ISO/DIS 11853

Rubber -- Determination of magnesium content of raw natural rubber and rubber products by atomic absorption spectrometry

Caoutchouc -- Détermination de la teneur en magnésium du caoutchouc naturel brut et des produits en caoutchouc par spectrométrie d'absorption atomique

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD ISO/DIS 11853
ISO/TC 45/SC 2 Secretariat: SIS
Voting begins on: Voting terminates on:
2009-08-21 2010-01-21

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION

Rubber — Determination of magnesium content of raw natural
rubber and rubber products by atomic absorption spectrometry

Caoutchouc — Détermination de la teneur en magnésium du caoutchouc naturel brut et des produits en

caoutchouc par spectrométrie d'absorption atomique
ICS 83.040.10; 83.140.01

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International Organization for Standardization, 2009
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ISO/DIS 11853
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ii ISO 2009 – All rights reserved
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ISO/DIS 11853
Contents Page

Foreword ............................................................................................................................................................iv

1 Scope......................................................................................................................................................1

2 Normative References...........................................................................................................................1

3 Terms and definitions ...........................................................................................................................1

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 Spectrometric measurements..............................................................................................................4

8.5 Plotting the calibration graph ..............................................................................................................4

8.6 Determination ........................................................................................................................................4

8.7 Dilution ...................................................................................................................................................4

8.8 Blank determination..............................................................................................................................5

8.9 Number of determinations....................................................................................................................5

8.10 Expression of results............................................................................................................................5

9 Precision ................................................................................................................................................6

10 Test report..............................................................................................................................................6

Annex A (Informative) Method of standard additions ....................................................................................7

Annex B (Informative) Precision.......................................................................................................................8

© ISO 2009 – All rights reserved iii
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ISO/DIS 11853
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). 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

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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The 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.

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 11853 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee

SC 2, Testing and analysis.
iv © ISO 2009 – All rights reserved
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DRAFT INTERNATIONAL STANDARD ISO/DIS 11853
Rubber — Determination of magnesium content of raw natural
rubber and rubber products by atomic absorption spectrometry

WARNING — Persons using this International Standard should be familiar with normal laboratory

practice. This standard 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 with any national regulatory conditions.

CAUTION — Certain procedures specified in this International Standard may 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 handling and disposal after

use.
1 Scope

This International Standard 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 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, Natural rubber latex concentrates – Determination of total solids content

ISO 247, Rubber -- Determination of ash
ISO 648:2008, Laboratory glassware – One mark 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, Rubber, raw, natural and synthetic – Sampling and further preparative procedures

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
© ISO 2009 – All rights reserved 1
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ISO/DIS 11853
3.1
natural rubber 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 rubber

natural rubber usually in bales or packages, forming the starting material for the manufacturing of rubber

articles
3.3
magnesium content

content of magnesium present in a sample of natural rubber latex concentrate, and in all forms of raw natural

rubber and rubber product
4 Principle

A test portion is ashed at 550 ºC ± 25 ºC. The ash is dissolved in 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-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.
a) Nitric acid (density = 1.41 mg/m );
3 3

b) Dilute nitric acid (1.6% v/v) by carefully pipette 11,5 cm of the nitric acid (5.a) into a 1000 cm one-mark

volumetric flask (6.4) and dilute to the mark with distilled water or water of equivalent purity;

c) Standard magnesium stock solution, containing 1 g of Mg per cubic decimetre; Use a commercially

available standard magnesium solution.

d) Standard magnesium solution, containing 10 mg of Mg per cubic decimetre. Carefully pipette 10 cm

of the standard magnesium stock solution (5.c) into a 1000 cm one-mark volumetric flask (6.4) dilute to

the mark with dilute nitric acid (5.b) and mix thoroughly. Prepare this solution preferably on the day of use.

1 cm of this standard stock solution contains 10 µg of Mg.
6 Apparatus

6.1 Atomic absorption spectrometer, fitted with a burner fed with acetylene and air compressor 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 operated in accordance with the manufacturer’s 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 ºC ± 25 ºC.

3 3 3 3 3

6.4 One-mark volumetric flasks, glass-stopper, of capacities 25 cm , 50 cm , 100 cm , 200 cm , 500 cm

and 1000 cm , complying with the requirem
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