ISO 6101-5:2018

Rubber — Determination of metal content by atomic absorption spectrometry — Part 5: Determination of iron content

This document specifies an atomic absorption spectrometric method for the determination of the iron content of rubbers. The method is applicable to raw rubber, rubber products and latex having iron contents of 5 mg/kg to 1 000 mg/kg. Higher concentrations can be determined, provided that suitable adjustments are made to the mass of the test portion and/or the concentrations of the solution used.

Caoutchouc — Dosage du métal par spectrométrie d'absorption atomique — Partie 5: Dosage du fer

General Information

• Status: Published
• Publication Date: 30-Jul-2018
• ICS: 83.060 - Rubber
• Technical Committee: ISO/TC 45/SC 2 - Testing and analysis
• Drafting Committee: ISO/TC 45/SC 2/WG 5 - Chemical tests
• Current Stage: 9060 - Close of review
• Start Date: 02-Dec-2028

Relations

• Revises: ISO 6101-5:2006 - Rubber — Determination of metal content by atomic absorption spectrometry — Part 5: Determination of iron content
• Effective Date: 05-Nov-2015

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 6101-5
Third edition
2018-07
Rubber — Determination of metal
content by atomic absorption
spectrometry —
Part 5:
Determination of iron content
Caoutchouc — Dosage du métal par spectrométrie d'absorption
atomique —
Partie 5: Dosage du fer
Reference number
ISO 6101-5:2018(E)
©
ISO 2018

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ISO 6101-5:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2018 – All rights reserved

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ISO 6101-5:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 2
7 Sampling . 3
8 Procedure. 3
8.1 Preparation of test portion . 3
8.2 Preparation of test solution . 4
8.2.1 Destruction of organic matter . 4
8.2.2 Dissolution of inorganic residue using hydrochloric acid . 4
8.2.3 Dissolution of inorganic residue using nitric acid — Alternative method . 4
8.3 Preparation of the calibration curves . 4
8.3.1 Preparation of standard calibration solutions . 4
8.3.2 Spectrometric measurements . 5
8.3.3 Plotting the calibration curves . 5
8.4 Determination . 5
8.4.1 Spectrometric measurements . 5
8.4.2 Dilution. 6
8.4.3 Blank determination . 6
8.4.4 Number of determinations. 6
9 Expression of results . 6
10 Precision . 7
11 Test report . 7
Annex A (informative) Method of standard addition . 8
Annex B (informative) Precision .10
Bibliography .11
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ISO 6101-5:2018(E)

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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analysis.
This third edition cancels and replaces the second edition (ISO 6101-5:2006), which has been technically
revised as follows:
— nitric acid has been added as a digestion acid;
— the concentration for sulphuric acid has been specified;
— the procedure for the destruction of organic matter has been further detailed;
— the volume for final solution following dissolution using hydrochloric acid (8.2.2) has been changed
3
to 50 cm to ensure consistency of the formulae used throughout the ISO 6101 series;
— Formulae 1 and 2 in Clause 9 have been corrected for the iron content expressed as percentage by
mass and milligram per kilogram, respectively;
— Annex A and Annex B have been added to include method of standard addition and precision
statement of the method.
A list of all parts in the ISO 6101 series can be found on the ISO website.
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INTERNATIONAL STANDARD ISO 6101-5:2018(E)
Rubber — Determination of metal content by atomic
absorption spectrometry —
Part 5:
Determination of iron content
1 Scope
This document specifies an atomic absorption spectrometric method for the determination of the iron
content of rubbers.
The method is applicable to raw rubber, rubber products and latex having iron contents of 5 mg/kg to
1 000 mg/kg. Higher concentrations can be determined, provided that suitable adjustments are made
to the mass of the test portion and/or the concentrations of the solution used.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 total solids content
ISO 247-1, Rubber — Determination of ash — Combustion method
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp/
4 Principle
A test portion is ashed at 550 °C ± 25 °C in accordance with ISO 247-1. The ash is dissolved in hydrochloric
acid or nitric acid and if any silicates are present they are decomposed with a mixture of sulfuric acid
and hydrofluoric acid to remove them.
The solution obtained is aspirated into an atomic absorption spectrometer and the absorption is
measured at a wavelength of 248,3 nm for concentrations up to 10 mg/kg or 0,001 % (by mass), or
372,0 nm for concentrations of 10 mg/kg to 1 000 mg/kg or 0,001 % (by mass) to 0,1 % (by mass).
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ISO 6101-5:2018(E)

5 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade, and only
distilled water or water of equivalent purity.
3
5.1 Sulfuric acid, ρ = 1,84 Mg/m , 95 % (m/m) to 97 % (m/m).
20
3
5.2 Hydrochloric acid, ρ = 1,19 Mg/m , 37 % (m/m).
20
5.3 Hydrochloric acid diluted 1 + 3, dilute 1 volume of concentrated hydrochloric acid (5.2) with
3 volumes of water.
3
5.4 Hydrofluoric acid, ρ = 1,13 Mg/m , 38 % (m/m) to 48 % (m/m).
20
3
5.5 Concentrated nitric acid, ρ = 1,42 Mg/m , 69 % (m/m).
20
3
5.6 Dilute nitric acid, 1,6 % (by mass), carefully pipette 11,5 cm of concentrated nitric acid (5.5) into
3
a 1 000 cm one-mark volumetric flask, making up to the mark with water, and mix thoroughly.
5.7 Standard iron stock solution, containing 1 g of Fe per cubic decimetre.
Either use a commercially available standard iron solutions, or prepare as follows:
3
Grind metallic iron, purity greater than 99 % (by mass). Weigh 1 g to the nearest 0,1 mg in a 250 cm
3 3
conical flask (6.11) and dissolve it in a mixture of 100 cm of 1 + 3 hydrochloric acid (5.3) and 10 cm of
3
concentrated nitric acid (5.5). Transfer it to a 1 000 cm one-mark volumetric flask (6.4), dilute to the
mark with 1 + 3 hydrochloric acid (5.3) and mix thoroughly.
3
1 cm of this standard solution contains 1 000 μg of Fe.
3
5.8 Standard iron solution, containing 10 mg of Fe per 1 000 cm .
3
Carefully pipette 10 cm of the standard iron stock solution (5.7) using volumetric pipette (6.13) into a
3
1 000 cm one-mark volumetric flask (6.4) and dilute to the mark with 1 + 3 hydrochloric acid (5.3) or
diluted nitric acid (5.6).
3
1 cm of this primary calibration solution contains 10 μg of Fe.
6 Apparatus
Use ordinary laboratory apparatus and the following, ensuring that all apparatus and laboratory
implements are non-ferrous.
6.1 Balance, accurate to 0,1 mg.
6.2 Muffle furnace, capable of being maintained at 550 °C ± 25 °C.
3
6.3 Beaker, of capacity 250 cm .
3 3 3 3
6.4 One-mark volumetric flasks, glass-stoppered, of capacity 50 cm , 100 cm , 200 cm , 500 cm
3
and 1 000 cm , complying with the requirements of ISO 1042, class A.
6.5 Filter funnel.
3
6.6 Crucible (silica or porcelain), of capacity 150 cm depending on the test portion size.
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ISO 6101-5:2018(E)

3 3
6.7 Crucible (platinum), of capacity 50 cm to 150 cm depending on the test portion size.
6.8 Platinum rod or borosilicate-glass rod, as stirrer.
6.9 Ashless filter paper, of diameter 150 mm.
6.10 Electrical heating plate or sand bath.
3
6.11 Conical flask, of capacity 250 cm .
6.12 Atomic absorption spectrometer, fitted with a burner fed with acetylene and compressed air and
also fitted with an iron hollow-cathode lamp capable of emitting radiation of the required wavelengths. A
high-brightness lamp is advisable.
The instrument shall be operated in accordance with the manufacturer's 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 manufacturer's instructions for optimum performance.
3 3 3 3 3
6.13 Volumetric pipettes, of
...