1、BRITISH STANDARD BS6721-6: 1989 ISO4741:1984 Sampling and analysis of copper and copper alloys Part6: Method for determination of phosphorus in copper and copper alloys by spectrophotometry ISO title: Copper and copper alloys Determination of phosphorus content Molybdovanadate spectrometric method U
2、DC 669.3:543.42.062:543.847:620.1BS6721-6:1989 This British Standard, having been prepared under the directionof the Non-ferrous Metals Standards Committee, waspublished under the authorityof the Board of BSIandcomes into effect on 28February1989 BSI 11-1999 The following BSI references relate to th
3、e work on this standard: Committee referenceNFM/34 Draft (ref.86/38268) announced inBSI News January1988 ISBN 0 580 17119 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Non-ferrous Metals Standards Committee (NFM/-) to Technical Commi
4、tteeNFM/34, upon which the following bodies were represented: British Non-ferrous Metals Federation Copper Development Association London Metal Exchange Non-ferrous Metal Stockists Society of British Aerospace Companies Limited Coopted members The following bodies were also represented in the drafti
5、ng of the standard, through subcommittees and panels: BNF Metals Technology Centre British Bronze and Brass Ingot Manufacturers Association Copper Smelters and Refiners Association Ministry of Defence National Brassfoundry Association Coopted members Amendments issued since publication Amd. No. Date
6、 of issue CommentsBS6721-6:1989 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Procedure 1 6 Expression of results 3 7 Test report 3BS6721-6:1989 ii BSI 11-1999 National foreword
7、 This Part of BS6721 has been prepared under the direction of the Non-ferrous Metals Standards Committee. BS6721 is a multi-part standard and describes methods of sampling and analysis for copper and copper alloys. It is intended that Parts1 to3 of BS6721 will describe methods of sampling copper and
8、 copper alloys in various forms. The remaining Parts will give methods for the determination of individual elements in copper and copper alloys. This Part of BS6721 is identical with ISO4741:1984 “Copper and copper alloys Determination of phosphorus content Molybdovanadate spectrometric method”, pub
9、lished by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in
10、 British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they
11、 should be read as “Part of BS6721”. In British Standards it is current practice to use the symbol “L” for litre (and in its submultiples) rather than“l”, and to use the spelling “sulphur”, etc., instead of “sulfur”, etc. WARNING. Throughout this Part of BS6721, normal precautions concerning the use
12、 of perchloric acid in laboratory work should be observed. 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 from l
13、egal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to3 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
14、cover.BS6721-6:1989 BSI 11-1999 1 1 Scope and field of application This International Standard specifies a molybdovanadate spectrometric method for the determination of the phosphorus content of copper and copper alloys. The method is applicable to the determination of phosphorus contents between0,0
15、005 and0,5% (m/m) in all types of copper and copper alloys listed in International Standards. 2 Principle Dissolution of a test portion with nitric acid. Elimination of interfering elements by fuming with perchloric, hydrofluoric and hydrobromic acids. Decomposition of insoluble phosphates by fusion
16、 with sodium carbonate. For concentrations below0,01% (m/m), extraction of phosphorus as phosphomolybdic acid and spectrometric determination as molybdenum blue; for concentrations between0,005 and0,5% (m/m), extraction and spectrometric determination as phosphovanadomolybdic acid. 3 Reagents During
17、 the analysis, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 3.1 Nitric acid, 1,2g/ml. 3.2 Hydrofluoric acid,40% (V/V), 1,14g/ml. 3.3 Perchloric acid, 1,67g/ml 1) . 3.4 Hydrobromic acid, 1,50g/ml. 3.5 Isobutanol 3.6 Methanol 3.7 Methyl isob
18、utyl ketone 3.8 Ammonium molybdate solutionI. Dissolve50g of ammonium molybdate tetrahydrate (NH 4 ) 6 Mo 7 O 24 .4H 2 O in250ml of water. Add a solution of115ml of the perchloric acid(3.3) and500ml of water at room temperature. Dilute to1000ml with water. After prolonged storage, a white precipitat
19、e may form. While this residue will not affect the analysis, care should be taken to prevent its contamination of the aliquot used in the analysis. Immediately before use, the aliquot used in the analysis should be purified by shaking with10ml of the isobutanol(3.5). 3.9 Ammonium molybdate solutionI
20、I. Dissolve150g of ammonium molybdate tetrahydrate (NH 4 ) 6 Mo 7 O 24 .4H 2 O, in1000ml of water. 3.10 Tin(II) chloride, stock solution. Dissolve10g of tin(II) chloride dihydrate (SnCl 2 .2H 2 O) in25ml of hydrochloric acid, 1,19g/ml. Prepare this solution fresh before use. 3.11 Tin(II) chloride, w
21、orking solution. Dilute1ml of the tin(II) chloride stock solution(3.10) with10ml of sulfuric acid, 1,54g/ml, and water to200ml. Prepare this solution fresh before use. 3.12 Ammonium vanadate solution. Dissolve2,5g of ammonium vanadate(NH 4 VO 3 ) in1000ml of water. 3.13 Citric acid solution. Dissolv
22、e500g of citric acid in1000ml of water. 3.14 Phosphorus, standard solution, corresponding to10mg of P per litre. Dissolve0,8786g of potassium dihydrogen orthophosphate (KH 2 PO 4 ), freshly dried at105 C, with water and dilute to1000ml. Dilute a50ml aliquot portion of this solution to1000ml. 1ml of
23、this standard solution contains104g of P. 4 Apparatus All vessels shall be free of contamination by phosphorus. Cleaning with hot hydrochloric acid, 1,19g/ml, is recommended. Ordinary laboratory apparatus, and 4.1 PTFE beakers, capacity100ml. 4.2 Spectrometer, fitted with cells of optical path lengt
24、hs1 and4cm. 5 Procedure 5.1 For copper and copper alloys free of zirconium, titanium, niobium and/or tantalum, with phosphorus contents between0,0005 and0,01% (m/m) 5.1.1 Weigh, to the nearest0,001g,1,000g of the test sample. 5.1.2 Dissolve the test portion in a PTFE beaker(4.1) with10,0ml of the ni
25、tric acid(3.1). Heat gently, if necessary. To eliminate silicon, add0,50ml of the hydrofluoric acid(3.2) and10,0ml of the perchloric acid(3.3) and heat until fuming begins. 1) See national foreword for warning on use of perchloric acid.BS6721-6:1989 2 BSI 11-1999 5.1.3 Dilute the solution with10ml o
26、f water and add10,0ml of the hydrobromic acid(3.4). To eliminate interference from arsenic, antimony and tin, heat gently until fuming begins again. If tin contents of1% (m/m) are present, repeat the fuming step with10,0ml of the hydrobromic acid(3.4). 5.1.4 Dissolve the copper bromide formed during
27、 the fuming steps by adding several millilitres of the nitric acid(3.1) and bring to fuming. Dilute this solution with30ml of water. Heat to boiling for10min, then cool to room temperature. 5.1.5 If the phosphorus content is expected to be0,005% (m/m), dilute the solution from5.1.4 to the mark with
28、water in a100ml one-mark volumetric flask, and transfer a50ml aliquot portion to a125ml separating funnel. 5.1.6 Add10ml of the ammonium molybdate solutionI(3.8) and extract the phosphomolybdic acid with15,0ml of the isobutanol(3.5) by shaking for about30s. After separation of the two phases, transf
29、er the aqueous phase to another separating funnel and repeat the extraction with5,0ml of the isobutanol(3.5). Repeat the extraction a third time with5,0ml of the isobutanol, then discard the aqueous phase. 5.1.7 Combine the three butanolic extracts in the first separating funnel and wash by shaking
30、twice with5ml of water, discarding the wash water each time. To the organic phase, add15ml of the tin(II) chloride solution(3.11) and shake for about30s. Discard the aqueous layer after separation of the phases. Transfer the blue-coloured organic phase to a50ml one-mark volumetric flask and dilute w
31、ith the methanol(3.6) to the mark. 5.1.8 Measure the absorbance immediately using the spectrometer(4.2), fitted with a1cm photometric cell, at623nm, using a1+1 mixture of the isobutanol(3.5) and the methanol(3.6) in the reference cell. Carry a blank test through all steps and correct each result acc
32、ordingly. 5.1.9 Prepare a calibration graph Take aliquot portions of0to8ml of the standard phosphorus solution(3.14) and carry them through all steps of the procedure using exactly the same amounts of reagents. The calibration graph is linear and shows an absorbance of1 for about904g of phosphorus.
33、5.2 For copper and copper alloys free of zirconium, titanium, niobium and/or tantalum, with phosphorus contents between0,005 and0,5% (m/m) 5.2.1 Weigh, to the nearest0,001g, 1,000g of the test sample. 5.2.2 Dissolve the test portion in a PTFE beaker(4.1) with10,0ml of the nitric acid(3.1). Heat gent
34、ly, if necessary. To eliminate silicon, add0,50ml of the hydrofluoric acid(3.2) and10,0ml of the perchloric acid(3.3) and heat until fuming begins. 5.2.3 Dilute the solution with10ml of water and add10,0ml of the hydrobromic acid(3.4). To eliminate interference from arsenic, antimony and tin, heat g
35、ently until fuming begins again. 5.2.4 Dilute the solution with50ml of water and10ml of the nitric acid(3.1). Heat to boiling for10min, then cool to room temperature. 5.2.5 If the phosphorus content is expected to be0,10% (m/m), dilute the solution from5.2.4 to the mark with water in a100ml one-mark
36、 volumetric flask. Transfer a20ml aliquot portion to a beaker, add8ml of the nitric acid(3.1) and8ml of the perchloric acid(3.3), and dilute with water to about60ml, then add10ml of the ammonium vanadate solution(3.12) and15ml of the ammonium molybdate solution II(3.9), while swirling. 5.2.6 After10
37、min, transfer the solution to a separating funnel. Wash the beaker with water and add the washings to the funnel. Dilute with water to a total volume of about100ml. 5.2.7 Add10ml of the citric acid solution(3.13) and extract the phosphovanadomolybdic acid by shaking with20ml of the methyl isobutyl k
38、etone(3.7) for30s. After separation of the phases, draw off the aqueous phase into the original PTFE beaker. Filter the organic phase through a cotton wool plug into a dry50ml one-mark volumetric flask. 5.2.8 Transfer the aqueous phase to the separating funnel and repeat the extraction with20ml of t
39、he methyl isobutyl ketone. Discard the aqueous phase and filter the organic phase into the50ml one-mark volumetric flask as in5.2.7. Wash the separating funnel with5ml of the methyl isobutyl ketone, filter into the volumetric flask, and dilute to the mark with the methyl isobutyl ketone.BS6721-6:198
40、9 BSI 11-1999 3 5.2.9 Measure the absorbance immediately using the spectrometer(4.2), fitted with a4cm photometric cell for phosphorus contents between0,005 and0,03% (m/m) or with a1cm cell for phosphorus contents between0,03 and0,5% (m/m), at436nm. Use methyl isobutyl ketone in the reference cell.
41、Carry a blank test through all steps and correct each result accordingly. 5.2.10 Prepare a calibration graph. Take aliquot portions of0 to30ml of the standard phosphorus solution(3.14) and carry them through all steps of the procedure using exactly the same amounts of reagents. The calibration graph
42、 is linear and shows an absorbance of about0,15 for504g of phosphorus. 5.3 For copper and copper alloys containing zirconium, titanium, niobium and/or tantalum If the sample contains zirconium, titanium, niobium and/or tantalum, phosphorus can be found totally or partially as insoluble phosphates. T
43、he procedure for dissolving these residues is described below. 5.3.1 Dissolve the test portion according to5.1 or5.2. After fuming off the F , Br , and NO 3 , filter the solution through a millipore filter. Wash the filter with hot water until free of acid, then dry and ignite the filter in a small
44、porcelain crucible. Transfer the residue to a small platinum crucible, mix with about0,3g of sodium carbonate and fuse. After cooling, dissolve the melt with a small amount of water. Filter off any insoluble residue and wash with hot water, adding the washings to the filtrate. 5.3.2 Neutralize the c
45、ombined filtrate and washings with the perchloric acid(3.3). Add the neutralized solution to the original copper-containing filtrate. The total volume should not exceed50ml; if necessary, the volume should be reduced by evaporating. 5.3.3 Continue as described in5.1 or5.2. 5.4 Check test Make a prel
46、iminary check of the apparatus by preparing a solution of standard material or a synthetic sample containing a known amount of phosphorus and of composition similar to the material to be analysed, and carrying out the procedure as specified in5.1, 5.2 or5.3. 6 Expression of results By means of the c
47、alibration graph(5.1.9, 5.2.10), determine the mass of phosphorus, expressed in micrograms, of the test portion, corresponding to the absorbance obtained. The phosphorus content, expressed as a percentage by mass, is given by the formula 7 Test report The test report shall include the following part
48、iculars: a) an identification of the sample; b) the reference of the method used; c) the results and the method of expression used; d) any unusual features noted during the determination; e) any operation not included in this International Standard or regarded as optional which might affect the resu
49、lts. where m 0 is the mass, in grams, of the test portion(5.1.1, 5.2.1) or of the aliquot portion taken(5.1.5, 5.2.5); m 1 is the mass, in micrograms, of phosphorus found in the test solution(5.1.7, 5.2.8). m 1 m 0 10 6 -100 m 1 m 0 10 4 - =BS6721-6: 1989 ISO4741:1984 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international leve
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