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 + 543.422:546.47:669.71BS1728-21:1973 This British Standard, having been approved by the Non-ferrousMetals Industry Standards Committee, was published
2、under the authority ofthe Executive Board on 22October 1973 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference NFE/3 Draft for comment 71/42138 ISBN 0 580 07577 X Co-operating organizations The Non-ferrous Metals Industry Standards Committee, under whos
3、e supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Aluminium Federation* Association of Bronze and Brass Founders British Electrical and Allied Manufacturers Association British Lead Man
4、ufacturers Association British Non-ferrous Metals Federation British Non-ferrous Metals Federation-High Conductivity Copper Group British Non-ferrous Metals Research Association* Copper Development Association Department of Trade and Industry (Marine Division) Electric Cable Makers Confederation Ins
5、titute of British Foundrymen Institution of Mining and Metallurgy Institution of Production Engineers Institution of Structural Engineers Lead Development Association Light Metal Founders Association* London Metal Exchange Magnesium Industry Council Ministry of Defence, Army Department* Ministry of
6、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 Research Institute Zinc Development Association Individual manufacturer The organizations marked with an asteri
7、sk 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 Refiners and Smelters Ltd. Department of Trade and Industry Laboratory of the Government Chemist Individual analysts A
8、mendments issued since publication Amd. No. Date of issue CommentsBS1728-21:1973 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Introduction 1 2 Apparatus 1 3 Solutions required 1 4 Sampling 2 5 Procedure 2 6 Calibration 2 7 Calculation 3 8 Notes 3 Publicatio
9、n referred to Inside back coverBS1728-21:1973 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 published as
10、 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/nitrite met
11、hod); 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); Part 16:
12、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 of this se
13、ries 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 in some i
14、nstances 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/TC79 which will be published as International Standard ISO2637 1) .
15、 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 British Standa
16、rd 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, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporate
17、d. This will be indicated in the amendment table on the inside front cover. 1) In course of preparation.BS1728-21:1973 BSI 12-1999 1 1 Introduction 1.1 Principle. The sample is dissolved in hydrochloric acid and diluted to a suitable volume and the zinc content is determined by atomic absorption spe
18、ctrophotometry. 1.2 Range. The method is recommended for zinc contents between0.005and0.20%. 1.3 Reproducibility. Experiments have been carried out independently by a number of analysts using this method. The degree of reproducibility that can be expected is shown in the following analysis of the re
19、sults 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 in0.02ml subdivisions. 2.2 Any atomic absorption spectrophotometer with adequate sensitivity and precision and preferably attac
20、hed to a chart recorder readout or integrating device and capable of measuring absorption at a wavelength of213.8nm. A slot burner with air/acetylene flame. A multi-slot burner is advisable when the total solid concentration in the solutions to be aspirated exceeds0.5%. 2.3 Zinc hollow cathode lamp.
21、 3 Solutions required All reagents shall be of the highest purity obtainable 2)and distilled or demineralized water shall be used throughout. Standard zinc (1ml N 0.1mg of zinc). Dissolve1.0 0.001g of high purity zinc (99.99% pure) in25ml of hydrochloric acid (50%). Dilute, transfer to a1litre volum
22、etric flask, dilute to the mark and mix. Transfer100ml of this solution to a1litre volumetric flask, dilute to the mark and mix. Standard zinc (1mlN 0.01mg of zinc). Transfer100ml of standard zinc solution (1mlN 0.1mg of zinc) to a1litre volumetric flask, dilute to the mark and mix. Aluminium (4% w/
23、v). Weigh40.0 0.01g of high purity aluminium (Note8.1) and transfer to a2litre beaker. Add in small portions100ml of hydrochloric acid (50%), then add a drop of metallic mercury. Heat gently to start the reaction then add in small portions a further400ml of hydrochloric acid (50%). When the reaction
24、 subsides add gradually250ml of special grade hydrochloric acid (sp.gr. 1.161.18) and heat gently if necessary to complete the reaction. Add a few millilitres of hydrogen peroxide (100vol.) and boil to remove excess hydrogen peroxide. Allow to cool, transfer to a1litre volumetric flask, dilute to th
25、e mark and mix. Hydrochloric acid (50% v/v). Dilute500ml of special grade hydrochloric acid (sp.gr. 1.161.18) to1litre and mix. Nitric acid (50% v/v). Dilute100ml of nitric acid (sp.gr.1.42) to200ml and mix. Zinc content Standard deviation S % 0.006 0.0006 0.02 0.04 0.0016 0.10 0.0026 0.23 0.0039 2)
26、 For certain reagents an extra high quality is now available but this special grade of material is not required unless specifically stated. BS1728-21:1973 2 BSI 12-1999 4 Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS1499, “Sa
27、mpling non-ferrous metals”. 5 Procedure 5.1 Weigh1.0 0.001g of sample, transfer to a400ml beaker (Note8.2) and add25ml of hydrochloric acid(50%) (Note8.3). Cover with a watchglass and warm gently to complete the dissolution. Add a few millilitres of hydrogen peroxide (100vol.) and boil to remove exc
28、ess 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 by1.0 0.001g of high purity aluminium (Note8.1). 5.3 Filter if necessary through a close-textured filter paper 3)
29、 , wash the precipitate four times with water and add the washings to the sample solution. 5.3.1 For alloys containing up to1% of silicon. Discard the filter paper and residue and retain the solution. 5.3.2 For alloys containing more than1% of silicon. Transfer the filter paper and residue to a plat
30、inum crucible using forceps, dry and ignite to burn off the paper. Allow to cool, add5ml of hydrofluoric acid 4)and five drops of nitric acid (sp.gr.1.42). When the reaction has subsided evaporate carefully to dryness (Note8.4), take up the residue in5ml of nitric acid (50%) and add to the main solu
31、tion. 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 (Note8.2) and record the values of per cent absorption or absorbance depending upon the instrument and type of read out. 6 Calibration 6.1 To a
32、 series of 100ml 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(1mlN 0.01mg of zinc or1mlN 0.1mg of zinc) as shown in the following table. 6.2 Dilute to the mar
33、k and mix. 6.3 Aspirate the solutions (Note8.2) 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 (see7. Calculation) against the
34、nominal zinc contents of the solutions. 3) Whatman No. 540 is suitable. 4) This refers to the usual analytical reagent grade of40% w/w. Zinc content Volumetric size flask % ml 0.005 0.05 100 0.05 0.20 500 Zinc content Aluminium solution Standard zinc solution 1 ml N 0.01 mg of zinc Corresponding zin
35、c in sample % ml ml mg 0.005 0.05 (Note 8.5) 25 0, 5, 10 0.00, 0.05, 0.10 Standard zinc solution 1 ml N N 0.1 mg of zinc ml 2, 3, 4, 5 0.20, 0.30, 0.40, 0.50 0.05 0.25 5 0, 1, 2, 3, 4, 5 0.00, 0.10, 0.20, 0.30, 0.40, 0.50BS1728-21:1973 BSI 12-1999 3 7 Calculation If the instrument reads per cent abs
36、orption 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 or drillings of99.99% purity aluminium should be used and these should be cleaned immediately before use with a little
37、 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 solutions and aspirated immediately after the calibration solutions and blank without altering the instrument settings. After t
38、he 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 altered (i.e.atomizer blocked, etc.). 8.3 For samples which are difficult to attack with hydrochloric acid add a drop of me
39、tallic mercury. 8.4 If necessary repeat the treatment with hydrofluoric and nitric acids. 8.5 For zinc contents between0.005and0.02% it is advisable to restrict the calibration curve to the first four dilutions, and then to use suitable scale expansion.4 blankBS1728-21:1973 BSI 12-1999 Publication r
40、eferred 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 usually associated with the words “approved to Br
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