1、raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication BS ISO 6101-6:2011 Rubber Determination of metal content by atomic absorption spectrometry Part 6: Determination of magnesium contentBS ISO 6101-6:2011 BRITISH STANDARD Nation
2、al foreword This British Standard is the UK implementation of ISO 6101-6:2011. The UK participation in its preparation was entrusted to Technical Committee PRI/23, Test methods for rubber and non-black compounding ingredients. A list of organizations represented on this committee can be obtained on
3、request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 74927 8 ICS 83.060 Compliance with a British Standard cannot confer immunity from legal obligations. This Brit
4、ish Standard was published under the authority of the Standards Policy and Strategy Committee on 31 December 2011. Amendments issued since publication Date Text affectedBS ISO 6101-6:2011Reference number ISO 6101-6:2011(E) ISO 2011INTERNATIONAL STANDARD ISO 6101-6 First edition 2011-11-15 Rubber Det
5、ermination of metal content by atomic absorption spectrometry Part 6: Determination of magnesium content Caoutchouc Dosage du mtal par spectromtrie dabsorption atomique Partie 6: Dosage du magnsium BS ISO 6101-6:2011 ISO 6101-6:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO 2011 All rights reserved. Unles
6、s otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO co
7、pyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedBS ISO 6101-6:2011 ISO 6101-6:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword iv 1 Scope 1 2 No
8、rmative references 1 3 Terms and definitions . 2 4 Principle . 2 5 Reagents 2 6 Apparatus . 2 7 Sampling 3 8 Procedure . 3 8.1 Test portion 3 8.2 Preparation of test solution 3 8.3 Preparation of calibration graph 3 8.4 Determination 4 8.5 Expression of results 5 9 Precision 6 10 Test report 6 Annex
9、 A (informative) Method of standard additions . 7 Annex B (informative) Precision 8 BS ISO 6101-6:2011 ISO 6101-6:2011(E) iv ISO 2011 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The w
10、ork 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 non-govern
11、mental, 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. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The
12、 main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
13、 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 6101-6 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee S
14、C 2, Testing and analysis. ISO 6101 consists of the following parts, under the general title Rubber Determination of metal content by atomic absorption spectrometry: Part 1: Determination of zinc content Part 2: Determination of lead content Part 3: Determination of copper content Part 4: Determinat
15、ion of manganese content Part 5: Determination of iron content Part 6: Determination of magnesium content BS ISO 6101-6:2011 INTERNATIONAL STANDARD ISO 6101-6:2011(E) ISO 2011 All rights reserved 1Rubber Determination of metal content by atomic absorption spectrometry Part 6: Determination of magnes
16、ium content WARNING Persons using this part of ISO 6101 should be familiar with normal laboratory practice. This part of ISO 6101 does not 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 p
17、ractices and to ensure compliance with any national regulatory conditions. IMPORTANT Certain procedures specified in this part of ISO 6101 might involve the use or generation of substances, or the generation of waste, that could constitute a local environmental hazard. Reference should be made to ap
18、propriate documentation on safe handling and disposal after use. 1 Scope This part of ISO 6101 specifies an atomic absorption spectrometric method for the determination of the magnesium content of natural rubber latex concentrate, raw natural rubber and products made from natural rubber. 2 Normative
19、 references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 123, Rubber latex Sampling ISO 12
20、4, Latex, rubber Determination of total solids content ISO 247, Rubber Determination of ash ISO 648:2008, Laboratory glassware Single-volume pipettes ISO 835:2007, Laboratory glassware Graduated pipettes ISO 1042:1998, Laboratory glassware One-mark volumetric flasks ISO 1772, Laboratory crucibles in
21、 porcelain and silica ISO 1795, Rubber, raw natural and raw synthetic Sampling and further preparative procedures BS ISO 6101-6:2011 ISO 6101-6:2011(E) 2 ISO 2011 All rights reserved3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 natural rubb
22、er latex concentrate natural rubber latex from Hevea brasiliensis, containing ammonia and/or other preservatives, and which has been subjected to some process of concentration 3.2 raw natural rubber natural rubber, usually in bales or packages, forming the starting material for the manufacture of ru
23、bber articles 4 Principle A test portion is ashed at 550 C 25 C, or at 950 C 25 C for rubber products having a high carbon black content. The ash is dissolved in dilute nitric acid. The solution is aspirated into an atomic absorption spectrometer and the absorption is measured at a wavelength of 285
24、,2 nm, using a magnesium hollow- cathode lamp as the magnesium emission source. 5 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 5.1 Concentrated nitric acid, density 1,41 g/cm 3 . 5.2 Di
25、lute nitric acid, 1,6 % (by mass), prepared by carefully pipetting 11,5 cm 3of concentrated nitric acid (5.1) into a 1 000 cm 3one-mark volumetric flask, making up to the mark with water and mixing thoroughly. 5.3 Standard magnesium stock solution, containing 1 mg of Mg per cubic centimetre. Use a c
26、ommercially available standard magnesium solution. 5.4 Standard magnesium solution, containing 10 g of Mg per cubic centimetre, prepared by carefully pipetting 10 cm 3of standard magnesium stock solution (5.3) into a 1 000 cm 3one-mark volumetric flask, making up to the mark with dilute nitric acid
27、(5.2) and mixing thoroughly. Prepare this solution preferably on the day of use. 6 Apparatus 6.1 Atomic absorption spectrometer, fitted with a burner fed with acetylene and air compressed to at least 60 kPa and 300 kPa, respectively, and also fitted with a magnesium hollow-cathode lamp as the magnes
28、ium emission source. The instrument shall be operated in accordance with the manufacturers instructions for optimum performance. 6.2 Balance, accurate to 0,1 mg. 6.3 Muffle furnace, capable of being maintained at a temperature of 550 C 25 C or 950 C 25 C. 6.4 One-mark volumetric flasks, glass-stoppe
29、red, of capacities 50 cm 3 , 100 cm 3and 1 000 cm 3 , complying with the requirements of ISO 1042:1998, class A. 6.5 Volumetric pipettes, of capacities 5 cm 3 , 10 cm 3 , 20 cm 3and 50 cm 3 , complying with the requirements of ISO 648:2008, class A. BS ISO 6101-6:2011 ISO 6101-6:2011(E) ISO 2011 All
30、 rights reserved 36.6 Graduated pipette, of capacity 1 cm 3 , complying with the requirements of ISO 835:2007, class A. 6.7 Steam bath. 6.8 Borosilicate-glass rod, for use as a stirrer. 6.9 Crucible, of silica, porcelain or borosilicate glass, of nominal capacity 50cm 3 , complying with the requirem
31、ents of ISO 1772. 6.10 Ashless filter paper. 7 Sampling Carry out sampling in accordance with one of the methods specified in ISO 123 for natural rubber latex, in accordance with ISO 1795 for raw, natural rubber and on a milled or finely cut test sample representative of the whole sample for product
32、s made from natural rubber. 8 Procedure 8.1 Test portion 8.1.1 For natural rubber latex concentrate, take a portion of thoroughly mixed latex containing about 10 g of total solids, make into a thin film by pouring the portion onto a glass plate, dry to constant mass as specified in ISO 124 and cut i
33、nto small pieces. 8.1.2 For raw, natural rubber, take the test portion from a test sample prepared in accordance with ISO 1795. 8.1.3 For products made from natural rubber, take the test portion from a milled or finely cut test sample. 8.2 Preparation of test solution 8.2.1 Ashing of test portion (d
34、estruction of organic matter) Weigh out, to the nearest 0,1 mg, a test portion of approximately 3 g. Wrap the test portion in an ashless filter paper and place in a crucible of nominal capacity 50 cm 3 . Heat the crucible containing the test portion over a bunsen burner or electric heater until all
35、volatile material has evolved. Take care that the rubber does not ignite. If any material is lost due to spurting or frothing, repeat the above procedure with a new test portion. Place in a muffle furnace set at a temperature of 550 C 25 C (or 950 C 25 C for rubbers with a high carbon black content)
36、 and leave overnight or until all carbonaceous material is burned off. 8.2.2 Dissolution of inorganic residue Add 10 cm 3of dilute nitric acid (5.2) to the cooled residue. Cover with a watch glass and heat on a steam bath for at least 30 min. Allow to cool to ambient temperature. Filter the contents
37、 of the crucible into a 50 cm 3one- mark volumetric flask, rinsing the crucible and making up to the mark with dilute nitric acid (5.2). 8.3 Preparation of calibration graph 8.3.1 Preparation of standard solutions Into a series of five 100 cm 3one-mark volumetric flasks, introduce, using pipettes, t
38、he volumes of standard magnesium solution (5.4) indicated in Table 1. Make up to the mark with dilute nitric acid (5.2) and mix thoroughly. BS ISO 6101-6:2011 ISO 6101-6:2011(E) 4 ISO 2011 All rights reservedPrepare the set of calibration solutions on the same day as the determination. Table 1 Stand
39、ard calibration solutions Volume of standard magnesium solution cm 3Mass of magnesium contained in 1 cm 3g 50 20 10 5 0 5 2 1 0,5 0 8.3.2 Spectrometric measurements Switch on the spectrometer sufficiently in advance to ensure stabilization. With the magnesium hollow- cathode lamp suitably positioned
40、, adjust the wavelength to 285,2 nm and the sensitivity and slit aperture according to the characteristics of the instrument. Adjust the pressure and flow rate of the air and of the acetylene in accordance with the manufacturers instructions so as to obtain a clear, blue, non-luminous, oxidizing fla
41、me, suited to the characteristics of the 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. Aspir
42、ate water through the burner after each measurement. 8.3.3 Plotting the calibration graph Plot a graph having, for example, the masses, in micrograms, of magnesium contained in 1 cm 3of the calibration solutions as abscissae and the corresponding values of absorbance, corrected for the absorbance of
43、 the calibration blank, as ordinates. Represent the points on the graph by the best straight line as judged visually or as calculated by a least-squares fitting method. 8.4 Determination 8.4.1 Spectrometric measurements Carry out duplicate spectrometric measurements at a wavelength of 285,2 nm on th
44、e test solution prepared in 8.2.2, following the procedure specified in 8.2. 8.4.2 Dilution If the instrument response for the test solution is greater than that found for the calibration solution having the highest magnesium content, dilute the test solution in accordance with the following procedu
45、re. Pipette carefully a suitable volume (V cm 3 ) of the test solution into a 100 cm 3one-mark volumetric flask so that, after making up to the mark, the magnesium concentration will lie within the range covered by the calibration solutions. Make up to the mark with dilute nitric acid (5.2) and mix
46、thoroughly. Repeat the spectrometric measurements. Under certain circumstances, the method of standard additions may be used (see Annex A). BS ISO 6101-6:2011 ISO 6101-6:2011(E) ISO 2011 All rights reserved 58.4.3 Blank determination Carry out a blank test in parallel with the determination, using d
47、ilute nitric acid (5.2), but omitting the test portion. 8.4.4 Number of determinations Carry out the procedure in duplicate, using separate test portions taken from the same homogenized test sample. 8.5 Expression of results Read the magnesium content of the test solution directly from the calibrati
48、on graph plotted in 8.3.3. The magnesium content of the test portion, expressed as a percentage by mass, is given by the formula: tb (Mg) (Mg) 200 f m where (Mg) tis the magnesium content, in micrograms per cubic centimetre, of the test solution, read from the calibration graph; (Mg) bis the magnesi
49、um content, in micrograms per cubic centimetre, of the blank test solution, read from the calibration graph; m is the mass, in grams, of the test portion; f is the test solution dilution factor, if required (see 8.4.2), given by: 100 f V where V is the volume, in cubic centimetres, of test solution taken in 8.4.2. The magnesium content of the test portion can also be calculated, in micrograms per cubic centimetre, of the test solution, by the following formula:
