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1、BRITISH STANDARD BS 1728-21: 1973 Methods for The analysis of aluminium and aluminium alloys Part 21: Zinc (atomic absorption method) UDC 543:669.71 + 543.422:546.47:669.71 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-21:1973 This
2、 British Standard, having been approved by the Non-ferrous Metals Industry Standards Committee, was published under the authority of the Executive Board on 22 October 1973 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference NFE/3 Draft for comment 71/421
3、38 ISBN 0 580 07577 X Co-operating organizations The Non-ferrous Metals Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Aluminium Federation* A
4、ssociation of Bronze and Brass Founders British Electrical and Allied Manufacturers Association British Lead Manufacturers Association British Non-ferrous Metals Federation British Non-ferrous Metals Federation-High Conductivity Copper Group British Non-ferrous Metals Research Association* Copper De
5、velopment Association Department of Trade and Industry (Marine Division) Electric Cable Makers Confederation Institute of British Foundrymen Institution of Mining and Metallurgy Institution of Production Engineers Institution of Structural Engineers Lead Development Association Light Metal Founders
6、Association* London Metal Exchange Magnesium Industry Council Ministry of Defence, Army Department* Ministry of Defence, Navy Department National Brassfoundry Association Non-ferrous Metal Stockists Post Office Royal Institute of British Architects Society of Motor Manufacturers and Traders Ltd. Tin
7、 Research Institute Zinc Development Association Individual manufacturer The organizations marked with an asterisk in the above list, together with the following, were directly represented on the sub-committee entrusted with the preparation of this British Standard: Association of Light Alloy Refine
8、rs and Smelters Ltd. Department of Trade and Industry Laboratory of the Government Chemist Individual analysts Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-21:1973
9、BSI 12-1999i Contents Page Co-operating organizationsInside front cover Forewordii 1Introduction1 2Apparatus1 3Solutions required1 4Sampling2 5Procedure2 6Calibration2 7Calculation3 8Notes3 Publication referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+0
10、0:00 2006, Uncontrolled Copy, (c) BSI BS 1728-21:1973 ii BSI 12-1999 Foreword This method for the determination of zinc is the twenty-first of a series which will form a complete British Standard under the collective title “Methods for the analysis of aluminium and aluminium alloys”, each being publ
11、ished as a separate part. Other methods in the series are as follows: Part 1: Copper; Part 2: Magnesium; Part 5: Copper (absorptiometric method); Part 6: Iron (volumetric: titanous chloride method); Part 8: Iron (absorptiometric 1 : 10-phenanthroline method); Part 9: Manganese (volumetric arsenite/n
12、itrite method); Part 10: Manganese (absorptiometric method); Part 11: Silicon (perchloric acid method); Part 12: Silicon (absorptiometric molybdenum blue method); Part 13: Titanium (absorptiometric chromotropic acid method); Part 14: Nickel (gravimetric method); Part 15: Nickel (photometric method);
13、 Part 16: Chromium (photometric method); Part 17: Chromium (volumetric method); Part 18: Zinc (ion-exchange-volumetric EDTA or polarographic method); Part 19: Magnesium (atomic absorption method); Part 20: Lead (atomic absorption method); Part 22: Magnesium (volumetric CDTA method). The preparation
14、of this series of methods has been authorized by the Non-ferrous Metals Industry Standards Committee as part of a general programme for the standardization of methods for the sampling and analysis of non-ferrous metals. The methods have been found to give reliable and reproducible results and, while
15、 in some instances they may appear to be lengthy, it should be appreciated that they are primarily intended as “referee” methods to be used in cases of dispute. This method is substantially the same as the corresponding method approved by ISO/TC 79 which will be published as International Standard I
16、SO 26371). NOTEThe title of the British Standard referred to in this standard is given on the inside back cover. 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 Brit
17、ish Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments
18、incorporated. This will be indicated in the amendment table on the inside front cover. 1) In course of preparation. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-21:1973 BSI 12-19991 1 Introduction 1.1 Principle. The sample is diss
19、olved in hydrochloric acid and diluted to a suitable volume and the zinc content is determined by atomic absorption spectrophotometry. 1.2 Range. The method is recommended for zinc contents between 0.005 and 0.20 %. 1.3 Reproducibility. Experiments have been carried out independently by a number of
20、analysts using this method. The degree of reproducibility that can be expected is shown in the following analysis of the results obtained. 2 Apparatus 2.1 Class A volumetric glassware complying with the appropriate British Standards shall be used throughout. The burette used should be graduated in 0
21、.02 ml subdivisions. 2.2 Any atomic absorption spectrophotometer with adequate sensitivity and precision and preferably attached to a chart recorder readout or integrating device and capable of measuring absorption at a wavelength of 213.8 nm. A slot burner with air/acetylene flame. A multi-slot bur
22、ner is advisable when the total solid concentration in the solutions to be aspirated exceeds 0.5 %. 2.3 Zinc hollow cathode lamp. 3 Solutions required All reagents shall be of the highest purity obtainable2) and distilled or demineralized water shall be used throughout. Standard zinc (1 ml N 0.1 mg
23、of zinc). Dissolve 1.0 0.001 g of high purity zinc (99.99 % pure) in 25 ml of hydrochloric acid (50 %). Dilute, transfer to a 1 litre volumetric flask, dilute to the mark and mix. Transfer 100 ml of this solution to a 1 litre volumetric flask, dilute to the mark and mix. Standard zinc (1 ml N 0.01 m
24、g of zinc). Transfer 100 ml of standard zinc solution (1 ml N 0.1 mg of zinc) to a 1 litre volumetric flask, dilute to the mark and mix. Aluminium (4 % w/v). Weigh 40.0 0.01 g of high purity aluminium (Note 8.1) and transfer to a 2 litre beaker. Add in small portions 100 ml of hydrochloric acid (50
25、%), then add a drop of metallic mercury. Heat gently to start the reaction then add in small portions a further 400 ml of hydrochloric acid (50 %). When the reaction subsides add gradually 250 ml of special grade hydrochloric acid (sp.gr. 1.16 1.18) and heat gently if necessary to complete the react
26、ion. Add a few millilitres of hydrogen peroxide (100 vol.) and boil to remove excess hydrogen peroxide. Allow to cool, transfer to a 1 litre volumetric flask, dilute to the mark and mix. Hydrochloric acid (50 % v/v). Dilute 500 ml of special grade hydrochloric acid (sp.gr. 1.16 1.18) to 1 litre and
27、mix. Nitric acid (50 % v/v). Dilute 100 ml of nitric acid (sp.gr. 1.42) to 200 ml and mix. Zinc contentStandard deviation S % 0.0060.0006 0.02 0.04 0.0016 0.100.0026 0.230.0039 2) For certain reagents an extra high quality is now available but this special grade of material is not required unless sp
28、ecifically stated. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-21:1973 2 BSI 12-1999 4 Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS 1499, “Sampling non-f
29、errous metals”. 5 Procedure 5.1 Weigh 1.0 0.001 g of sample, transfer to a 400 ml beaker (Note 8.2) and add 25 ml of hydrochloric acid (50 %) (Note 8.3). Cover with a watchglass and warm gently to complete the dissolution. Add a few millilitres of hydrogen peroxide (100 vol.) and boil to remove exce
30、ss hydrogen peroxide. 5.2 Carry out simultaneously a blank determination following the same procedure and using the same amounts of reagents as with the sample, and replacing the sample by 1.0 0.001 g of high purity aluminium (Note 8.1). 5.3 Filter if necessary through a close-textured filter paper3
31、), wash the precipitate four times with water and add the washings to the sample solution. 5.3.1 For alloys containing up to 1 % of silicon. Discard the filter paper and residue and retain the solution. 5.3.2 For alloys containing more than 1 % of silicon. Transfer the filter paper and residue to a
32、platinum crucible using forceps, dry and ignite to burn off the paper. Allow to cool, add 5 ml of hydrofluoric acid4) and five drops of nitric acid (sp.gr. 1.42). When the reaction has subsided evaporate carefully to dryness (Note 8.4), take up the residue in 5 ml of nitric acid (50 %) and add to th
33、e main solution. 5.4 Transfer the solution to the appropriate size volumetric flask indicated in the table below: Dilute to the mark and mix. 5.5 Aspirate the solution (Note 8.2) and record the values of per cent absorption or absorbance depending upon the instrument and type of read out. 6 Calibrat
34、ion 6.1 To a series of 100 ml volumetric flasks transfer the appropriate volume of aluminium solution (4 %) indicated in the following table, then add from a burette the respective quantities of standard zinc solution (1 ml N 0.01 mg of zinc or 1 ml N 0.1 mg of zinc) as shown in the following table.
35、 6.2 Dilute to the mark and mix. 6.3 Aspirate the solutions (Note 8.2) and record the values of per cent absorption or absorbance depending upon the instrument and type of readout. 6.4 Deduct the absorbance reading for the blank and prepare a calibration graph by plotting absorbance values (see 7. C
36、alculation) against the nominal zinc contents of the solutions. 3) Whatman No. 540 is suitable. 4) This refers to the usual analytical reagent grade of 40 % w/w. Zinc contentVolumetric size flask %ml 0.005 0.05100 0.05 0.20500 Zinc contentAluminium solutionStandard zinc solution 1 ml N 0.01 mg of zi
37、nc Corresponding zinc in sample %mlmlmg 0.005 0.05 (Note 8.5) 250, 5, 100.00, 0.05, 0.10 Standard zinc solution 1 ml N N 0.1 mg of zinc ml 2, 3, 4, 50.20, 0.30, 0.40, 0.50 0.05 0.2550, 1, 2, 3, 4, 50.00, 0.10, 0.20, 0.30, 0.40, 0.50 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT
38、+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-21:1973 BSI 12-19993 7 Calculation If the instrument reads per cent absorption convert this to absorbance. Convert the absorbance reading for the test sample corrected for blank to percentage zinc by means of the calibration graph. 8 Notes 8.1 Millings
39、 or drillings of 99.99 % purity aluminium should be used and these should be cleaned immediately before use with a little nitric acid (sp.gr. 1.42), then washed with water and dried by washing with acetone. 8.2 The sample solution should be prepared at the same time as the calibration standard solut
40、ions and aspirated immediately after the calibration solutions and blank without altering the instrument settings. After the last sample solution has been aspirated, it is advisable to aspirate the most concentrated standard solution once more. This is to ensure that instrument conditions have not a
41、ltered (i.e. atomizer blocked, etc.). 8.3 For samples which are difficult to attack with hydrochloric acid add a drop of metallic mercury. 8.4 If necessary repeat the treatment with hydrofluoric and nitric acids. 8.5 For zinc contents between 0.005 and 0.02 % it is advisable to restrict the calibrat
42、ion curve to the first four dilutions, and then to use suitable scale expansion. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) B
43、SI BS 1728-21:1973 BSI 12-1999 Publication referred to This standard makes reference to the following British Standard: BS 1499, Sampling non-ferrous metals. BSI Certification Trade Mark The Kitemark The British Standards Institution is the owner of a registered certification trade mark. It is usual
44、ly associated with the words “approved to British Standard” as shown below, the number of the relevant British Standard being added. This mark may be used only by those licensed under the certification mark scheme operated by BSI. The presence of this mark on or in relation to a product is an assura
45、nce that the goods have been produced under a system of supervision, control and testing, operated during manufacture and including periodical inspection of the manufacturers works in accordance with the certification mark scheme of BSI designed to ensure compliance with a British Standard. Licensed
46、 Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-21: 1973 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on
47、standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the qua
48、lity of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: 020 8996 9000. Fax: 020 8996 74
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