1、BRITISH STANDARD BS7164-29.1: 1992 ISO6101-1: 1991 Chemical tests for raw and vulcanized rubber Part29: Methods for determination of zinc content Section29.1 Atomic absorption spectrometryBS7164-29.1:1992 This British Standard, having been prepared under the directionof the Plastics andRubber Standa
2、rds PolicyCommittee, was publishedunder the authorityofthe Standards Boardand comes into effect on 28 February1992 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference PRM/23 Draft for comment88/44573 DC ISBN 0 580 20648 3 Committees responsible for this
3、British Standard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/23, upon which the following bodies were represented: Institute of Water and Environmental Management Laboratory of the Government Chemist
4、Ministry of Defence Royal Society of Chemistry Rubber and Plastics Research Association Amendments issued since publication Amd. No. Date CommentsBS7164-29.1:1992 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle
5、 1 4 Reagents 1 5 Apparatus 2 6 Sampling 2 7 Procedure 2 8 Expression of results 3 9 Test report 4 Annex A (normative) Method of standard additions 5 Figure A.1 Example of graph obtained using the method of standard additions 5 Table 1 Standard calibration solutions 3 Publication(s) referred to Insi
6、de back coverBS7164-29.1:1992 ii BSI 10-1999 National foreword This Section of BS7164 has been prepared under the direction of the Plastics and Rubber Standards Policy Committee and is identical with ISO6101-1:1991 “Rubber Determination of metal content by atomic absorption spectrometry Part1: Deter
7、mination of zinc content” 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 been published in BS903, BS1673 and BS5923. Relevant Parts of
8、those standards will be withdrawn or deleted by amendment, as appropriate, when superseded by Parts and Sections of BS7164. The Technical Committee has reviewed the provisions of ISO648:1977, ISO1772:1975 and ISO1795:1974 1) , to which reference is made in the text, and has decided that they are acc
9、eptable for use in conjunction with this standard. A related British Standard to ISO648 is BS1583:1986 “Specification for one-mark pipettes.” A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct applic
10、ation. 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, pagesi andii, pages1 to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and
11、 may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Cross-references International Standard Corresponding British Standard ISO123:1985 BS6057 Rubber latices Part2:1987 Sampling (Identical) ISO247:1990 BS7164 Chemical tests for raw and vulca
12、nized rubber Part5:1991 Methods for determination of ash content (Identical) ISO1042:1983 BS1792:1982 Specification for one-mark volumetric flasks (Identical) ISO4793:1980 BS1752:1983 Specification for laboratory sintered or fritted filters including porosity grading (Identical) 1) When the new edit
13、ion of ISO1795 is published it is intended that it be dual-numbered as BS7164-2.1.BS7164-29.1:1992 BSI 10-1999 1 1 Scope This part of ISO6101 specifies an atomic absorption spectrometric method for the determination of the zinc content of rubbers. The method is applicable to raw rubber and rubber pr
14、oducts having zinc contents at a minimum of0,05% (m/m). Zinc contents below this limit may be determined, provided that suitable adjustments are made to the mass of the test portion and/or to the concentrations of the solutions used. The use of the standard additions method may lower the bottom limi
15、t of detection. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO6101. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements base
16、d on this part of ISO6101 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO123:1985, Rubber latex Sampling. ISO247:1990, Rubber Determination o
17、f ash. ISO648:1977, Laboratory glassware One-mark pipettes. ISO1042:1983, Laboratory glassware One-mark volumetric flasks. ISO1772:1975, Laboratory crucibles in porcelain and silica. ISO1795:, Rubber, raw, natural and synthetic Sampling and further preparative procedures (Combined revision of ISO179
18、5:1974 and ISO1796:1982, also incorporating ISO/TR2630:1978) 2) . ISO4793:1980, Laboratory sintered (fritted) filters Porosity grading, classification and designation. 3 Principle A test portion is ashed at550 C 25 C in accordance with ISO247, method A or B. The ash is dissolved in hydrochloric acid
19、. The solution is aspirated into an atomic absorption spectrometer and the absorption is measured at a wavelength of213,8nm, using a zinc hollow-cathode lamp as the zinc emission source. Any silicates are volatilized by sulfuric acid and hydrofluoric acid. NOTE 1ISO6955:1982, Analytical spectroscopi
20、c methods Flame emission, atomic absorption, and atomic fluorescence Vocabulary, defines the spectrometric terms used in this part of ISO6101. 4 Reagents WARNING All recognized health and safety precautions shall be observed when carrying out the procedures specified in this part of ISO6101. During
21、the analysis, unless otherwise stated, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 4.1 Sulfuric acid, 20=1,84Mg/m 3 . 4.2 Hydrochloric acid, 20=1,18Mg/m 3 . 4.3 Hydrochloric acid solutions 4.3.1 Hydrochloric acid, diluted1+2. Dilute1volum
22、e of the concentrated hydrochloric acid (4.2) with2volumes of water. 4.3.2 Hydrochloric acid, diluted1+100. Dilute1volume of the concentrated hydrochloric acid (4.2) with100volumes of water. 4.4 Hydrofluoric acid, 20=1,13Mg/m 3 ,38%(m/m) to40%(m/m). 4.5 Nitric acid, 20=1,42Mg/m 3 . 4.6 Zinc, standar
23、d stock solution containing1g of Zn per cubic decimetre. Either use a commercially available standard zinc solution, or prepare as follows. Weigh, to the nearest0,1mg,1g of pure zinc dust (minimum purity99,9%) and dissolve in a minimum amount of the1+2 hydrochloric acid solution (4.3.1). Allow to co
24、ol and transfer quantitatively to a1000cm 3one-mark volumetricflask (5.5). Make up to the mark with1+100hydrochloric acid solution (4.3.2) and mix thoroughly. 1cm 3of this standard stock solution contains10004g of Zn. 4.7 Zinc, standard solution corresponding to10mg of Zn per cubic decimetre. Using
25、a pipette (5.6), carefully introduce10cm 3of the standard stock zinc solution (4.6) into a1000cm 3one-mark volumetric flask (5.5). Dilute to the mark with1+2 hydrochloric acid solution(4.3.1) and mix thoroughly. Prepare this solution on the day of use. 1cm 3of this standard solution contains104g of
26、Zn. 2) To be published. (Revision of ISO1795:1974)BS7164-29.1:1992 2 BSI 10-1999 5 Apparatus Ordinary laboratory apparatus and 5.1 Atomic absorption spectrometer, fitted with a burner fed with acetylene and air compressed respectively to at least60kPa and300kPa, and also fitted with a zinc hollow-ca
27、thode lamp as the zinc emission source. The instrument shall be operated in accordance with the manufacturers instructions for optimum performance. Alternatively, an electrothermal atomization device (graphite furnace) may be used. It shall be operated by a competent person in accordance with the ma
28、nufacturers instructions for optimum performance, using the test solution as prepared in7.2. 5.2 Balance, accurate to0,1mg. 5.3 Muffle furnace, capable of being maintained at a temperature of550 C 25 C. 5.4 Beaker, of capacity250cm 3 . 5.5 One-mark volumetric flasks, glass-stoppered, of capacity50cm
29、 3 ,100cm 3 ,200cm 3 ,500cm 3and1000cm 3 , complying with the requirements of ISO1042, class A. 5.6 One-mark volumetric pipettes, of capacity5cm 3 ,10cm 3 ,20cm 3and50cm 3 , complying with the requirements of ISO648, classA. 5.7 Filter funnel, of diameter65mm and angle60 , fitted with a sintered-gla
30、ss disc of pore size164m to404m (porosity grade P40 see ISO4793). 5.8 Silica or porcelain crucible, of capacity50cm 3 , complying with the requirements of ISO1772. 5.9 Platinum crucible, of capacity50cm 3 . 5.10 Platinum rod, for use as stirrer. 5.11 Filter paper, ashless, acid-resistant or glass-fi
31、bre, of diameter110mm. 5.12 Electric heating plate or sand bath heated by a gas burner. 5.13 Conical flask, of capacity250cm 3 . 6 Sampling Carry out sampling as follows: raw rubber: in accordance with ISO1795; latex: in accordance with ISO123; products: to be representative of the whole batch. 7 Pr
32、ocedure 7.1 Test portion 7.1.1 If ashing is to be carried out by method A or method B of ISO247, weigh, to the nearest0,1mg,0,1g of milled or finely cut rubber into the appropriate crucible (5.8 or5.9). 7.1.2 If the rubber contains halogenated compounds (for example, in the case of chloroprene rubbe
33、r), weigh, to the nearest0,1mg,0,1g of milled or finely cut rubber into a250cm 3conical flask (5.13). 7.2 Preparation of test solution 7.2.1 Destruction of organic matter 7.2.1.1 Ash the test portion (7.1.1) in accordance with method A or method B of ISO247, using the muffle furnace (5.3) maintained
34、 at550 C 25 C. Weighing of the ash is unnecessary. 7.2.1.2 If the rubber contains halogenated compounds, carry out destruction of the organic matter in the test portion (7.1.2) in accordance with the following alternative procedure. Add to the test portion (7.1.2),10cm 3to15cm 3of sulfuric acid (4.1
35、) and heat moderately until the test portion has disintegrated. Carefully add5cm 3of nitric acid (4.5). Continue heating until the test portion has completely decomposed and white fumes are evolved. Some rubber formulations cause considerable splashing; in this case, use a larger conical flask. 7.2.
36、2 Dissolution of inorganic residue 7.2.2.1 Add carefully20cm 3of1+2 hydrochloric acid (4.3.1) to the residue. (Carbonates cause splashing and foaming.) Transfer the solution and the residue to a beaker(5.4) with50cm 3of1+2 hydrochloric acid solution (4.3.1) and heat for30min. If the residue dissolve
37、s completely, transfer to a100cm 3volumetric flask (5.5), dilute to the mark with1+2 hydrochloric acid solution (4.3.1), and proceed in accordance with7.4. 7.2.2.2 If the ash is not totally dissolved when following the procedure described in7.2.2.1, repeat the ashing in accordance with7.2.1.1 or7.2.
38、1.2 using a new test portion, and proceed as follows. Transfer the ash from the new test portion to a platinum crucible (5.9). Add a few drops of sulfuric acid (4.1) and heat to fuming. Cool and add a further3 drops of sulfuric acid (4.1) and5cm 3of hydrofluoric acid (4.4). Heat on the electric heat
39、ing plate or sand bath (5.12) in a fume cupboard and evaporate to dryness, while stirring with the platinum rod (5.10). Repeat this digestion with the same quantities of sulfuric and hydrofluoric acids two more times.BS7164-29.1:1992 BSI 10-1999 3 Cool, add50cm 3of1+2 hydrochloric acid solution(4.3.
40、1) and filter. Wash the filter with1+2 hydrochloric acid solution (4.3.1) and combine the filtrate and washings in a100cm 3volumetric flask (5.5). Dilute to the mark with1+2hydrochloric acid solution (4.3.1) and mixthoroughly. Proceed in accordance with7.4. 7.2.2.3 Test solutions should contain appr
41、oximately12% hydrochloric acid. If evaporation or reaction with carbonates, etc., has reduced or increased this concentration, adjust it accordingly with concentrated hydrochloric acid(4.2) or water. 7.3 Preparation of the calibration graph 7.3.1 Preparation of standard calibration solutions 7.3.1.1
42、 Into a series of five100cm 3one-mark volumetric flasks (5.5), introduce, using pipettes(5.6), the volumes of the standard zinc solution (4.7) indicated in Table 1. Dilute to the mark with1+2 hydrochloric acid solution (4.3.1) and mix thoroughly. Table 1 Standard calibration solutions 7.3.1.2 Prepar
43、e fresh standard calibration solutions daily. 7.3.2 Spectrometric measurements Switch on the spectrometer (5.1) sufficiently in advance to ensure stabilization. With the zinc hollow-cathode lamp suitably positioned, adjust the wavelength to213,8nm and the sensitivity and the slit aperture according
44、to the characteristics of the instrument. Adjust the pressures and flow rates of the air and of the acetylene in accordance with the manufacturers instructions so as to obtain a clear, non-luminous, oxidizing flame, suited to the characteristics of the particular spectrometer being used. Aspirate th
45、e series of standard calibration solutions(7.3.1.1) in succession into the flame, and measure the absorbance of each solution twice, averaging the readings. Take care to ensure that the rate of aspiration is constant throughout this process. Ensure also that at least one calibration solution is at o
46、r below the level of the zinc concentration in the test solution. Aspirate water through the burner after each measurement. 7.3.3 Plotting the calibration graph Plot a graph having, for example, the masses, in micrograms, of zinc contained in1cm 3of the standard calibration solutions as abscissae, a
47、nd the corresponding values of absorbance, corrected for the absorbance of the calibration blank solution (see7.3.1.1), as ordinates. Represent the points on the graph by the best straight line as judged visually, or calculated by the least-square fit method. 7.4 Determination 7.4.1 Spectrometric me
48、asurements Carry out duplicate spectrometric measurements at a wavelength of213,8nm on the test solution(7.2.2), following the procedure specified in7.3.2. 7.4.2 Dilution If the instrument response for the test solution is greater than that for the standard calibration solution having the highest zi
49、nc content (see7.3.1.1), dilute as appropriate with1+2hydrochloric acid solution (4.3.1) in accordance with the following procedure. Pipette carefully a suitable volume (V cm 3 ) of the test solution (7.2.2) into a100cm 3one-mark volumetric flask (5.5) so that the zinc concentration lies within the range covered by the standard calibration solutions. Dilute to the mark with the1+2 hydrochloric acid solution (4.3.1). Repeat the spectrometric measurements. NOTE 2To increase the reliability of the test method, the standard ad
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