1、BRITISH STANDARD BS 6075-12: 1981 Methods of Sampling and test for sodium hydroxide for industrial use Part 12: Determination of copper content NOTEIt is recommended that this Part be read in conjunction with the information in the “Generalintroduction” published separately as BS 6075-0. UDC 661.322
2、.1:546.3336:543.42.062:546.56BS6075-12:1981 This British Standard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authority ofthe Executive Board and comesinto effect on 27February1981 BSI 11-1999 The following BSI reference relates to the work
3、on this standard: Committee reference CIC/22 ISBN 0 580 12062 7 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 f
4、rom legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 and 2, 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 amen
5、dment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS6075-12:1981 BSI 11-1999 i Contents Page 1 Scope 1 2 References 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Procedure 1 7 Expression of results 2 Table 1 Volumes of standard copper solution 1
6、 Publications referred to Inside back coverii blankBS6075-12:1981 BSI 11-1999 1 1 Scope This Part of BS 6075 describes a method of test for the determination of the copper content of sodium hydroxide for industrial use. The method is applicable to products having copper contents, expressed as Cu, in
7、 the ranges 0.5 mg/kg to 10 mg/kg and 0.25 mg/kg to 5 mg/kg for the solid and liquid products, respectively. There is no corresponding International Standard for this method. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Principle The
8、 copper present is reduced with ascorbic acid and a violet coloured complex is formed by addition of 2,2-biquinolyl. This complex is extracted with amyl alcohol and its colour measured spectrophotometrically. 4 Reagents The reagents used shall be of recognized analytical quality. Water complying wit
9、h the requirements of BS 3978 shall be used throughout. 4.1 Sodium hydroxide 4.2 Sodium sulphate, anhydrous. 4.3 Hydrochloric acid solution, approximately1.18g/ml, approximately 36% (m/m) solution or approximately 11N. 4.4 Amyl alcohol 4.5 (+)Tartaric acid, 500 g/l solution. 4.6 Sodium hydroxide, 20
10、0 g/l solution. 4.7 L-Ascorbic acid, 100 g/l solution, freshly prepared. 4.8 2,2-Biquinolyl, 0.5 g/l solution. Dissolve 0.25 g of 2,2-biquinolyl in the amyl alcohol (4.4) and dilute with more of the amyl alcohol to 500 ml. 4.9 Bromine water, saturated solution. 4.10 Copper, standard solution corresp
11、onding to0.1g of copper per litre. Dissolve 0.3928 g of copper (II) sulphate pentahydrate (CuSO 4 .5H 2 O) in water in a 1000 ml one-mark volumetric flask, add25 ml of approximately 6N sulphuric acid solution, dilute to the mark and mix. 1 ml of this standard solution contains 0.100 mg ofCu. 4.11 Co
12、pper, standard solution corresponding to0.01 g of copper per litre. Dilute 10.0 ml of the standard copper solution (4.10) to the mark in a100ml one-mark volumetric flask and mix. 1 ml of this standard solution contains 10 4g of Cu. 4.12 Narrow range indicator papers, covering the range pH 5.5 to pH
13、7.0. 4.13 Methyl orange indicator, 0.5 g/l aqueous solution. 5 Apparatus Ordinary laboratory apparatus and the following are required. 5.1 Spectrophotometer, or 5.2 Photoelectric absorptiometer, fitted with filters providing maximum transmission at a wavelength of about 545 nm. 5.3 Optical cells, 4
14、cm optical path length. 6 Procedure 6.1 Test portion. Weigh, to the nearest 0.01 g in a plastics weighing bottle fitted with a cover, an amount of the sample corresponding to about 10 g of sodium hydroxide. 6.2 Blank test. Carry out a blank test at the same time as the determination, following the s
15、ame procedure and using the same quantities of reagents as specified in 6.4 but using 10 g of the sodium hydroxide (4.1). 6.3 Preparation of the calibration graph 6.3.1 Preparation of standard matching solutions. Into each of a series of six 500 ml stoppered separating funnels, introduce the volumes
16、 of the standard copper solution (4.11) shown in Table 1. Table 1 Volumes of standard copper solution Standard copper solution(4.11) Corresponding mass of copper (Cu) ml 4g 0 a 2.0 4.0 6.0 8.0 10.0 0 20 40 60 80 100 a Compensation solution.BS6075-12:1981 2 BSI 11-1999 6.3.2 Colour development. Treat
17、 the contents of each funnel (6.3.1) as follows. Dilute with water to approximately 400 ml, then add 2 ml of the tartaric acid solution (4.5). Adjust the pH of the solution to about 6.0 by addition of the sodium hydroxide solution (4.6) using the narrow range indicator paper (4.12) externally. Add 2
18、 ml of the ascorbic acid solution (4.7), shake so as to mix thoroughly and allow to stand for5min. Add 10 ml of the 2,2-biquinolyl solution(4.8) and shake well for about 2 min. Extract the copper complex with two 20 ml portions of the amyl alcohol (4.4), and transfer the extracts to a 100 ml beaker.
19、 Add about 2 g of the anhydrous sodium sulphate (4.2) to the combined extracts and stir thoroughly to remove traces of water. Filter the dried extract into a50ml one-mark volumetric flask, wash the residual sodium sulphate twice with 2 ml portions of the amyl alcohol (4.4). Transfer the washings to
20、the flask, dilute to the mark with the amyl alcohol(4.4) and mix. 6.3.3 Photometric measurements. Carry out the photometric measurements either with the spectrophotometer (5.1) at the wavelength of maximum absorption (about 545 nm), or with the photoelectric absorptiometer (5.2), fitted with suitabl
21、e filters, after having adjusted the instrument to zero absorbance against the amyl alcohol (4.4). 6.3.4 Plotting the calibration graph. Deduct the absorbance of the compensation solution (6.3.1) from those of the standard matching solutions(6.3.1). Plot a graph having, for example, the copper conte
22、nt expressed in micrograms per50ml of standard matching solution, as abscissae and the corresponding values of absorbance as ordinates. 6.4 Determination 6.4.1 Preparation of the test solution. Transfer the test portion quantitatively to a 400 ml beaker. Add about 100 ml of water and 1 drop of the m
23、ethyl orange indicator solution (4.13). Neutralize the solution with the hydrochloric acid solution (4.3), then add 5 ml in excess and add 10 ml of the bromine water (4.9). Boil the solution until free from bromine and allow to cool. Transfer the contents of the beaker quantitatively to a 500 ml sep
24、arating funnel fitted with a stopper. 6.4.2 Colour development. Treat the test solution in the separating funnel (6.4.1) as specified in 6.3.2. 6.4.3 Photometric measurement. Carry out the photometric measurement on the test solution(6.4.2) and on the blank test solution (6.2) following the procedur
25、e described in 6.3.3, after having adjusted the instrument to zero absorbance against the amyl alcohol (4.4). NOTEIf the absorbance exceeds the maximum of the calibration graph, repeat the determination using a smaller amount of the test portion (6.1) and modifying the calculation accordingly. 7 Exp
26、ression of results By means of the calibration graph (6.3.4), determine the quantity of copper (Cu) corresponding to the value of the photometric measurement. The copper content, expressed as milligrams of copper (Cu) per kilogram, is given by the following formula: where m 0 is the mass of the test
27、 portion (in g) m 1 is the mass of copper in the test solution (in4g) m 2 is the mass of copper in the blank test solution (in 4g) m 1 m 2 1000 - 1000 m 0 - m 1 m 2 () m 0 - = BS6075-12:1981 BSI 11-1999 Publications referred to BS 1647, pH scale. BS 3978, Water for laboratory use. BS 6075-12: 1981 B
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