1、BRITISH STANDARD BS 6075-3: 1981 ISO 983:1974 Methods of Sampling and test for sodium hydroxide for industrial use Part 3: Determination of iron content ISO title: Sodium hydroxide for industrial use Determination of iron content 1,10-Phenanthroline photometric method NOTEIt is recommended that this
2、 Part be read in conjunction with the information in the “Generalintroduction”, published separately as BS6075-0. UDC 661.322.1:546.33 36:543.42.062:546.72BS6075-3:1981 This British Standard, having been prepared under the directionof the Chemicals Standards Committee, was published under the author
3、ityofthe Executive Boardand comes into effect on 27February1981 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference CIC/22 Draft for comment 73/54863 DC ISBN 0 580 12053 8 Amendments issued since publication Amd. No. Date of issue CommentsBS6075-3:1981 B
4、SI 10-1999 i Contents Page National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Procedure 1 7 Expression of results 2 8 Test report 2 Publications referred to Inside back coverBS6075-3:1981 ii BSI 10-1999 National foreword This Part of BS60
5、75is identical with ISO983“Sodium hydroxide for industrial use Determination of iron content 1,10-Phenanthroline photometric method”, published in 1974 by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved a
6、s suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the following. The comma has been used throughout as a decimal marker. In British Standards it is curr
7、ent practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. Additional information Water. Water complying with the requirements of clause 4 is specified in BS 3978 “
8、Water for laboratory use”. Hydrochloric acid, approximately1.18g/ml, which is the corresponding reagent normally obtainable in the UK, is suitable for use in place of the solution specified in 4.1. Test portion. For some grades of sodium hydroxide it may be necessary to adjust the mass of the test p
9、ortion (see 6.1) to ensure that the amount of iron present in the test solution complies with the requirements for the test method. In BS4130“Sodium hydroxide (technical grades)” details of a suitable mass for the solid grades specified are given. WARNING. Hydroxylammonium chloride, specified in 4.3
10、, is toxic, corrosive and irritant. Avoid contact with eyes and skin. 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 immu
11、nity from legal obligations. Cross-reference International Standard Corresponding British Standard BS 6075 Methods of sampling and test for sodium hydroxide for industrial use ISO 3195:1975 Part 5:1981 Sampling and preparation of main test solution (Identical) Summary of pages This document comprise
12、s a front cover, an inside front cover, pages i and ii, pages1 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 amendment table on the inside front cover.BS6075-3:1981 BSI 10-1999
13、 1 1 Scope and field of application This International Standard specifies a 1,10-phenanthroline photometric method for the determination of the iron content of sodium hydroxide for industrial use. This method is more sensitive and more widely used than the 2,2-bipyridyl method which was specified in
14、 ISO/R 983:1969. The method is applicable to products having iron contents equal to or greater than0,5mg/kg. 2 Reference ISO 3195, Sodium hydroxide for industrial use Sampling Test sample Preparation of the main solution for carrying out certain determinations 1) . 3 Principle Reduction of the triva
15、lent iron by hydroxylammonium chloride, followed by the formation of a bivalent iron/1,10-phenanthroline complex in a buffered system. Photometric measurement of the coloured complex at a wavelength of about510nm. 4 Reagents During the analysis, use only reagents of recognized analytical reagent gra
16、de, and only distilled water, or water of equivalent purity. 4.1 Hydrochloric acid, approximately1,19g/ml, about38% (m/m) solution or approximately12N. 4.2 Ammonia solution, approximately0,91g/ml, about25% (m/m) NH 3solution or approximately13N, with a maximum iron content of0,2mg/kg. 4.3 Hydroxylam
17、monium chloride (NH 2 OH.HCl),10g/l solution. 4.4 Buffer solution, pH 4,9. Dissolve272g of sodium acetate trihydrate (CH 3 COONa.3H 2 O) in about500ml of water. Add240ml of glacial acetic acid ( approximately1,05g/ml,99to100% (m/m) solution or approximately17,4 N) to the solution, dilute to1000ml an
18、d mix. 4.5 Bromine water, saturated at room temperature. 4.6 1,10-phenanthroline hydrochloride monohydrate (C 12 H 8 N 2 .HCl.H 2 O), 2,5 g/l solution. This reagent may be replaced by 1,10-phenanthroline monohydrate (C 12 H 8 N 2 .H 2 O), 2,5 g/l solution. 4.7 Iron, standard solution, corresponding
19、to0,200g of Fe per litre. Dissolve1,404 3g of ammonium iron(II) sulphate hexahydrate (NH 4 ) 2 Fe(SO 4 ) 2 .6H 2 O, weighed to the nearest0,0001 g, in200 mlof water. Add20 ml of sulphuric acid, approximately1,84g/ml, cool to room temperature, dilute to the mark ina1000mlone-mark volumetric flask and
20、 mix. 4.8 Iron, standard solution corresponding to0,010g of Fe per litre. Transfer25,0ml of the standard iron solution (4.7) to a500ml one-mark volumetric flask, dilute to the mark and mix. Prepare this solution immediately before use. 1 ml of this standard solution contains0,010mg ofFe. 4.9 Methyl
21、orange, 0,5g/l solution. 5 Apparatus Ordinary laboratory apparatus and 5.1 Spectrophotometer, or 5.2 Photoelectric absorptiometer, fitted with filters giving a maximum transmission between500and520nm. 6 Procedure 6.1 Test portion Weigh, to the nearest0,01g, in a weighing bottle fitted with a ground
22、glass lid, a mass of the test sample, 2)solid or liquid, containing between25and30g of NaOH. 6.2 Blank test Pour25ml of water and a volume of the hydrochloric acid solution (4.1) identical to that used to neutralize the test portion (see 6.4.1) into a600ml beaker. Add40ml of the ammonia solution(4.2
23、) and5drops of the methyl orange solution (4.9) and then neutralize with the ammonia solution (4.2). Add the hydrochloric acid solution(4.1), drop by drop, until the colour changes to red, and then an excess of2ml of this acid. Add5ml of the bromine water (4.5) to remove the colour of the indicator,
24、 boil for5min, cool to room temperature, transfer the solution quantitatively to a250ml one-mark volumetric flask, dilute to the mark and mix. Proceed as described in 6.4.2. 1) At present at the stage of draft. 2) See ISO 3195.BS6075-3:1981 2 BSI 10-1999 6.3 Preparation of the calibration curve 6.3.
25、1 Preparation of the standard colorimetric solutions, for photometric measurements with a5cm cell. Into a series of five100ml one-mark volumetric flasks, transfer the quantities of the standard iron solution (4.8) indicated in the following table: Add0,5ml of the hydrochloric acid solution (4.1) and
26、 the amount of water necessary to make up the volume to about50ml to each flask. Then add5ml of the hydroxylammonium chloride solution(4.3),5ml of the 1,10-phenanthroline hydrochloride solution (4.6) and25ml of the buffer solution (4.4). Dilute to the mark, mix and wait for10min. 6.3.2 Photometric m
27、easurements Carry out the photometric measurements with the spectrophotometer (5.1), at a wavelength of about510nm, or with the photoelectric absorptiometer (5.2), fitted with suitable filters, after having adjusted, in each case, the instrument to zero absorbance against the compensation solution.
28、6.3.3 Plotting the calibration curve Prepare a chart having, for example, the iron (Fe) contents in milligrams per100ml of the standard colorimetric solutions as abscissae and the corresponding values of absorbance as ordinates. 6.4 Determination 6.4.1 Preparation of the test solution Transfer the t
29、est portion (6.1) to a1000 ml beaker. Add120ml of water, and neutralize cautiously with the hydrochloric acid solution (4.1) in the presence of5drops of the methyl orange solution (4.9). Add an excess of2ml of this acid, followed by5ml of the bromine water (4.5). Boil for5min, cool to room temperatu
30、re, transfer quantitatively to a250ml one-mark volumetric flask, dilute to the mark andmix. 6.4.2 Colour development Transfer50,0ml of the test solution (6.4.1) to a100ml one-mark volumetric flask. Add5ml of the hydroxylammonium chloride solution (4.3),5ml of the1,10-phenanthroline hydrochloride sol
31、ution(4.6) and25ml of the buffer solution (4.4). Dilute to the mark, mix and wait for10min. 6.4.3 Photometric measurement Measure the absorbance of the solution (6.4.2), as described in 6.3.2, after having adjusted the instrument to zero absorbance against the blank test solution (6.2). 7 Expression
32、 of results By reference to the calibration curve (6.3), determine the quantity of Fe corresponding to the value of the absorbance measured. The iron content, expressed as milligrams of iron(Fe) per kilogram, is given by the formula where 8 Test report The test report shall include the following par
33、ticulars: a) the reference of the method used; b) the results and the method of expression used; c) any unusual features noted during the determination; d) any operation not included in this International Standard or the International Standard to which reference is made, or regarded as optional. Sta
34、ndard iron solution(4.8) Corresponding mass of Fe ml mg 0 a 0 2,5 0,025 5,0 0,050 10,0 0,100 15,0 0,150 a Compensation solution m 0 is the mass, in grams, of the test portion; m 1 is the mass, in milligrams, of Fe found in the aliquot portion of the test solution.BS6075-3:1981 BSI 10-1999 Publicatio
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