1、BRITISH STANDARD BS 6721-5: 1986 ISO 4740:1985 Sampling and analysis of copper and copper alloys Part 5: Method for determination of zinc in copper and copper alloys by flame atomic absorption spectrophotometry ISO title: Copper and copper alloys Determination of zinc content Flame atomic absorption
2、 spectrometric method UDC 669.3:543.422.062:546.47BS6721-5:1986 This British Standard, having been prepared under the directionof the Non-ferrous Metals Standards Committee,waspublished underthe authorityof the BoardofBSI and comes into effect on 31December1986 BSI 12-1999 The following BSI referenc
3、es relate to the work on this standard: Committee reference NFM/34 Draft for comment 78/75336 DC ISBN 0 580 15298 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Non-ferrous Metals Standards Committee (NFM/-) to Technical Committee NFM
4、/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 drafting of th
5、e standard, through subcommittees and panels: BNF Metals Technology Centre British Bronze and Brass Ingot Manufacturers Copper Smelters and Refiners Association Ministry of Defence National Brassfoundry Association Coopted members Amendments issued since publication Amd. No. Date of issue CommentsBS
6、6721-5:1986 BSI 12-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling 1 7 Procedure 2 8 Expression of results 3 9 Test report 3 Table 1 2 Table 2 2 Table 3 2 Table 4
7、2 Publications referred to Inside back coverBS6721-5:1986 ii BSI 12-1999 National foreword This Part of BS 6721 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 al
8、loys. It is intended that Parts1 to3 of BS6721 will describe methods of sampling copper and 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 ISO4740:1985 “Copper and c
9、opper alloys Determination of zinc content Flame atomic absorption spectrometric method”, published 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 wit
10、hout deviation. Some terminology and certain conventions are not identical with those used in 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
11、 marker. Wherever the words “International Standard” appear, referring to this standard, they 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
12、sulfur, etc. Cross-reference. The Technical Committee has reviewed the provisions of ISO/R1811, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. ISO/R 1811 is under revision. It is expected that when published the revision wi
13、ll be implemented as a Part of BS6721. Textual errors. When adopting the text of the International Standard, the textual errors given below were discovered. They have been marked in the text and have been reported to ISO Central Secretariat in a proposal to amend the text of the International Standa
14、rd. In 4.4, line 3, “(3.3)” should be “(4.3)”. In 4.5, line 3, “(3.3)” should be “(4.3)”. In 4.6, line 3, “(3.4)” should be “(4.4)”. In Table 3, first column heading, “(3.4)” should be “(4.4)”. In Table 3, second column heading “(3.2)” should be “(4.2)”. A British Standard does not purport to includ
15、e 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 legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i
16、 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 incorporated. This will be indicated in the amendment table on the inside front cover.BS6721-5:1986 BSI 12-1999 1 1 Scope and field of application This Interna
17、tional Standard specifies a flame atomic absorption spectrometric method for the determination of the zinc content of all types of copper and copper alloys excluding copper alloys containing more than10% (m/m) of lead. The method is applicable to the determination of zinc contents between0,001and6%
18、(m/m). 2 Reference ISO/R 1811, Chemical analysis of copper and copper alloys Sampling of copper refinery shapes 1) . 3 Principle Dissolution of a test portion in fluoroboric-nitric acid, followed by aspiration into the air/acetylene flame of a flame atomic absorption spectrometer. Comparison of the
19、absorption of the resonance energy of zinc at213,8nm with those of standard matching solutions of zinc. 4 Reagents During the analysis, use only reagents of recognized analytical grade, and only distilled or deionized water. 4.1 Fluoroboric-nitric acid, attack solution. Mix together300ml of boric ac
20、id solution (40g/l), 30ml of hydrofluoric acid 40% (V/V), 500ml of nitric acid ( 1,40g/ml) and150ml of water. 4.2 Copper, base solution Weigh 10,0g of copper containing not more than0,0002% (m/m) zinc into a1000ml PTFE beaker. Add400ml of the attack solution (3.1) and warm until the copper is dissol
21、ved. Boil the solution until all brown fumes have been expelled. Cool and transfer the solution to a500ml one-mark volumetric flask. Dilute to the mark with water andmix. 50 ml of this solution contains1g of copper and40ml of attack solution (4.1). 4.3 Zinc, standard stock solution, corresponding to
22、5g of Zn per litre. Transfer 2,5 0,0001g of zinc metal (99,99% purity) to a 250ml tall-form beaker. Add50ml of nitric acid solution ( 1,40g/ml, diluted1+1), cover and heat gently until the metal is dissolved. Boil the solution for several minutes to expel nitrous fumes, then cool. Transfer the solut
23、ion to a500ml one-mark volumetric flask, dilute to the mark with water and mix. 1 ml of this standard solution contains5mg of Zn. 4.4 Zinc, standard solution, corresponding to0,5g of Zn per litre. Transfer100,0ml of the zinc standard solution(3.3) 2)to a1000ml one-mark volumetric flask. Dilute to th
24、e mark with water and mix. 1 ml of this standard solution contains0,5mg of Zn. 4.5 Zinc, standard solution, corresponding to0,05g of Zn per litre. Transfer 10,0 ml of the zinc standard stock solution(3.3) 2)to a1000ml one-mark volumetric flask. Dilute to the mark with water and mix. 1 ml of this sta
25、ndard solution contains0,05mg ofZn. 4.6 Zinc, standard solution, corresponding to0,01g of Zn per litre. Transfer 20,0 ml of the zinc standard solution (3.4) 2)to a 1000ml one-mark volumetric flask. Dilute to the mark with water and mix. 1 ml of this standard solution contains0,01mg ofZn. 5 Apparatus
26、 Ordinary laboratory apparatus, and 5.1 PTFE beakers, of capacity 250 ml. 5.2 Burette, graduated in 0,05 ml. 5.3 Flame atomic absorption spectrometer, including a light source emitting characteristic zinc spectral lines, for example a hollow-cathode or electrodeless discharge lamp. 5.4 Compressed ai
27、r supply 5.5 Cylinder of acetylene 6 Sampling Sampling shall be carried out in accordance with ISO/R1811. The sample should preferably be in the form of drillings with a maximum thickness of0,3mm. 1) Under revision 2) See national foreword for details of textual errors.BS6721-5:1986 2 BSI 12-1999 7
28、Procedure 7.1 Preparation of standard matching solutions 7.1.1 Zinc contents between 0,001 and 0,01% (m/m) Into a series of four 100ml one-mark volumetric flasks, introduce the volumes of the zinc standard solution (4.6) and base solution (4.2) shown in Table 1. Dilute to the mark with water and mix
29、. Table 1 7.1.2 Zinc contents between 0,005 and 0,06% (m/m) Into a series of six 200 ml one-mark volumetric flasks, introduce the volumes of the zinc standard solution (4.5) and base solution (4.2) shown in Table 2. Dilute to the mark with water and mix. Table 2 7.1.3 Zinc contents between 0,05 and
30、0,60% (m/m) Into a series of six 200 ml one-mark volumetric flasks, introduce the volumes of the zinc standard solution (4.4) and base solution (4.2) shown in Table 3. Dilute to the mark with water and mix. Transfer100,0ml of these solutions to each of six1000ml one-mark volumetric flasks, dilute to
31、 the mark and mix. Table 3 7.1.4 Zinc contents between 0,5 and 6% (m/m) Into a series of six 200 ml one-mark volumetric flasks, introduce the volumes of the zinc standard stock solution (4.3) and base solution (4.2) shown inTable 4. Dilute to the mark with water and mix. Transfer10,0ml of these solu
32、tions to each of six1000ml one-mark volumetric flasks, dilute to the mark and mix. Table 4 7.2 Preparation of test solution 7.2.1 Transfer a test portion of1 0,0002g to a PTFE beaker (5.1). If heating is carried out in a water bath, polypropylene or low-density polyethylene beakers may be used. 7.2.
33、2 Add 40 ml of the attack solution (4.1), cover, and warm gently until the test portion is dissolved, then heat at about90 C until nitrous fumes have been expelled. Wash down the cover and sides of the beaker and cool. 7.2.3 For zinc contents between0,001 and0,01% (m/m), transfer the solution (7.2.2
34、) quantitatively to a100ml one-mark volumetric flask, dilute to the mark and mix. 7.2.4 For zinc contents between0,005 and0,06% (m/m), transfer the solution (7.2.2) quantitatively to a200ml one-mark volumetric flask, dilute to the mark and mix. Volume of zinc standard solution (4.6) Volume of copper
35、 base solution (4.2) Mass of zinc per100 ml after dilution ml ml mg 0 a 1 5 10 50 50 50 50 0 0,01 0,05 0,10 a Blank test on reagents for calibration. Volume of zinc standard solution (4.5) Volume of copper base solution (4.2) Mass of zinc per100 ml after dilution ml ml mg 0 a 1 2 4 8 12 50 50 50 50
36、50 50 0 0,025 0,050 0,10 0,20 0,30 a Blank test on reagents for calibration. Volume of zinc standard solution (3.4) a Volume of copper base solution (3.2) a Mass of zinc per100 ml after final dilution ml ml mg 0 b 1 2 4 8 12 50 50 50 50 50 50 0 0,025 0,05 0,10 0,20 0,30 a See national foreword for d
37、etails of textual errors. b Blank test on reagents for calibration. Volume of zinc standard stock solution (4.3) Volume of copper base solution (4.2) Mass of zinc per100 ml after final dilution ml ml mg 0 a 1 2 4 8 12 50 50 50 50 50 50 0 0,025 0,05 0,10 0,20 0,30 a Blank test on reagents for calibra
38、tion.BS6721-5:1986 BSI 12-1999 3 7.2.5 For zinc contents between0,05 and0,60% (m/m), transfer the solution (7.2.2) quantitatively to a200ml one-mark volumetric flask, dilute to the mark and mix. Transfer100ml of this solution to a1000ml one-mark volumetric flask. Dilute to the mark and mix. 7.2.6 Fo
39、r zinc contents between0,50 and6% (m/m), transfer the solution (7.2.2) quantitatively to a200ml one-mark volumetric flask, dilute to the mark and mix. Transfer10,0ml of this solution to a1000ml one-mark volumetric flask. Dilute to the mark and mix. 7.3 Spectrometric measurements 7.3.1 Preparation of
40、 apparatus 3) Turn on the electric system and allow it to warm up. Adjust the zinc hollow-cathode lamp and set the wavelength drum to213,8nm. Regulate the air/acetylene flame. 7.3.2 Measurement of standard matching solutions Transfer portions of the standard matching solutions to small beakers and a
41、tomize into the flame. Take care to maintain a constant rate of aspiration over the full range of standard matching solutions. Record the absorbance of each standard matching solution. After each aspiration of a standard matching solution, atomize a small amount of water to clean the burner. Signal
42、amplification may be necessary for the series of standard matching solutions having the lowest concentration of zinc (7.1.1). 7.3.3 Plotting of calibration curves Using the measurements from 7.3.2, plot calibration curves with the zinc concentrations (mg/100ml) on the abscissa and corresponding abso
43、rbance values on the ordinate axis, subtracting the blank value from each standard value. NOTERecent work has demonstrated that calibration graphs may suffer from excessive curvature. A non-acceptable curvature would result when the mid-point calibration absorbance exceeds0,55times the absorbance of
44、 the maximum calibration solution. If this situation is encountered, the calibration solutions(7.1) should be diluted to the minimum standard volume needed to attain the curvature criterion stated. The test solutions (7.2) should also be diluted in the same proportion. 7.3.4 Measurement of test solu
45、tion Measure the absorbances of the test solution and blank in the same manner as the standard matching solutions (7.3.2). Bracket the test solution by two appropriate standard matching solutions. Carry out all measurements consecutively and without interruption in order to minimize instrumental flu
46、ctuations. 7.4 Blank test Carry out a blank test at the same time as the determination and following the same procedure, using the same quantities of reagents and of pure copper as for the determination but omitting the test portion. 7.5 Check test Make a preliminary check of the apparatus by prepar
47、ing a solution of standard material or a synthetic sample containing a known amount of zinc and of composition similar to the material to be analysed, and carrying out the procedure as specified in7.2 and 7.3. 8 Expression of results Using the appropriate calibration curve (7.3.3), determine the amo
48、unt of zinc in the test solution corresponding to the measured absorbance. Calculate the zinc content, as a percentage by mass, according to the formula where m 0 is the mass, in grams, of the test portion (1 g); m 1 is the mass, in milligrams, of zinc found in the blank test solution; m 2 is the ma
49、ss, in milligrams, of zinc found in the test solution; f is the ratio between the volume of the first flask, in millilitres, and the volume, in millilitres, transfered to the second flask; f = 1 when the first flask contains the final test solution, i.e., if no successive dilution is made. V is the volume, in millilitres, of the flask containing the final test solution. 9 Test report The test report shall include the following particulars: a) an identification of the sample; b) the reference of the method used; c) the results and the method of expression used;
