1、BRITISH STANDARD BS7164-30.1: 1997 ISO6101-2: 1997 Chemical tests for raw and vulcanized rubber Part 30: Methods for determination of lead content Section 30.1 Atomic absorption spectrometry ICS 83.040.10; 83.060BS7164-30.1:1997 This British Standard, having been prepared under the directionof the S
2、ector Board for Materials and Chemicals, was published under the authority ofthe Standards Board and comesinto effect on 15 August1997 BSI09-1999 ISBN 0 580 28066 7 National foreword This British Standard reproduces ISO6101-2:1997 “Rubber Determination of metal content by atomic absorption spectrome
3、try Part2: Determination of lead content” and implements it as the UK national standard. It supersedes BS7164-30.1:1990 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PRI/23, Chemical testing of rubber, which has the responsibility to: aid enquirers
4、to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represe
5、nted on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondenc
6、e Index”, or using the “Find” facility of the BSI Standards Electronic Catalogue. 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
7、 confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theISO title page, pagesii to iv, pages1 to5 and a backcover. This standard has been updated (see copyright date) and may have had amendments incorporated. This wil
8、l be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBS7164-30.1:1997 BSI 09-1999 i Contents Page National foreword Inside front cover Foreword iii Text of ISO 6101-2 1ii blankBS7164-30.1:1997 ii BSI 09-1999 Contents Page Foreword
9、 iii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents 1 5 Apparatus 2 6 Sampling 2 7 Procedure 2 8 Expression of results 4 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 cali
10、bration solutions 3 Descriptors: Rubber, chemical analysis, determination of content, lead, atomic absorption spectrometric method.BS7164-30.1:1997 BSI 09-1999 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bod
11、ies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and
12、 non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bod
13、ies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO6101-2 was prepared by Technical Committee ISO/TC45, Rubber and rubber products. This second edition cancels and replaces the first edition (ISO610
14、1-2:1986), which has been technically revised. ISO6101 consists of the following parts, under the general title Rubber Determination of metal content by atomic absorption spectrometry: Part1: Determination of zinc content; Part2: Determination of lead content; Part3: Determination of copper content;
15、 Part4: Determination of manganese content; Part5: Determination of iron content. Annex A forms an integral part of this part of ISO6101.iv blankBS7164-30.1:1997 BSI 09-1999 1 WARNING Persons using this part of ISO6101 should be familiar with normal laboratory practice. This part of ISO6101 does not
16、 purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope This part of ISO6101 specifies an atomic absorption spe
17、ctrometric method for the determination of the lead content of rubbers. The method is applicable to raw rubber and rubber products. There is no limit to the concentration of lead that can be determined. High or low concentrations may be determined, provided that suitable adjustments are made to the
18、mass of the test portion and/or the concentration of the solutions used. The use of the standard-additions method may lower the bottom limit of detection. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of IS
19、O6101. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based 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
20、 ISO maintain registers of currently valid International Standards. ISO123:1985, Rubber latex Sampling. ISO247:1990, Rubber Determination of ash. ISO648:1977, Laboratory glassware One-mark pipettes. ISO1042:1983, Laboratory glassware One-mark volumetric flasks. ISO1772:1975, Laboratory crucibles in
21、porcelain and silica. ISO1795:1992, Rubber, raw, natural and synthetic Sampling and further preparative procedures. 3 Principle If the rubber does not contain halogenated compounds, a test portion is directly ashed at550 C 25 C as specified in ISO247:1990, method A. If the rubber contains halogenate
22、d compounds, a test portion is first mineralized with sulfuric and nitric acids, the acids are removed by evaporation, and the portion is ashed at550 C 25 C. NOTEThe presence of even small amounts of halogens may lead to the loss of volatile lead salts during dry ashing. The ash obtained is boiled w
23、ith ammonium acetate solution to dissolve the lead. Insoluble lead silicates, if present, are converted to chloride by boiling with a mixture of hydrochloric acid, nitric acid and hydrogen peroxide. The solution is aspirated into an atomic absorption spectrometer and the absorbance is measured at a
24、wavelength of283,3nm, using a lead hollow-cathode lamp as the lead emission source. NOTEISO6955:1982, Analytical spectroscopic methods Flame emission, atomic absorption, and atomic fluorescence Vocabulary, defines the spectrometric terms used in this part of ISO6101. 4 Reagents During the analysis,
25、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 Nitric acid, 20 =1,40Mg/m 3 . 4.3 Hydrochloric acid, 20 =1,18Mg/m 3 . 4.4 Hydrochloric acid, diluted1+2. Dilute1 volume of concen
26、trated hydrochloric acid(4.3) with2 volumes of water. 4.5 Hydrogen peroxide, 30% (m/m) solution. 4.6 Ammonium acetate, 180g/dm 3solution. 4.7 Standard lead stock solution, containing1g of Pb per cubic decimetre. Either use a commercially available standard lead solution, or prepare as follows: Weigh
27、, to the nearest0,1mg,1g of metallic lead (purity U 99,95%) and transfer to a100cm 3beaker(5.12). Add30cm 3of water and20cm 3of nitric acid(4.2) and boil on a sand-bath(5.10). If the lead is dissolved, continue boiling until the solution is reduced to about20cm 3or less. No nitrogen oxides should be
28、 observed. Otherwise, add water and continue boiling. Transfer to a1000cm 3 one-mark volumetric flask (see5.7) with1+2 hydrochloric acid(4.4) and fill to the mark with1+2 hydrochloric acid(4.4). 1cm 3of this standard stock solution contains1mg of Pb.BS7164-30.1:1997 2 BSI 09-1999 4.8 Standard lead s
29、olution, containing10mg of Pb per cubic decimetre. Carefully pipette10cm 3of the standard lead stock solution(4.7) into a1000cm 3one-mark volumetric flask (see5.7) dilute to the mark with1+2 hydrochloric acid(4.4), and mix thoroughly. Prepare this solution on the day of use. 1cm 3of this standard st
30、ock solution contains104g of Pb. 5 Apparatus Ordinary laboratory apparatus, plus the following: 5.1 Atomic absorption spectrometer, fitted with a burner fed with acetylene and air, compressed to at least60kPa and300kPa, respectively, and also fitted with a lead hollow-cathode lamp as the lead emissi
31、on 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 manufacturers instructions for
32、optimum performance, during drying, ashing and volatilization of the test portion. 5.2 Balance, accurate to0,1 mg. 5.3 Muffle furnace, capable of being maintained at550 C 25 C. 5.4 Evaporating dish, of capacity about100cm 3 , made of quartz glass, with a clock-glass cover. 5.5 Conical flask, of capa
33、city250cm 3 , made of silica or borosilicate glass. 5.6 Measuring cylinder, of capacity25cm 3 , graduated in0,5cm 3divisions. 5.7 One-mark volumetric flasks, glass-stoppered, of capacities50cm 3 ,100cm 3 ,200cm 3 ,500cm 3and1000cm 3 , complying with the requirements of ISO1042, class A. 5.8 Filter f
34、unnel, 65mm diameter,60 angle. 5.9 Volumetric pipettes, of capacities5cm 3 ,10cm 3 ,20cm 3and50cm 3 , complying with the requirements of ISO648, classA. 5.10 Electric hotplate or heated sand bath. 5.11 Steam bath 5.12 Beaker, of capacity100cm 3 . 5.13 Crucible, of platinum, and of capacity50cm 3to15
35、0cm 3depending on the test portion size. 5.14 Crucible, of silica or borosilicate glass, of capacity50cm 3to150cm 3depending on the test portion size, complying with the requirements of ISO1772. 6 Sampling Carry out sampling as follows: raw rubber: in accordance with ISO1795; latex: in accordance wi
36、th ISO123; products: to be representative of the whole batch. 7 Procedure 7.1 Test portion 7.1.1 If the rubber does not contain halogenated compounds, weigh, to the nearest0,1mg,0,5g to2,0g (depending on the expected lead content) of milled or finely cut rubber into a crucible(5.13 or5.14). NOTEIt i
37、s advisable to run the Beilstein test on a preliminary test portion for halogen content, as volatile lead compounds are possibly formed in the presence of halogen-containing admixtures. 7.1.2 If the rubber contains halogenated compounds (for example, in the case of chloroprene rubber), weigh, to the
38、 nearest0,1mg,0,5g to2,0g (depending on the expected lead content) of milled or finely cut rubber into the conical flask(5.5). 7.2 Preparation of test solution 7.2.1 Destruction of organic matter 7.2.1.1 If the rubber does not contain halogenated compounds, ash the test portion in accordance with me
39、thod A of ISO247:1990. 7.2.1.2 If the rubber contains halogenated compounds(7.1.2), use the following alternative procedure: To the flask containing the test portion, add10cm 3to15cm 3of sulfuric acid(4.1) and heat moderately on the electric hotplate or on the sand bath over a gas burner(5.10) until
40、 the rubber has disintegrated. Carefully add5cm 3of nitric acid(4.2). Continue heating until the rubber has completely decomposed and white fumes are evolved. Some rubber formulations cause considerable splashing; in this case, use a larger conical flask. Transfer the reaction mixture quantitatively
41、 into the evaporating dish(5.4), evaporate to dryness and ash in the muffle furnace(5.3), maintained at550 C 25 C, until all the carbon has burnedoff. 7.2.2 Dissolution of inorganic residue After cooling, boil the residue obtained in7.2.1.1 or7.2.1.2 with15cm 3of ammonium acetate solution(4.6) and f
42、ilter through a paper filter. Retain this filtrate (A) and ash the filter with the residue in the muffle furnace(5.3), maintained at550 C 25 C, until all the carbon has burnedoff.BS7164-30.1:1997 BSI 09-1999 3 Cool to room temperature, add a mixture of10cm 3of hydrochloric acid(4.3),5cm 3of nitric a
43、cid(4.2) and10 drops of hydrogen peroxide(4.5), then boil for about10min. Cool and filter the reaction mixture. Evaporate the filtrate on the steam bath(5.11) to dryness and take up the residue with water. Add this to filtrate A. Transfer the combined solutions, quantitatively, to a50cm 3one-mark vo
44、lumetric flask (see5.7) with hydrochloric acid(4.4). Dilute to the mark with hydrochloric acid(4.4) and proceed in accordance with7.4. Test solutions in hydrochloric acid shall be of the same concentration as in4.4. If evaporation, etc., has reduced or increased this concentration, adjust it accordi
45、ngly with concentrated hydrochloric acid(4.3) or with water. 7.3 Preparation of the calibration graph 7.3.1 Preparation of calibration solutions 7.3.1.1 Into a series of five100cm 3one-mark volumetric flasks (see5.7) introduce, using pipettes (see5.9), the volumes of standard lead solution(4.8) indi
46、cated in Table 1. Dilute to the mark with1+2 hydrochloric acid(4.4) and mix thoroughly. Table 1 Standard calibration solutions 7.3.1.2 Prepare the set of calibration solutions immediately prior to the determination. 7.3.1.3 If the test portion was prepared with sulfuric acid and ammonium acetate, us
47、e the same quantities in the calibration solutions and for the corresponding calibration blank. 7.3.2 Spectrometric measurements Switch on the spectrometer(5.1) sufficiently in advance to ensure stabilization. With the lead hollow-cathode lamp suitably positioned, adjust the wavelength to283,3nm and
48、 the sensitivity and slit aperture according 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 blue, non-luminous, oxidizing flame, suited to the characteristics of t
49、he particular spectrometer being used. Aspirate the set of calibration solutions in succession into the flame and measure the absorbance of each solution twice, averaging the readings. Take care that the aspiration rate is constant throughout this process. Ensure also that at least one calibration solution is at or below the analyte level found in the rubber being tested. Aspirate water through the burner after each measurement. If sulfuric acid has been used in the preparation of the test portion, it is
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