gently to complete

34、 dissolution. Cool the solution, remove the watch-glass and add 20 ml of sulphuric acid (4.6). Replace the watch-glass leaving small opening to allow for the expulsion fumes and evaporate to dense white fumes. 7.3.2 Distillation Transfer the test solution (see 7.3.1) quantitatively to the distillati

35、on flask, rinse down the cover and the sides of the beaker with approximately 10 ml of water. If any undissolved sulfate salts remain, add a small amount of water and warm until the salts are in solution. Cool in water, add 10 ml of hydrochloric acid (4.1), 2,0 g of mixed reductant powder (4.8), and

36、 mix. Add 10 ml of nitric acid (4.3) to the receiving beaker, and place the beaker in the cooling beaker containing cold water. Assemble the apparatus for distillation (5.2). Heat the distillation flask at a low temperature, distil until the temperature rises to 125 C, keeping the entire distillatio

37、n procedure within 6 min to 10 min. Open the valve to avoid the solutions flowing back from the receiving beaker, and remove the distillation flask from the heat source. Rinse down the tip of the outlet with a small amount of water. Collect the washings in the receiving beaker. Add 3,5 ml of sulfuri

38、c acid (4.7) and mix. Replace the watch-glass leaving a small opening to allow for the expulsion of fumes and evaporate to dense white sulfuric acid fumes. During this procedure no bubbles should appear. Remove and cool somewhat, rinse down the cover and the sides of the beaker, and again evaporate

39、to white fumes to expel the oxides of nitrogen. Remove the beaker from the heat source and allow it to cool. Rinse down the cover and transfer the solution quantitatively to a 50 ml one-mark volumetric flask. 7.3.3 Formation of the coloured complex Add 2,5 ml of ammonium molybdate solution (4.9) and

40、 2,5 ml of hydrazine sulfate solution (4.10) to the flask, dilute to the mark with water and mix. Warm the flask in a boiling water bath for 10 min. Remove the flask and cool to room temperature. 7.3.4 Spectrophotometric measurements Carry out spectrophotometric measurements of each solution at a wa

41、velength of about 840 nm after having adjusted the spectrophotometer to zero absorbance by reference to water using 40 mm (or 10 mm) cells. BSISO17058:20046 7.4 Establishment of the calibration graph 7.4.1 Preparation of calibration solution Introduce into a series of 50 ml one-mark flasks the volum

42、es of arsenic standard solution (4.11.2, 4.11.3) as indicated in Table 2 for arsenic content between 0,000 5 % (mass fraction) and 0,030 % (mass fraction) and Table 3 for arsenic content between 0,030 % (mass fraction) and 0,100 % (mass fraction). Add 2,5 ml of sulfuric acid (4.7) to each one-mark f

43、lask. Proceed as described in 7.3.3. 7.4.2 Spectrophotometric measurements Carry out spectrophotometric measurements of the range of calibration solutions at a wavelength of about 840 nm after having adjusted the spectrophotometer to zero absorbance by reference to water using 40 mm (or 10 mm) cells

44、. 7.4.3 Plotting the calibration graph Calculate the difference in absorbance between the solutions and the value obtained for the zero member. Prepare the straight-line calibration graph, which passes through the origin, by plotting the net absorbance reading against micrograms of arsenic. Calibrat

45、ion solution for arsenic content between 0, 000 5 % (mass fraction)and 0, 030 % (mass fraction) which 40 mm cells are used shown in Table 2. Table 2 Calibration solution for arsenic content between 0, 000 5 % (mass fraction) and 0, 030 % (mass fraction) for which 40 mm cells are used Arsenic content

46、 of the test sample % (mass fraction) Volume of arsenic standard solution (4.11.3) ml Corresponding mass of arsenic g Test portion of 0,10 g Test portion of 0,50 g Test portion of 1,00 g 0 a0 0 0 0 2,0 4 0,000 4 4,0 8 0,008 0,001 6 0,000 8 6,0 12 0,012 0,002 4 8,0 16 0,016 0,003 2 10,0 20 0,020 0,00

47、4 15,0 30 0,030 0,006 aZero member. Calibration solution for arsenic content between 0, 030 % (mass fraction) and 0, 100 % (mass fraction) which 10 mm cells are used shown in Table 3. BSISO17058:2004 7Table 3 Calibration solution for arsenic content between 0, 030 % (mass fraction) and 0, 100 % (mas

48、s fraction) for which 10 mm cells are used Volume of arsenic standard solution (4.11.2) ml Corresponding mass of arsenic g Arsenic content of the test sample % (mass fraction) Test portion of 0,10 g 0 a0 0 2,0 20 0,020 4,0 40 0,040 6,0 60 0,060 8,0 80 0,080 10,0 100 0,100 aZero member. 8 Expression

49、of results 8.1 Method of calculation Convert the absorbance of the test solution and of the blank test solution to micrograms of arsenic by means of the calibration graph (see 7.4). The arsenic content, W As , expressed as a mass fraction in percent, is given by the equation 01 As 6 () 100 10 mm W m = () 01 4 10 mm m = where m 0is the mass, expressed in micrograms of arsenic, in the test solution; m 1is the mass, expressed in