1、BRITISH STANDARD BS7164-27.2: 1990 ISO1657:1986 Chemical tests for raw and vulcanized rubber Part27: Methods for determination of iron content Section27.2 Photometric methodBS7164-27.2:1990 This British Standard, having been prepared under the directionof the Rubber StandardsPolicy Committee,waspubl
2、ished undertheauthorityof the BoardofBSIand comes intoeffecton 31July1990 BSI11-1999 The following BSI references relate to the work on this standard: Committee reference RUM/37 Draft for comment82/55911 DC ISBN 0 580 18771 3 Committees responsible for this British Standard The preparation of this B
3、ritish Standard was entrusted by the Rubber Standards Policy Committee (RUM/-) to Technical Committee RUM/37, upon which the following bodies were represented: Institute of Water and Environmental Management Laboratory of the Government Chemist Ministry of Defence Royal Society of Chemistry Rubber a
4、nd Plastics Research Association Amendments issued since publication Amd. No. Date CommentsBS7164-27.2:1990 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 References 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling
5、 2 7 Procedure 2 8 Expression of results 3 9 Test report 3 Publications referred to Inside back coverBS7164-27.2:1990 ii BSI 11-1999 National foreword This Section of BS7164 has been prepared under the direction of the Rubber Standards Policy Committee and is identical with ISO1657:1986 “Rubber, raw
6、 and rubber latexDetermination of iron content1,10-Phenanthroline photometric method”, published by the International Organization for Standardization (ISO). BS7164 rationalizes all the methods that deal with chemical analysis of raw, compounded and vulcanized rubber some of which have previously be
7、en published in BS903, BS1673 and BS5923. Relevant Parts of those standards will be withdrawn or deleted by amendment, as appropriate, when superseded by Parts and Sections of BS7164. This Section of BS7164 supersedes method2.8 of BS1673-2:1967, which will be deleted by amendment. A British Standard
8、 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. Cross-references International Standard Corresponding Briti
9、sh Standard ISO123:1985 BS6057 Rubber latices Part2:1987 Sampling (Identical) ISO124:1985 Section3.2:1987 Determination of total solids content (Identical) ISO247:1978 a BS5923 Methods for chemical analysis of rubber Part1:1980 Determination of ash (Identical) ISO1795:1974 ISO1796:1982 BS6315:1982 M
10、ethods for sampling and sample preparation of raw rubber (Technically equivalent) ISO4793:1980 BS1752:1983 Specification for laboratory sintered or fritted filters including porosity grading (Identical) a This will be superseded by the revised edition of ISO247 which is in preparation. It is envisag
11、ed that BS7164-5, which will supersede BS5923-1, will be identical to the revised edition of ISO247. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) and
12、 may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS7164-27.2:1990 BSI 11-1999 1 1 Scope and field of application This International Standard specifies a1,10-phenanthroline photometric method for the determination of5 to1000mg/kg of iron i
13、n uncompounded natural rubber, uncompounded synthetic rubbers which do not contain chlorine, and in the corresponding uncompounded latices. 2 References ISO123, Rubber latexSampling. ISO124, Rubber laticesDetermination of total solids content. ISO247, RubberAsh contentDetermination. ISO1795, Raw rub
14、ber in balesSampling. ISO1796, Raw rubberSample preparation. ISO4793, Laboratory sintered (fritted) filters Porosity grading, classification and designation. 3 Principle Ashing of the raw rubber or the dried latex solids in a crucible. Extraction of the ash with hydrochloric acid and making up of th
15、e solution to standard volume. After adjustment of the pH by the addition of buffer solution, treatment of an aliquot part of the solution with hydroxylammonium chloride to reduce any iron(III) present to iron(II) and1,10-phenanthroline with which the iron(II) forms an orange-red complex. Photometri
16、c measurement of the absorbance of this solution, which is proportional to the concentration of iron. NOTEThe method used is closely similar to that given in ISO6685, Chemical products for industrial useGeneral method for determination of iron content1,10-Phenanthroline spectrophotometric method. 4
17、Reagents All reagents shall be of recognized high purity analytical quality suitable for use in trace metal analysis. Distilled water or water of equivalent purity shall be used whenever water is specified. 4.1 Hydrochloric acid,A 1,19g/cm 31) . 4.2 1,10-Phenanthroline, solution. Dissolve0,5g of1,10
18、-phenanthroline monohydrate in hot water and, after cooling, provided that this does not cause precipitation, dilute the solution to500cm 3 . Store the solution away from the light and use only colourless solutions. 4.3 Hydroxylammonium chloride, solution. Dissolve10g of hydroxylammonium chloride in
19、100cm 3of water. 4.4 Buffer solution Dissolve164g of anhydrous sodium acetate in approximately250cm 3of water and to the solution add28,5cm 3of glacial acetic acid,A 1,05g/cm 3 . Dilute this mixture to500cm 3and filter immediately before use if it is cloudy. If this buffer solution gives highly colo
20、ured reference solutions in the preparation of the calibration curve, an alternative buffer solution may be prepared by dissolving80g of sodium hydroxide or106g of anhydrous sodium carbonate in200cm 3of water, adding142,5cm 3of glacial acetic acid,A 1,05g/cm 3 , and diluting the solution to500cm 3 .
21、 4.5 Iron, standard solution corresponding to0,1g of Fe per cubic decimetre. Dissolve0,702g, weighed to the nearest0,0005g, of ammonium iron(II) sulfate hexahydrate (NH 4 ) 2 Fe(SO 4 ) 2 .6H 2 O in water in a1000cm 3 one-mark volumetric flask. Add3cm 3of concentrated hydrochloric acid,A 1,19g/cm 3 ,
22、 and dilute to the mark with water. This solution will generally remain stable for at least1month. 1cm 3of this standard solution contains0,1mg of Fe. 4.6 Iron, standard solution for calibration corresponding to0,01g of Fe per cubic decimetre. Pipette10cm 3of the standard iron solution(4.5) into a10
23、0cm 3one-mark volumetric flask and dilute to the mark with water. 1cm 3of this standard solution contains0,01mg of Fe. This solution shall be freshly prepared from the stock solution(4.5) at the time of use. 5 Apparatus Ordinary laboratory apparatus and 5.1 Colorimeter or spectrophotometer, capable
24、of measuring absorbance at approximately510nm, with matched5cm cells. 5.2 Silica or porcelain crucible, nominal capacity50 to80cm 3 . 5.3 Muffle furnace, capable of maintaining a temperature of525 25 C. 1) The term millilitre (ml) is commonly used as a special name for the cubic centimetre (cm 3 ),
25、in accordance with a decision of the Twelfth Confrence Gnrale des Poids et Mesures. The term millilitre is acceptable, in general, for references in International Standards to capacities of volumetric glassware and to liquid volumes.BS7164-27.2:1990 2 BSI 11-1999 5.4 Heat-resistant board, iron-free,
26、 approximately100mm square and6mm thick, with a hole in the centre, or silica triangle. The hole in the heat-resistant board or the size of the silica triangle shall be such that approximately two-thirds of the crucible projects below the board. 5.5 One-mark volumetric flasks, of capacity50cm 3 . 5.
27、6 Graduated precision pipettes or burettes 5.7 Sintered glass crucible, of porosity P40 or P100 (seeISO4793). 6 Sampling For raw rubber, carry out the sampling in accordance with ISO1795. For latex, carry out the sampling in accordance with one of the methods specified in ISO123. 7 Procedure 7.1 Pre
28、paration of homogenized test piece For the determination of iron in raw rubber, prepare a homogenized sheet in accordance with ISO1796. For the determination of iron in latex, prepare a homogeneous sheet dried to constant mass, as specified in ISO124, using a portion of thoroughly mixed latex contai
29、ning at least10g of total solids. At all stages of sample preparation, take care to avoid contamination with iron, particularly from rusty knives, scissors, mills and other equipment unless chromed. 7.2 Preparation of calibration curve 7.2.1 Preparation of standard colorimetric solutions To a series
30、 of50cm 3one-mark volumetric flasks(5.5), add portions of the standard iron solution(4.6) ranging from0 to20cm 3(for example0;0,5;5;10;15;20cm 3 ). These portions contain0 to2004g of iron. 7.2.2 Colour development Add to each of the flasks in7.2.1,1cm 3of the concentrated hydrochloric acid(4.1),10cm
31、 3of the buffer solution(4.4),1cm 3of the hydroxylammonium chloride solution(4.3) and10cm 3of the1,10-phenanthroline solution(4.2). Dilute the solutions with water to the mark and mix thoroughly. Allow to stand at room temperature for15min. 7.2.3 Photometric measurements Measure the absorbance of th
32、e solutions using the colorimeter or spectrophotometer(5.1) at the absorption maximum (about510nm) using the matched5cm cells. Correct the reading by subtracting the absorbance of the solution containing no added iron. If the absorbance is measured on a double-beam instrument, place the cell contain
33、ing the blank solution in the reference beam and measure the absorbance of each standard matching solution against that of the solution containing no added iron. 7.2.4 Plotting the graph Plot the reading thus obtained for each solution of7.2.1 against the appropriate concentration of iron to give th
34、e calibration curve, which shall be checked periodically according to local conditions and the type of instrument used. 7.3 Determination WARNINGAll precautions and safeguards required for the carrying out of trace metals analysis must be observed. 7.3.1 Preparation of test solution Cut into small p
35、ieces, each weighing approximately0,1g, a10g test portion of the homogenized test piece(7.1), prepared from the raw rubber or the dried latex. Transfer to the unetched crucible(5.2) and weigh to the nearest0,01g. Support the crucible in the hole cut in the heat-resistant board(5.4). Heat gently with
36、 a small 2)gas flame until a dry carbonaceous residue remains and then transfer the crucible to the muffle furnace(5.3), maintained at a temperature of550 25 C. Alternatively, wrap the weighed sample in a piece of ashless filter paper about150mm in diameter and transfer to the crucible. Place the cr
37、ucible and its contents in the furnace at550 25 C and close the furnace door. WARNINGThe furnace door must not be opened during the first hour because of the risk of igniting flammable gases. When all the carbon has been oxidized, remove the crucible and allow to cool. 2) Overheating may cause loss
38、of iron when silica crucibles are used.BS7164-27.2:1990 BSI 11-1999 3 Add5cm 3of the hydrochloric acid(4.1) and5cm 3of water to the crucible and digest the mixture on a steam bath for30 to60min. If the solution has a deep yellow colour, indicating the presence of much iron, add a further5cm 3of the
39、hydrochloric acid and digest for a further30min. Filter the solution through a sintered glass crucible(5.7), transfer the filtrate to a50cm 3one-mark volumetric flask(5.5) and, after cooling, dilute to the mark. 7.3.2 Colour development Transfer an aliquot part of the test solution(7.3.1) containing
40、 not more than2cm 3of hydrochloric acid(4.1), or4004g of iron to a50cm 3one-mark volumetric flask. Add10cm 3of the buffer solution(4.4), then1cm 3of the hydroxylammonium chloride solution(4.3) and10cm 3of the1,10-phenanthroline solution(4.2). Dilute the solution with water to the mark and mix thorou
41、ghly. Allow to stand at room temperature for15min. 7.3.3 Blank test In parallel with the determination and following the same procedure, carry out a blank determination using a similar filter paper and crucible and using the same quantities of all the reagents as used for the determination. 7.3.4 Ph
42、otometric measurements Carry out the photometric measurements on the test solution(7.3.1), and on the blank test solution(7.3.3) after colour development, measuring the absorbance of the solution at the wavelength used for preparing the calibration curve. Correct the reading for the test solution by
43、 subtracting the value for the absorbance of the blank solutions. If the absorbance is measured on a double-beam instrument, place the cell containing the blank solution in the reference beam and measure the absorbance of the test solution against the blank solution. 8 Expression of results By means
44、 of the calibration curve, determine the concentration of iron corresponding to the corrected reading and from this calculate the iron content of the test portion. Express the result as parts per million (ppm) of iron(Fe) calculated by mass. 9 Test report The test report shall include the following
45、particulars: a) reference to this International Standard; b) identification of the test sample; 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 Standards to
46、which reference is made, or regarded as optional.4 blankBS7164-27.2:1990 BSI 11-1999 Publications referred to Seenational foreword.BS7164-27.2: 1990 ISO1657:1986 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing Bri
47、tishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions. It is th
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