1、BRITISH STANDARD CONFIRMED JUNE 1993 BS6337-3: 1983 ISO6685:1982 General methods of chemical analysis Part3: Method for determination of iron content(1,10-phenanthroline spectrophotometric method) ISO title: Chemical products for industrial use General method for determination of iron content 1,10-p
2、henanthroline spectrophotometric method UDC543.422.062:546.72BS6337-3:1983 This British Standard, having been prepared under the directionof the Chemical Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 31January1983 BSI12-1999 The following BSI refer
3、ences relate to the work on this standard: Committee reference CIC/- Draft for comment79/55087 DC ISBN 0 580 13152 1 Cooperating organizations The Chemical Standards Committee, under whose direction this BritishStandard was prepared, consists of representatives from the following: Association of Fat
4、ty Acid Distillers British Tar Industry Association Chemical Industries Association* Consumer Standards Advisory Committee of BSI Department of Health and Social Security Department of Industry (Laboratory of the Government Chemist) Fertiliser Manufacturers Association Ltd. Ministry of Agriculture,
5、Fisheries and Food Ministry of Defence* National Sulphuric Acid Association Paintmakers Association of Great Britain Ltd. Royal Institute of Public Health and Hygiene Royal Society of Chemistry Soap and Detergent Industry Association Standardization of Tar Products Tests Committee The organizations
6、marked with an asterisk in the above list, together with coopted members nominated by other BSI committees, were directly represented on the Technical Committee entrusted with the preparation of this British Standard. Amendments issued since publication Amd. No. Date of issue CommentsBS6337-3:1983 B
7、SI 12-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii 1 Scope 1 2 Field of application 1 3 Principle 1 4 Reagents 1 5 Apparatus 2 6 Procedure 2 7 Expression of results 2 8 Test report 3 Annex Interferences 4 Table 1 3 Table 2 3BS6337-3:1983 ii BSI 12-1999 Natio
8、nal foreword This Part of BS6337 is the third of a series of general methods of chemical analysis prepared under the direction of the Chemical Standards Committee. It is identical with ISO6685:1980 “Chemical products for industrial use General method for determination of iron content-1,10-phenanthro
9、line spectrophotometric method”, published by the International Organization for Standardization (ISO). For some years, the UK has participated in the work of Subcommittee1 General methods, of Technical Committee47 Chemistry, of ISO. As international agreement is reached on the methods, it is propos
10、ed to publish them as Parts of this British Standard. The work of Subcommittee1 on such general methods was motivated by the existence of a multiplicity of methods for the same determination, all differing to various degrees, that had been prepared by the ISO/TC47 sub-committees, etc., responsible f
11、or particular chemical products or groups of products. For this historical reason, unnecessary proliferation of different reagents, apparatus and procedures had been developed. These general methods are intended to reduce such proliferation, as far as is possible. They assume that a suitable test so
12、lution of a product to be analyzed hasbeen prepared, by a method established in the standard relating to the product concerned, which also gives other specific details such as relevant interfering species and how to overcome them, and how the results should be expressed. It is hoped and expected tha
13、t any committees that wish to revise existing, or prepare new, standards involving an analysis corresponding to the general methods, will do so by no more than cross-references to the appropriate parts of this British Standard. Because a general method cannot take into account the properties of all
14、the products to which it may be applied, it should indicate what characteristics the test solution should have in order that the method can be applied to it. The compiler of the product standard should indicate how the test portion is to be treated in order to obtain a test solution with the require
15、d characteristics. Moreover, while a general method should include a list of known interferences, together with suggestions by which they can be overcome, the product standard should indicate what interferences might be expected in a particular product and what action should be taken if they are pre
16、sent so that the general method can be applied to the product concerned. Because no product standard can be expected to foresee all eventualities, the user of the product standard should check in all cases that the general method will be applicable to a particular material. This method was developed
17、 on behalf of ISO by the Analytical Methods Committee of the Analytical Division of the Royal Society of Chemistry (formerly the Society for Analytical Chemistry), and the British Standards Institution wishes to acknowledge its appreciation of this contribution to national and international standard
18、ization. Terminology and conventions. The text of the International Standard has been approved as 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 fo
19、llowing. 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 marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. Additional informati
20、on. In5.1 and6.3.1, the comma between “1” and “2” is not a decimal comma. In6.4.1, it is not clear that the aliquot portion of the test solution that is taken can be less than60ml in volume. This would be clearer if the words “not more than” were inserted before“60ml” in line2.BS6337-3:1983 BSI 12-1
21、999 iii 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 from legal obligations. Summary of pages This document co
22、mprises a front cover, an inside front cover, pagesi to iv, pages1to5 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.iv blankBS6337-3:1983 BSI 12-1999 1 1 Scope Th
23、is International Standard specifies a general1,10-phenanthroline spectrophotometric method for the determination of the iron content of chemical products for industrial use. It describes a technique for the determination of the content of iron in a solution. Reference should be made, for the prepara
24、tion of the test solution, to the International Standard relating to the product to be analysed, which should indicate the modifications necessary to make the method applicable to that product. 2 Field of application The method is applicable to test solutions from which an aliquot portion can be tak
25、en containing between10 and5004g of Fe in a volume of not more than60ml. Large amounts of alkali metals, calcium, strontium, barium, magnesium, manganese(II), arsenic(III), arsenic(V), uranium(VI), lead, chloride, bromide, iodide, thiocyanate, acetate, chlorate, nitrate, sulphate, sulphide, metabora
26、te, selenate, citrate, tartrate, phosphate and up to100mg of germanium(IV), in the test solution, do not interfere. In the presence of tartrate, citrate, arsenate or more than100mg of phosphate, colour development is, however, liable to be slower. Details of certain interferences and means by which
27、they can be overcome are given in the Annex. 3 Principle Reduction of all the iron(III) present in the test solution to iron(II) with ascorbic acid. Formation ofthe orange-red complex between iron(II) and1,10-phenanthroline at a pH between2 and9, and spectrophotometric measurement of the absorbance
28、of the complex at the wavelength of maximum absorption(510nm). Under the specified conditions, the complex is measured at a pH between4 and6. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Hydrochloric acid
29、, 180g/l solution. Dilute, taking all necessary precautions,409ml of38% (m/m) hydrochloric acid solution, =1,19g/ml, to1000ml with water and mix well. 4.2 Ammonia, 85g/l solution. Dilute374ml of25% (m/m) ammonia solution, =0,910g/ml, to1000ml with water and mix well. 4.3 Sodium acetate/acetic acid b
30、uffer solution, pH4,5 at20 C. Dissolve164g of anhydrous sodium acetate in about500ml of water, add240ml of glacial acetic acid, and dilute to1000ml with water. 4.4 Ascorbic acid, 100g/l solution. Discard this solution after1 week. 4.5 1,10-Phenanthroline hydrochloride monohydrate (C 12 H 8 N 2 .HCl.
31、H 2 O), or1,10-phenanthroline monohydrate (C 12 H 8 N 2 .H 2 O),1g/l solution. Dissolve1g of either1,10-phenanthroline hydrochloride monohydrate or1,10-phenanthroline monohydrate in water and dilute to1000ml. Store the solution away from light. Use only colourless solutions. 4.6 Iron, standard solut
32、ion corresponding to0,200g of Fe per litre. Prepare by one of the following methods. 4.6.1 Weigh, to the nearest0,001g,1,727g of ammonium iron(III) sulphate dodecahydrate NH 4 Fe(SO 4 ) 2 .12H 2 O and dissolve it in about200ml of water. Transfer quantitatively to a1000ml one-mark volumetric flask, a
33、dd20ml of a(1+1) solution of concentrated sulphuric acid, dilute to the mark and mix. 1ml of this standard solution contains0,200mg ofFe. 4.6.2 Weigh, to the nearest0,001g,0,200g of pure(99,9%) iron wire, place in a100ml beaker and add10ml of concentrated hydrochloric acid, =1,19g/ml. Warm gently un
34、til completely dissolved, cool, transfer quantitatively to a1000ml one-mark volumetric flask, dilute to the mark and mix. 1ml of this standard solution contains0,200mg ofFe. 4.7 Iron, standard solution corresponding to0,020g of Fe per litre. Transfer50,0ml of the standard iron solution(4.6) to a500m
35、l one-mark volumetric flask, dilute to the mark and mix. 1ml of this standard solution contains204g of Fe. Prepare this solution at the time of use.BS6337-3:1983 2 BSI 12-1999 5 Apparatus Ordinary laboratory apparatus and 5.1 Spectrophotometer, fitted with cells of optical path length1,2 and4 or5cm.
36、 6 Procedure 6.1 Test portion and preparation of the test solution The mass of the test portion and details for preparation of the test solution will be given in the International Standard relating to the product concerned. 6.2 Blank test Prepare a blank test solution simultaneously with the test so
37、lution using exactly the same quantity of all the reagents used for the determination, diluting to the same volume and taking an aliquot portion having the same volume as that used in the determination. 6.3 Preparation of the calibration graphs 6.3.1 Preparation of standard colorimetric solutions fo
38、r spectrophotometric measurements with cells of optical path length1,2 and4 or5cm According to the expected iron content of the test solution, place the volumes of the standard iron solution(4.7), shown in Table 1, in a series of100ml one-mark volumetric flasks. 6.3.2 Colour development Treat the co
39、ntents of each flask as follows. Dilute, if necessary, to approximately60ml with water and, if necessary, adjust the pH to approximately2 with the hydrochloric acid solution(4.1), using narrow-range indicator paper to check the pH. Add1ml of the ascorbic acid solution(4.4), followed by20ml of the bu
40、ffer solution(4.3), and10ml of the1,10-phenanthroline solution(4.5), dilute to the mark with water and mix. Allow to stand for not less than15min. 6.3.3 Spectrophotometric measurements Carry out the spectrophotometric measurements using the spectrophotometer(5.1) at the wavelength of maximum absorpt
41、ion (about510nm) and in cells of appropriate optical path length (seeTable 1) after having adjusted the instrument to zero absorbance against water. 6.3.4 Plotting the graphs Deduct the absorbance of the blank test on the reagents for calibration from that of each standard colorimetric solution and
42、plot a graph having, for example, the mass, in micrograms, of iron (Fe) contained in100ml of standard colorimetric solution as abscissae and the corresponding values of absorbance as ordinates. 6.4 Determination 6.4.1 Colour development Take an aliquot portion of the test solution(6.1) containing no
43、t more than5004g of iron (Fe) in a volume of60ml and a similar aliquot portion of the blank test solution. Dilute, if necessary, to about60ml and adjust the pH, if necessary, to approximately2 with either the ammonia solution(4.2) or the hydrochloric acid solution(4.1), using a narrow-range indicato
44、r paper to check the pH. Transfer quantitatively the solutions to100ml one-mark volumetric flasks and develop the colour as specified in6.3.2, starting from “Add1ml of the ascorbic acid solution(4.4).”. 6.4.2 Spectrophotometric measurements Carry out the spectrophotometric measurements on the two so
45、lutions(6.4.1), after colour development, by the procedure specified in6.3.3. 7 Expression of results 7.1 Calculation By means of the calibration graphs(6.3.4), determine the masses of Fe corresponding to the absorbances of the aliquot portions of the test and blank test solutions taken for colour d
46、evelopment. The International Standards relating to the product in question will give the formulae to be applied for the final calculation. 7.2 Repeatability and reproducibility Experimental trials carried out in seven laboratories on aluminium sulphate, ammonium sulphate and disodium tetraborate, e
47、ach containing three levels of iron, gave the statistical results given in Table 2.BS6337-3:1983 BSI 12-1999 3 Table 1 Table 2 8 Test-report The test report shall include the following particulars: a) an identification of the sample; b) the reference of the general method used and of the Internation
48、al Standard relating to the product being analysed; c) the results and the method of expression used; d) any unusual features noted during the determination; e) any operation not included in this International Standard or in the International Standard relating to the product being analysed, or regar
49、ded as optional. Expected iron content of the aliquot portion of the test solution taken for the determination, 4g 50 to500 25 to250 10 to100 Standard iron solution (4.7) Corresponding mass of Fe Standard iron solution (4.7) Corresponding mass of Fe Standard iron solution (4.7) Corresponding mass of Fe ml 4g ml 4g ml 4g 0 a 2,50 5,00 10,00 15,00 20,00 25,00 0 50 100 200 300 400 500 0 a 3,00 5,00 7,00 9,00 11,00 13,00 0 60 100 140 180 220 260 0 a 0,50 1,00 2,00 3,00 4,00 5,00 0 10 20 40 60 80 100 Optical path length of spectrophotometer cell, cm 1 2 4 or5 a
