BS 6783-14-1994 Sampling and analysis of nickel ferronickel and nickel alloys - Method for the determination of total boron content of nickel and nickel alloys by curcumin molecula.pdf

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1、BRITISH STANDARD BS 6783-14: 1994 ISO 11436: 1993 Sampling and analysis of nickel, ferronickel and nickel alloys Part 14: Method for the determination of total boron content of nickel, and nickel alloys by curcumin molecular absorption spectrometry UDC 669.245:543.422:546.27BS6783-14:1994 This Briti

2、sh Standard, having been prepared under the directionof the Non-ferrous Metals Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15 June 1994 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference NF

3、M/10 Draft for comment 92/38328 DC ISBN 0 580 23363 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Non-ferrous Metals Standards Policy Committee (NFM/-) to Technical Committee NFM/10, upon which the following bodies were represented:

4、Association of Bronze and Brass Founders British Non-ferrous Metals Federation British Stainless Steel Association British Steel Industry Department of Trade and Industry (Laboratory of the Government Chemist) Engineering Equipment and Materials Users Association Institute of British Foundrymen Lond

5、on Metal Exchange Ministry of Defence Nickel Development Institute Non-ferrous Metal Stockists Steel Casting Research and Trade Association Coopted members Amendments issued since publication Amd. No. Date CommentsBS6783-14:1994 BSI 10-1999 i Contents Page Committees responsible Inside front cover N

6、ational foreword ii 1 Scope 1 2 Normative reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling and sample preparation 2 7 Procedure 2 8 Expression of results 3 9 Test report 4 Annex A (informative) Examples of aluminium alloy blocks 5 Figure A.1 Example of an aluminium alloy block 1 5 Fig

7、ure A.2 Example of an aluminium alloy block 2 6 Figure A.3 Example of an aluminium alloy block 3 7 Table 1 Boron calibration solutions 3 Table 2 Composition of test samples 4 Table 3 Results of statistical analysis 4 List of references Inside back coverBS6783-14:1994 ii BSI 10-1999 National foreword

8、 This Part of BS 6783 has been prepared under the direction of the Non-ferrous Metals Standards Policy Committee. It is identical with ISO 11436:1993 Nickel and nickel alloys Determination of total boron content Curcumin molecular absorption spectrometric method, published by the International Organ

9、ization for Standardization (ISO). At present this British Standard consists of 15 Parts all concerned with analysis of nickel, ferronickel and nickel alloys. Further International Standards are in preparation on sampling and analysis of nickel, ferronickel and nickel alloys and, when available, the

10、se will be published as further Parts of this British Standard. 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 does not of itself confer immunity f

11、rom legal obligations. Cross-reference International Standard Corresponding British Standard ISO 5725:1986 BS 5497 Precision of test methods Part 1:1987 Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests (Identical) Summary of pages

12、This document comprises a front cover, an inside front cover, pagesi andii, pages1 to8, an inside back cover 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.BS6783-

13、14:1994 BSI 10-1999 1 1 Scope This International Standard specifies a molecular absorption spectrometric method for the determination of the total boron content in the range of 4 g/t to 240 g/t in nickel and nickel alloys. NOTE 1A possible chemical interference from rhenium has been identified. 2 No

14、rmative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this Intern

15、ational Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 5725:1986, Precision of test methods Determination of repeatability and reprod

16、ucibility for a standard test method by inter-laboratory tests. 3 Principle Dissolution of a test portion in hydrochloric and nitric acids. Decomposition of resistant boron compounds (e.g. boron nitrides) by fuming the sample solution with phosphoric and sulfuric acids at not less than 290 C for 30

17、min. Formation of the boron curcumin complex in a buffered acetic acid and sulfuric acid medium, and measurement of the absorbance of the test solution at a wavelength of 543 nm. 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distil

18、led water or water of equivalent purity. 4.1 Hydrochloric acid, 20= 1,18 g/ml. 4.2 Sulfuric acid, 20= 1,84 g/ml. 4.3 Nitric acid, 20= 1,41 g/ml. 4.4 Phosphoric acid, 20= 1,71 g/ml. 4.5 Sodium hypophosphite, monohydrate (NaH 2 PO 2 .H 2 O). 4.6 Acetic acid, glacial, 20= 1,05 g/ml. The reagent must be

19、 free from aldehydes. Aldehyde test procedure: Transfer 20 ml of the acetic acid to a 50 ml beaker and add 1 ml of 1 g/l potassium permanganate solution. The colour should not disappear within 10 min. If aldehydes are present, an easily visible brown colour will develop in 15 min. 4.7 Acetic acid-su

20、lfuric acid mixture, 1 + 1. Add in small portions, while stirring and cooling under running water, one volume of the sulfuric acid(4.2) to one volume of the acetic acid (4.6). 4.8 Acetate buffer, solution. Dissolve 225 g of ammonium acetate (CH 3 COONH 4 ) in 400 ml of water. Add 300 ml of the aceti

21、c acid(4.6). Filter the solution through a medium filter paper and dilute to 1 000 ml. Store in a polyethylene bottle. 4.9 Sodium fluoride, solution. Dissolve 4 g of sodium fluoride (NaF) in 100 ml of water and mix. 4.10 Boron, standard reference solution (100 mg/l). Weigh, to the nearest 0,000 1 g,

22、 0,285 8 g of boric acid (H 3 BO 3 ) and transfer it to a 500 ml one-mark volumetric flask. Dissolve the acid in water, make up to the mark and mix. Store the solution in a polyethylene flask. 4.11 Boron, standard solution (2 mg/l). Transfer 20,0 ml of the boron stock solution (4.10) to a 1 000 ml o

23、ne-mark volumetric flask. Dilute to volume with water and mix. Store the solution in a polyethylene flask. Prepare freshly before use. 4.12 Curcumin, solution. Dissolve 0,125 g of curcumin (C 26 H 20 O 6 ) in 60 ml of the acetic acid (4.6) in a polyethylene or quartz vessel, by heating in a water ba

24、th and using a magnetic stirrer. Cool and transfer to a 100 ml plastics volumetric flask (5.3). Dilute to volume with the acetic acid (4.6) and mix. This solution must be prepared freshly before use. 5 Apparatus All glassware and plastics flasks used in this method must be rinsed first with the acet

25、ic acid(4.6), then with water and finally dried. 5.1 Quartz conical flasks, of capacity 100 ml, with quartz or polypropylene covers. 5.2 Aluminium alloy block, recommended but not essential, which allows a temperature of 290 C to be achieved and sustained throughout the fuming period. The block (see

26、 Figure A.1, Figure A.2 and Figure A.3) has holes designed to fit the 100 ml quartz flasks exactly and is heated by surface contact with a hotplate which enables the temperature of the aluminium block to be controlled up to about 320 C. 5.3 Plastics volumetric flasks, of capacity 50 ml and100 ml. 5.

27、4 Plastics flasks, of capacity 100 ml, 500 ml and 1 000 ml.BS6783-14:1994 2 BSI 10-1999 5.5 Molecular absorption spectrometer, capable of measuring absorbance at a wavelength of 543 nm using a spectral bandwidth of 10 nm or less. Thewavelength setting shall be accurate to 2 nm, as measured by the ab

28、sorption maximum of a holmium oxide filter at 536 nm or by another suitable calibration method. The precision of the absorption measurement for the solution of highest absorbance shall have a repeatability, expressed as relative deviation, of 0,3 % or better. 6 Sampling and sample preparation 6.1 Sa

29、mpling and preparation of the laboratory sample shall be carried out by normal agreed procedures or, in the case of dispute, according to the relevant International Standard. 6.2 The laboratory sample is normally in the form of millings or drillings and no further preparation of the sample is necess

30、ary. 6.3 If it is suspected that the laboratory sample is contaminated with oil or grease from the milling or drilling process, it shall be cleaned by washing with high-purity acetone and dried in air. 6.4 If the laboratory sample contains particles or pieces of widely varying sizes, the test sample

31、 should be obtained by riffling. 7 Procedure 7.1 Preparation of the aluminium block Place the aluminium block on a heat source. Adjust the surface temperature of the source, until a constant temperature is reached in the range of280 C to 320 C, in a test flask containing 10 ml of sulfuric acid (4.2)

32、. (The temperature can be measured with a thermometer graduated from 0 C to 350 C.) NOTE 2Equivalent results can be obtained without an aluminium block, provided that the temperature of each vessel is measured with a thermometer in a sleeve and is maintained at a minimum of 290 C. 7.2 Test portion a

33、nd preparation of test solution 7.2.1 Weigh to the nearest 0,001 g approximately 0,5 g of the test sample, for contents less than120 g/t; 0,25 g of the test sample, for contents between120 g/t and 240 g/t. 7.2.2 Place the test portion in the 100 ml quartz conical flask (5.1). Add 10 ml of the hydroc

34、hloric acid (4.1) and 5 ml of the nitric acid (4.3). Place the quartz or polypropylene cover on the flask and leave it at ambient temperature in order to avoid possible loss of boron at higher temperatures. Wait until dissolution is complete or until effervescence ceases. Swirl occasionally when sam

35、ples are difficult to dissolve. 7.2.3 Carefully add 10 ml of the phosphoric acid(4.4) and 5 ml of the sulfuric acid (4.2). Place the quartz flask without its cover in a hole in the hot aluminium alloy block. Heat until the sulfuric acid starts to fume, replace the cover and continue heating for 30 m

36、in. Remove the flask from the block and allow to cool. Dilute the syrupy solution with30ml of water. Warm and stir. 7.2.4 Add 5 ml of the hydrochloric acid (4.1) and bring to boiling. Add 3 g of sodium hypophosphite(4.5) and allow to boil gently for15min. Remove from the heat source and allow to coo

37、l. Transfer the solution quantitatively to a50ml plastics volumetric flask (5.3). Dilute to volume with water and mix. NOTE 3In test solutions made from samples containing copper, a precipitate will appear. This precipitate will not interfere if it is allowed to settle before an aliquot is taken. 7.

38、3 Sample compensating solution Transfer 1,0 ml of the test solution (7.2.4) to a100ml plastics flask (5.4). Add 0,2 ml of the sodium fluoride solution (4.9), avoiding contact with the flask wall. Carefully swirl the small volume of solution and allow to stand for 1 h. Continue with the colour develo

39、pment as directed in 7.4.2. NOTE 4This solution should be ready before the colour development step is started, since the curcumin complex solution and the compensation solution should be ready for measurement at the same time. 7.4 Colour development 7.4.1 Transfer 1,0 ml of the test solution (7.2.4)

40、 to a100 ml plastics volumetric flask (5.3). 7.4.2 Add the following quantities of reagents to the two flasks (7.3 and 7.4.1) and mix after each addition by swirling to avoid contact with the stoppers. 6,0 ml of the acetic acid-sulfuric acid mixture(4.7). Avoid contact of the pipette with the neck a

41、nd sides of the flask. 6,0 ml of the curcumin solution (4.12). Stopper the flask and allow to stand for 2 h 30 min for complete development of the colour. 1,0 ml of the phosphoric acid (4.4) to stabilize the colour. Shake and allow to stand for30min.BS6783-14:1994 BSI 10-1999 3 30,0 ml of the acetat

42、e buffer solution (4.8). Thesolution becomes orange. Stopper and shake. Allow to stand for exactly 15 min. NOTE 5In order to carry out the spectrometric measurements on all the solutions, whilst keeping exactly to the final waiting time of 15 min after the addition of the acetate buffer solution, it

43、 is advisable to group the solutions into series of six measurements. If the waiting time is not strictly adhered to, formation of a cloudiness in the solutions may be observed and, consequently, erroneous results obtained. 7.5 Spectrometric measurement 7.5.1 Using 2 cm cells, measure the absorbance

44、 of the boron curcumin complex test solution (from7.4.1) and the corresponding compensating solution (from 7.3) against water as the reference, at a wavelength of 543 nm with the molecular absorption spectrometer (5.5). 7.5.2 Subtract the absorbance of the compensating solution from the absorbance o

45、f the test solution containing the boron curcumin complex. 7.6 Blank test Carry out a reagent blank test in parallel with the determination, following the same procedure and using the same quantities of all the reagents. Subtract the measured absorbance of the blank compensating solution from the ab

46、sorbance of the blank solution. 7.7 Calibration 7.7.1 Using a burette, transfer the boron standard solution (4.11) as indicated in the Table 1, to a series of six 100 ml quartz conical flasks (5.1). Continue as directed for the test sample in 7.2.2 through 7.5, omitting 7.3. 7.7.2 Subtract the absor

47、bance of the first “zero” member from each solution containing boron, and plot the net absorbance against the mass, in micrograms, of boron in the measured solution. NOTE 6The compensation solutions (7.3) do not have to be prepared, since all solutions have the same matrix. 7.8 Number of determinati

48、ons Carry out the determination at least in duplicate. 8 Expression of results 8.1 Calculation 8.1.1 Convert the net absorbances of the test solution (7.5.2) and of the blank test (7.6) into micrograms of boron using the calibration graph (see 7.7.2). 8.1.2 Calculate the boron content w B , expresse

49、d in grams per tonne, of the test portion using the formula 8.2 Precision 8.2.1 Laboratory tests Nine laboratories in four countries participated in the testing of this procedure using four samples of nickel alloys and two certified reference materials. The samples were analysed in duplicate on two different days. The nominal composition of the samples is given in Table 2. Table 1 Boron calibration solutions where m 0 is the mass, in grams, of the test portion (see 7.2.1); m 1 is the mass, in micrograms, of boron found