BS 6200-3 34 3-1990 Sampling and analysis of iron steel and other ferrous metals - Methods of analysis - Determination of vanadium - Steel and cast iron flame atomic absorption spe.pdf

1、BRITISH STANDARD BS 6200-3.34.3: 1990 ISO9647:1989 Sampling and analysis of iron, steel and other ferrous metals Part3: Methods of analysis Section3.34 Determination of vanadium Subsection3.34.3 Steel and cast iron: flame atomic absorption spectrometric methodBS6200-3.34.3:1990 This British Standard

2、, having been prepared under the directionof the Iron and Steel Standards Policy Committee, waspublished under the authorityof the Board of BSIandcomes into effect on 31 August1990 BSI10-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comme

3、nt87/43479 DC ISBN 0 580 18430 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Iron and Steel Standards Policy Committee (ISM/-) to Technical Committee ISM/18, upon which the following bodies were represented: BCIRA British Forging Ind

4、ustry Association British Steel Industry Department of Trade and Industry (Laboratory of the Government Chemist) Ferro Alloys and Metals Producers Association Ministry of Defence Amendments issued since publication Amd. No. Date CommentsBS6200-3.34.3:1990 BSI 10-1999 i Contents Page Committees respo

5、nsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling 2 7 Procedure 2 8 Expression of results 4 9 Test report 5 Annex A (informative) Additional information on the international co-operative tests 6 Annex B (informative)

6、 Graphical representation of precision data 7 Annex C (normative) Procedures for the determination of instrumental criteria 8 Figure B.1 Logarithmic relationship between vanadium content % (m/m) and repeatability r or reproducibility R and R w 7 Table 1 3 Table 2 3 Table 3 5 Table A.1 6 Publication(

7、s) referred to Inside back coverBS6200-3.34.3:1990 ii BSI 10-1999 National foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards Policy Committee. It is identical with ISO9647:1989 “Steel and iron Determination of vanadium content Flame atomic absor

8、ption spectrometric method”, published by the International Organization for Standardization (ISO). The Technical Committee has reviewed the provisions of ISO377, ISO385-1 and ISO648, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this st

9、andard. Related British Standards for ISO377:1985, ISO385-1:1984 and ISO648:1977 are, respectively, BS1837:1970 “Methods for the sampling of iron, steel, permanent magnet alloys and ferro-alloys”, BS846:1985 “Specification for burettes” and BS1583:1986 “Specification for one-mark pipettes”. Appropri

10、ate procedures from ISO377 will be incorporated in BS6200-2 “Methods of sampling and sample preparation”, which will be published in due course and which will supersede BS1837. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are r

11、esponsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO1042:1983 BS1792:1982 Specification for one-mark volumetric flasks (Identical) BS5497 Prec

12、ision of test methods ISO5725:1986 Part1:1987 Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to10, an inside back cov

13、er and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6200-3.34.3:1990 BSI 10-1999 1 1 Scope This International Standard specifies a flame atomic absorption spectrom

14、etric method for the determination of vanadium in steel and iron. The method is applicable to vanadium contents between0,005% (m/m) and1,0% (m/m), provided that the tungsten content in the test portion is not higher than10mg and/or the titanium content is not higher than5mg. 2 Normative references T

15、he following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard

16、are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO377:1985, Wrought steel Selection and preparation of samples and test pieces. ISO385-1:1984, Labo

17、ratory glassware Burettes Part1: General requirements. ISO648:1977, Laboratory glassware One-mark pipettes. ISO1042:1983, Laboratory glassware One-mark volumetric flasks. ISO5725:1986, Precision of test methods Determination of repeatability and reproducibility for a standard test method by inter-la

18、boratory tests. 3 Principle Dissolution of a test portion in hydrochloric, nitric and perchloric acids. Addition of aluminium solution as spectrochemical buffer. Spraying the solution into a dinitrogen monoxide-acetylene flame. Spectrometric measurement of the atomic absorption of the318,4nm spectra

19、l line emitted by a vanadium hollow cathode lamp. 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Pure iron, containing less than0,0005% (m/m) of vanadium, or of low known vanadium c

20、ontent. 4.2 Hydrochloric acid, about1,19g/ml. 4.3 Nitric acid, about1,40g/ml. 4.4 Perchloric acid, about1,67g/ml. 4.5 Hydrochloric acid, about1,19g/ml, diluted1+50. 4.6 Aluminium, solution,20g/l. Dissolve90g of aluminium chloride hexahydrate (AlCl 3 6H 2 O) in about300ml of water, add5ml of hydrochl

21、oric acid(4.2), dilute to500ml with water and mix. 4.7 Vanadium, standard solutions. 4.7.1 Stock solution, corresponding to2g of V per litre. 4.7.1.1 Preparation using vanadium metal Weigh, to the nearest0,001g,1,000g of high purity vanadium purity 99,9% (m/m) and dissolve in30ml of aqua regia mix t

22、hree volumes of hydrochloric acid(4.2) with one volume of nitric acid(4.3). Heat to evaporate to just before dryness and add20ml of hydrochloric acid(4.2). Cool and transfer the solution quantitatively to a500ml one-mark volumetric flask, dilute to the mark with water and mix. 1ml of this solution c

23、ontains2mg of V. 4.7.1.2 Preparation using ammonium metavanadate Dry several grams of ammonium metavanadate (NH 4 VO 3 ) purity99,9% (m/m) in an air oven at100 C to105 C (see the note) for at least1h and cool to room temperature in a desiccator. Weigh2,296g of the dried product into a600ml beaker, a

24、dd about400ml of hot water and gently simmer to dissolve. Cool, transfer to a500ml one-mark volumetric flask, dilute to the mark with water and mix. 1ml of this solution contains2mg of V. NOTEA drying temperature over110 C will cause decomposition of ammonium metavanadate. Keep strictly to the dryin

25、g temperature specified. 4.7.2 Standard solution, corresponding to0,08g of V per litre. Transfer10,0ml of the stock solution(4.7.1) into a250ml one-mark volumetric flask, dilute to the mark with water and mix. Prepare this standard solution immediately before use. 1ml of this standard solution conta

26、ins0,08mg of V. 5 Apparatus All volumetric glassware shall be class A, in accordance with ISO385-1, ISO648 or ISO1042 as appropriate. Ordinary laboratory apparatus, andBS6200-3.34.3:1990 2 BSI 10-1999 5.1 Atomic absorption spectrometer A vanadium hollow cathode lamp; supplies of dinitrogen monoxide

27、and acetylene sufficiently pure to give a steady clear red-feather flame, free from water and oil, and free from vanadium. The atomic absorption spectrometer used will be satisfactory if after optimization according to7.3.4 the limit of detection and characteristic concentration are in reasonable ag

28、reement with the values given by the manufacturer and if it meets the precision criteria given in5.1.1 to5.1.3. It is also desirable that the instrument should conform to the additional performance requirement given in5.1.4. 5.1.1 Minimum precision (see clauseC.1) Calculate the standard deviation of

29、10 measurements of the absorbance of the most concentrated calibration solution. The standard deviation shall not exceed1% of the mean absorbance. Calculate the standard deviation of10 measurements of the absorbance of the least concentrated calibration solution (excluding the zero member). The stan

30、dard deviation shall not exceed0,5% of the mean absorbance of the most concentrated calibration solution. 5.1.2 Limit of detection (see clauseC.2) This is defined as twice the standard deviation of10 measurements of the absorbance of a solution containing the appropriate element of a concentration l

31、evel selected to give an absorbance just above that of the zero member. The limit of detection of vanadium in a matrix similar to the final test portion solution shall be better than0,34g of V per millilitre. 5.1.3 Graph linearity (see clauseC.3) The slope of the calibration graph covering the top20

32、% of the concentration range (expressed as a change in absorbance) shall not be less than0,7times the value of the slope for the bottom20% of the concentration range determined in the same way. For instruments with automatic calibration using two or more standards, it shall be established prior to t

33、he analysis, by obtaining absorbance readings, that the above requirements for graph linearity are fulfilled. 5.1.4 Characteristic concentration (see clauseC.4) The characteristic concentration for vanadium in a matrix similar to the final test portion solution shall be better than14g of V per milli

34、litre. 5.2 Ancillary equipment A strip chart recorder and/or digital readout device is recommended to evaluate the criteria of5.1.1 to5.1.3 and for all subsequent measurements. Scale expansion can be used until the noise observed is greater than the readout error and is always recommended for absorb

35、ances below0,1. If scale expansion has to be used and the instrument does not have the means to read the value of the scale expansion factor, the value can be calculated by measuring a suitable solution with and without scale expansion and simply dividing the signal obtained. 6 Sampling Carry out sa

36、mpling in accordance with ISO377 or appropriate national standards for iron. 7 Procedure WARNING Perchloric acid vapour may cause explosions in the presence of ammonia, nitrous fumes or organic material in general. 7.1 Test portion Weigh a test portion according to the presumed vanadium content as f

37、ollows: a) for vanadium contents from0,005% (m/m) to less than0,2% (m/m), a test portion of approximately1,00g, to the nearest0,001g; b) for vanadium contents from0,2% (m/m) to1,0% (m/m), a test portion of approximately0,20g, to the nearest0,0002g. 7.2 Blank test Parallel with the determination and

38、following the same procedure, carry out a blank test using the same quantities of all the reagents including the pure iron(4.1). 7.3 Determination 7.3.1 Preparation of the test solution Place the test portion(7.1) in a250ml beaker. Add10ml of hydrochloric acid(4.2) and4ml of nitric acid(4.3) and cov

39、er the beaker with a watch-glass. After effervescence ceases, add10ml of perchloric acid(4.4) and evaporate the solution until fumes of perchloric acid are visible, remove the watch-glass and evaporate until no more fumes come out of the beaker.BS6200-3.34.3:1990 BSI 10-1999 3 Allow to cool, add10ml

40、 of hydrochloric acid(4.2) and20ml of water, and heat gently to dissolve the salts. Filter through a medium texture filter paper into a100ml one-mark volumetric flask. Wash with warm hydrochloric acid(4.5), and add the washings to the flask. Cool, add10,0ml of aluminium solution(4.6), dilute to the

41、mark with water and mix. 7.3.2 Preparation of the calibration solutions 7.3.2.1 Vanadium content0,2% (m/m) Introduce into a series of seven250ml beakers(1,00 0,01)g of the pure iron(4.1), add10ml of hydrochloric acid(4.2) and4ml of nitric acid(4.3) to each beaker and cover them with watch-glasses. A

42、fter effervescence ceases, cool, then respectively add, using a burette, the volumes of vanadium standard solution(4.7.2) indicated in Table 1. Table 1 Proceed as specified in7.3.1 from “add10ml of perchloric acid(4.4).”(2 ndsentence of1 stparagraph) to the end. 7.3.2.2 Vanadium content between0,2%

43、(m/m) and1,0% (m/m) Introduce into a series of seven250ml beakers(0,20 0,01)g of the pure iron(4.1), add10ml of hydrochloric acid(4.2) and4ml of nitric acid(4.3) to each beaker and cover them with watch-glasses. After effervescence ceases, cool, then respectively add, using a burette, the volumes of

44、 vanadium standard solution(4.7.2) indicated in Table 1. Proceed as specified in7.3.1 from “add10ml of perchloric acid(4.4).”(2 ndsentence of1 stparagraph) to the end. 7.3.3 Adjustment of atomic absorption spectrometer See Table 2. Table 2 7.3.4 Optimizing the atomic absorption spectrometer settings

45、 Follow the manufacturers instructions for preparing the instrument for use. When the current to the lamp, the wavelength and the flow of gas have been adjusted and the burner lit, spray water until the indication has stabilized. Set the absorbance value at zero using the zero member(7.3.2). Choose

46、a damping setting or integration time to give a signal steady enough to fulfil the precision criteria of5.1.1 to5.1.3. Adjust the flame to a red feather and the observation height in the flame to about20mm. Spraying alternately the calibration solution of highest concentration and the zero member, a

47、djust the gas flow and burner position (horizontally, vertically and rotationally) until the difference in absorbance between the calibration solutions is at a maximum. Check that the spectrometer is set accurately on the required wavelength. Evaluate the criteria of5.1.1 to5.1.3 and the additional

48、performance requirement of5.1.4 to ensure that the instrument is suitable for the determination. Volume of vanadium standard solution(4.7.2) ml Corresponding mass of vanadium mg 0 a2,5 5,0 10,0 15,0 20,0 25,0 0 0,20 0,40 0,80 1,20 1,60 2,00 a Zero member. Type of lamp Wavelength Flame Lamp current B

49、andwidth Vanadium hollow cathode 318,4nm Dinitrogen monoxide-acetylene red-feather flame adjusted for maximum vanadium response Follow manufacturers recommendations Follow manufacturers recommendations NOTEThe manufacturers recommendations should be closely followed and particular attention is drawn to the following safety points: a) the explosive nature of acetylene, and regulations concerning its use; b) the need to shield the eyes of the operator from ultraviolet radiation by means of tinted glass; c) the need to keep the burner