1、BRITISH STANDARD BS 1728-19: 1971 Method for The determination of magnesium in aluminium and aluminium alloys (Atomic absorption method) Methods for the analysis of aluminium and aluminium alloysBS1728-19:1971 This British Standard, having beenapproved by the Non-ferrous Metals Industry Standards Co
2、mmittee, was published under the authority ofthe Executive Board on 30July1971 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference NFE/-/3 Draft for comment 69/22087 ISBN 580 06604 5 Co-operating organizations The Non-ferrous Metals Industry Standards Co
3、mmittee, under whose 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 Association of Consulting Engineers Board of Trade Br
4、itish Bronze and Brass Ingot Manufacturers Association 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 Associa
5、tion* Copper Development Association Crown Agents for Oversea Governments and Administrations Electric Cable Makers Confederation Institute of British Foundrymen Institute of Metals Institution of Mechanical Engineers (Automobile Division) Institution of Mining and Metallurgy Institution of Producti
6、on 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 Defence, Navy Department* National Brassfoundry Association Non-ferrous Metal Stockists P
7、ost Office Royal Institute of British Architects Society of Motor Manufacturers and Traders Ltd. Tin Research Institute Zinc Development Association Individual manufacturers The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together wit
8、h 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. Ministry of Technology Laboratory of the Government Chemist Individual analysts Amendments issued since publication Amd. No.
9、Date CommentsBS1728-19:1971 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 1 5 Procedure 2 6 Calibration 3 7 Calculation 3 8 Notes 3BS1728-19:1971 ii BSI 12-1999 Foreword This standard makes refer
10、ence to the following British Standard: BS 1499, Sampling non-ferrous metals. This method for the determination of magnesium is the nineteenth 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 p
11、ublished as a separate part. Other methods in the series are as follows: Part 1: Copper; Part 2: Magnesium; Part 3: Zinc (mercuric potassium thiocyanate method); Part 5: Copper (absorptiometric method); Part 6: Iron (volumetric: titanous chloride method); Part 8: Iron (absorptiometric 1 : 10 phenant
12、hroline method); Part 9: Manganese (volumetric arsenite/nitrite 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 (g
13、ravimetric method); Part 15: Nickel (photometric method); Part 16: Chromium (photometric method); Part 17: Chromium (volumetric method); Part 18: Zinc (ion-exchange volumetric EDTA or polarographic method); Part 20: Lead (atomic absorption method). The preparation of this series of methods has been
14、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 instances they may appear
15、to be lengthy, it should be appreciated that they are primarily intended as “referee” methods to be used in cases of dispute. 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. Complianc
16、e with a British 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, pages1 to 3 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporat
17、ed. This will be indicated in the amendment table on the inside front cover.BS1728-19:1971 BSI 12-1999 1 1 Introduction 1.1 Principle. The sample is dissolved in hydrochloric and perchloric acids, an appropriate aliquot is taken, lanthanum chloride solution is added and the magnesium content is dete
18、rmined by atomic absorption spectrophotometry. 1.2 Range. The method is recommended for magnesium contents between0.01and6%. 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 by
19、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. 2.2 Any atomic absorption spectrophotometer with adequate sensitivity and precision and preferably attached to a chart recorder read
20、out or integrating device and capable of measuring absorption at a wavelength of285.2nm. 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%. 3 Solutions required All reagents shall be of the highest
21、 purity obtainable, and distilled or de-mineralized water shall be used throughout. Standard magnesium (1 ml N 1mg of magnesium). Dissolve1.0g of high purity magnesium in30ml of hydrochloric acid (50%). Transfer to a1litre volumetric flask, dilute to the mark and mix. Standard magnesium (1 ml N 504g
22、 of magnesium). Transfer50ml of standard magnesium solution(1ml=1mg of magnesium) to a1litre volumetric flask, dilute to the mark and mix. This solution should be freshly prepared. Hydrochloric acid (50% v/v). Dilute500ml of hydrochloric acid (sp. gr. 1.16 1.18) to1litre and mix. Lanthanum chloride.
23、 Dissolve cautiously120g of lanthanum oxide (La 2 O 3 ,99.9% pure) in200ml of water and500ml of hydrochloric acid (sp. gr. 1.16 1.18). Dilute to1litre and mix. Store in a polythene bottle. Nickel chloride. Dissolve0.1g of nickel in10ml of hydrochloric acid (50%). dilute to100ml and mix. 4 Sampling R
24、ecommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS 1499, “Sampling non-ferrous metals”. Magnesium content Standard deviation % 0.08 0.18 0.71 1.0 2.7 4.3 0.0036 0.0058 0.020 0.028 0.026 0.035BS1728-19:1971 2 BSI 12-1999 5 Procedure NOTEAlth
25、ough the use of perchloric acid as described in this method has not been found hazardous, attention is drawn to the well-known danger of explosions which can arise if it is brought in contact under certain conditions with finely divided aluminium, silicon and organic matter (for instance, alcohol va
26、pour). 5.1 Adjust the weight of sample as follows: 5.2 Transfer the appropriate weight of sample to a250ml beaker. (Note 8.1.) Add10ml of hydrochloric acid (sp. gr. 1.16 1.18) and10ml of water. If necessary heat to assist dissolution. 5.3 Carry out simultaneously a blank determination following the
27、same procedure and using the same amounts of reagents as with the sample. 5.4 Allow to cool and add10ml of perchloric acid (sp. gr. 1.70). Heat until strong fumes of perchloric acid appear and allow to cool. Redissolve the salts in25ml of water, heating if necessary. 5.5 Transfer the solution to the
28、 appropriate size volumetric flask indicated in the table below, filter if necessary through a close textured filter paper 1) , wash the precipitate four times with water and add the washings to the sample solution. 5.5.1 For alloys containing up to1% of silicon. Discard any filter paper and residue
29、. 5.5.1.1 For magnesium contents from 0.01up to 0.05%. Use the whole of the solution. 5.5.1.2 For magnesium contents over 0.05 up to 6%. Dilute to the mark and mix. Then transfer the appropriate aliquot to a250ml volumetric flask (see table above). 5.5.2 For alloys containing more than1% of silicon.
30、 Transfer the filter paper and residue to a platinum crucible using forceps, dry and ignite to burn off paper. Allow to cool, add5ml of hydrofluoricacid 2)and five drops of nitric acid (sp. gr. 1.42). When the reaction has subsided evaporatecarefully to dryness (Note 8.2). Take up the residue in a l
31、ittle water and a few drops of hydrochloric acid (sp. gr. 1.16 1.18). 5.5.2.1 For magnesium contents from 0.01 up to 0.05%. Add to the main solution in the250ml volumetric flask. 5.5.2.2 For magnesium contents over 0.05 up to6%. Add to the main solution in the volumetric flask of the appropriate siz
32、e, dilute to the mark and mix. Then transfer the appropriate aliquot to a250ml volumetric flask (see table above). 5.6 Add the appropriate quantity of the lanthanum chloride solution. Dilute to the mark and mix. 5.7 Aspirate the solution (Note 8.1) and record the values of per cent absorption or abs
33、orbance depending upon the instrument and type of read out. Magnesium content Sample weight % g 0.01 to 2 2to 6 0.50 0.25 1) Whatman No. 540 is suitable. Magnesium content Volumetric flask size Aliquot Lanthanum chloride solution % ml ml ml 0.01 to 0.05 0.05 to 0.25 0.25 to 0.5 0.5to 2 2to 6 250 100
34、 100 500 500 whole 20 10 10 10 50 10 10 10 5 2) This refers to the usual analytical reagent grade of 40% w/w.BS1728-19:1971 BSI 12-1999 3 6 Calibration 6.1 To a series of250ml beakers transfer a weight of aluminium (99.99% pure) corresponding to the sample weight and continue as in 5.1 to 5.4 of the
35、 procedure, adding a few drops of the nickel chloride solution to assist solution of the aluminium. 6.2 Transfer the solutions to a series of volumetric flasks of the appropriate size (see table below). 6.2.1 For magnesium contents from0.01up to0.05%. Use the whole of each solution. 6.2.2 For magnes
36、ium contents over0.05up to6%. Dilute to the mark and mix, then transfer the appropriate aliquots to a series of250ml volumetric flasks. 6.3 Add to each the appropriate quantity of lanthanum chloride solution (see table above) then add respectively the quantities of standard magnesium solution (1ml =
37、54g of magnesium) shown in the above table. Dilute to the mark and mix (Note 8.3). 6.4 Aspirate the solutions (Note 8.1) and record the values of per cent absorption or absorbance depending upon the instrument and type of read out. 6.5 Deduct the absorbance reading for the blank and prepare a calibr
38、ation graph by plotting absorbance values (see 7 Calculation) against the nominal magnesium contents of the solutions. 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 magnesium
39、by means of the calibration graph. 8 Notes 8.1 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 instrument settings. 8.2 If necessary repeat the treatment with hydrofluor
40、ic and nitric acids. 8.3 The concentration ranges and dilutions specified have been found suitable for the determination of magnesium with certain instruments. They are therefore given as a guide but may have to be modified to suit individual instruments. Magnesium content Volumetric flask size Aliq
41、uot Standard magnesium solution 1 ml = 50 4g of magnesium Lanthanum chloride solution % ml ml ml ml 0.01 to 0.05 0.05 to 0.25 0.25 to 0.5 0.5to 2 2to 6 250 100 100 500 500 whole 20 10 10 10 0, 1, 2, 3, 4, 5, 6 0, 1, 2, 3, 4, 5 0, 1, 2, 3, 4, 5 0, 0.5, 1, 2, 3, 4, 5 0, 1, 2, 3, 4, 5, 6 50 10 10 10 5B
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