1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 6101-6:2011Rubber Determinationof metal content by atomicabsorption spectrometryPart 6: Determination of magnesiumcontentBS ISO 6101-6:2011 BRITISH STANDARDNational forewo
2、rdThis British Standard is the UK implementation of ISO 6101-6:2011.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/23, Test methods for rubber and non-blackcompounding ingredients.A list of organizations represented on this committee can beobtained on request to its
3、secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 74927 8ICS 83.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was publis
4、hed under the authority of theStandards Policy and Strategy Committee on 31 December 2011.Amendments issued since publicationDate Text affectedBS ISO 6101-6:2011Reference numberISO 6101-6:2011(E)ISO 2011INTERNATIONAL STANDARD ISO6101-6First edition2011-11-15Rubber Determination of metal content by a
5、tomic absorption spectrometry Part 6: Determination of magnesium content Caoutchouc Dosage du mtal par spectromtrie dabsorption atomique Partie 6: Dosage du magnsium BS ISO 6101-6:2011ISO 6101-6:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO 2011 All rights reserved. Unless otherwise specified, no part of
6、 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 copyright office Case postale 56 CH
7、-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 6101-6:2011ISO 6101-6:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword iv 1 Scope 1 2 Normative references 1 3 Terms and d
8、efinitions . 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 A (informative) Method of standar
9、d additions . 7 Annex B (informative) Precision 8 BS ISO 6101-6:2011ISO 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 work of preparing International Stan
10、dards 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-governmental, in liaison with ISO, also t
11、ake 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 main task of technical committees
12、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. Attention is drawn to the possibil
13、ity 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 SC 2, Testing and analysis. ISO 6101
14、 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: Determination of manganese content Part 5: De
15、termination of iron content Part 6: Determination of magnesium content BS ISO 6101-6:2011INTERNATIONAL STANDARD ISO 6101-6:2011(E) ISO 2011 All rights reserved 1Rubber Determination of metal content by atomic absorption spectrometry Part 6: Determination of magnesium content WARNING Persons using th
16、is 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 practices and to ensure compliance wi
17、th 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 appropriate documentation on safe hand
18、ling 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 references The following referenced
19、 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 124, Latex, rubber Determination of to
20、tal 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 porcelain and silica ISO 1795, Rubb
21、er, raw natural and raw synthetic Sampling and further preparative procedures BS ISO 6101-6:2011ISO 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 rubber latex concentrate natural rubber l
22、atex 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 rubber articles 4 Principle A test port
23、ion 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 285,2 nm, using a magnesium hollow-catho
24、de 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/cm3. 5.2 Dilute nitric acid, 1,6 % (by mass), prepa
25、red by carefully pipetting 11,5 cm3of concentrated nitric acid (5.1) into a 1 000 cm3one-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 commercially available standard magnesium s
26、olution. 5.4 Standard magnesium solution, containing 10 g of Mg per cubic centimetre, prepared by carefully pipetting 10 cm3of standard magnesium stock solution (5.3) into a 1 000 cm3one-mark volumetric flask, making up to the mark with dilute nitric acid (5.2) and mixing thoroughly. Prepare this so
27、lution 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 magnesium emission source. The instrument shall be
28、 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-stoppered, of capacities 50 cm3, 100 cm3and 1 000
29、cm3, complying with the requirements of ISO 1042:1998, class A. 6.5 Volumetric pipettes, of capacities 5 cm3, 10 cm3, 20 cm3and 50 cm3, complying with the requirements of ISO 648:2008, class A. BS ISO 6101-6:2011ISO 6101-6:2011(E) ISO 2011 All rights reserved 36.6 Graduated pipette, of capacity 1 cm
30、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 50cm3, complying with the requirements of ISO 1772. 6.10 Ashless filter paper. 7 Sampling Carry
31、 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 products made from natural rubber. 8 Procedure 8.1 Test portion 8.1.
32、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 into small pieces. 8.1.2 For raw, natural rubber, take the tes
33、t 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 (destruction of organic matter) Weigh out, to the nearest 0,1 m
34、g, 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 cm3. Heat the crucible containing the test portion over a bunsen burner or electric heater until all volatile material has evolved. Take care that the rubber does n
35、ot 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) and leave overnight or until all carbonaceous material is burn
36、ed off. 8.2.2 Dissolution of inorganic residue Add 10 cm3of 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 of the crucible into a 50 cm3one-mark volumetric flask, rinsing
37、 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 cm3one-mark volumetric flasks, introduce, using pipettes, the volumes of standard magnesium solution (5.4) indicated in Table
38、1. Make up to the mark with dilute nitric acid (5.2) and mix thoroughly. BS ISO 6101-6:2011ISO 6101-6:2011(E) 4 ISO 2011 All rights reservedPrepare the set of calibration solutions on the same day as the determination. Table 1 Standard calibration solutions Volume of standard magnesium solution cm3M
39、ass of magnesium contained in 1 cm3g 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, adjust the wavelength to 285,2 nm and the sensitivity and slit apertu
40、re 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 flame, suited to the characteristics of the particular spectrometer being
41、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. Aspirate water through the burner after each measurement. 8.3.3 Plotting the
42、 calibration graph Plot a graph having, for example, the masses, in micrograms, of magnesium contained in 1 cm3of the calibration solutions as abscissae and the corresponding values of absorbance, corrected for the absorbance of the calibration blank, as ordinates. Represent the points on the graph
43、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 the test solution prepared in 8.2.2, following the procedure specified in
44、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 procedure. Pipette carefully a suitable volume (V cm3) of the test solution int
45、o a 100 cm3one-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 thoroughly. Repeat the spectrometric measurements. Under certain circumstan
46、ces, the method of standard additions may be used (see Annex A). BS ISO 6101-6:2011ISO 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 dilute nitric acid (5.2), but omitting the test portion. 8.4.4 Number of dete
47、rminations 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 calibration graph plotted in 8.3.3. The magnesium content of the test portion, expres
48、sed as a percentage by mass, is given by the formula: tb(Mg) (Mg)200fm where (Mg)tis the magnesium content, in micrograms per cubic centimetre, of the test solution, read from the calibration graph; (Mg)bis the magnesium content, in micrograms per cubic centimetre, of the blank test solution, read f
49、rom 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: 100fV 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: tb(Mg) (Mg)200fm where (Mg)tis the magnesium content, in micrograms per cubic centim
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