Rubber — Determination of metal content by atomic absorption spectrometry — Part 2: Determination of lead content

This document specifies an atomic absorption spectrometric 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 can be determined, provided that suitable adjustments are made to the mass of the test portion and/or the concentration of the solutions used. The use of the standard-additions method might lower the bottom limit of detection.

Caoutchouc — Détermination de la teneur en métal par spectrométrie d'absorption atomique — Partie 2: Dosage du plomb

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Status
Published
Publication Date
28-Nov-2019
Current Stage
6060 - International Standard published
Start Date
29-Nov-2019
Completion Date
29-Nov-2019
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INTERNATIONAL ISO
STANDARD 6101-2
Third edition
2019-11
Rubber — Determination of metal
content by atomic absorption
spectrometry —
Part 2:
Determination of lead content
Caoutchouc — Détermination de la teneur en métal par
spectrométrie d'absorption atomique —
Partie 2: Dosage du plomb
Reference number
ISO 6101-2:2019(E)
ISO 2019
---------------------- Page: 1 ----------------------
ISO 6101-2:2019(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2019

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 2019 – All rights reserved
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ISO 6101-2:2019(E)
Contents Page

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

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

2 Normative references ...................................................................................................................................................................................... 1

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

4 Principle ........................................................................................................................................................................................................................ 2

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus ..................................................................................................................................................................................................................... 3

7 Sampling ........................................................................................................................................................................................................................ 3

8 Procedure..................................................................................................................................................................................................................... 4

8.1 Test portion ................................................................................................................................................................................................ 4

8.2 Preparation of test solution ......................................................................................................................................................... 4

8.2.1 Destruction of organic matter .............................................................................................................................. 4

8.2.2 Dissolution of inorganic residue ........................................................................................................................ 4

8.3 Preparation of the calibration graph .................................................................................................................................... 5

8.3.1 Preparation of calibration solutions ............................................................................................................... 5

8.3.2 Spectrometric measurements .............................................................................................................................. 5

8.3.3 Plotting the calibration graph ............................................................................................................................... 5

8.4 Determination ......................................................................................................................................................................................... 5

8.4.1 Spectrometric measurements .............................................................................................................................. 5

8.4.2 Dilution..................................................................................................................................................................................... 6

8.5 Blank determination .......................................................................................................................................................................... 6

8.6 Number of determinations ........................................................................................................................................................... 6

9 Expression of results ........................................................................................................................................................................................ 6

10 Test report ................................................................................................................................................................................................................... 7

Annex A (informative) Method of standard additions ........................................................................................................................ 9

© ISO 2019 – All rights reserved iii
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ISO 6101-2:2019(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 of 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 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 6101-2:1997), of which it constitutes

a minor revision to update normative references in Clause 2.
A list of all parts in the ISO 6101 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2019 – All rights reserved
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INTERNATIONAL STANDARD ISO 6101-2:2019(E)
Rubber — Determination of metal content by atomic
absorption spectrometry —
Part 2:
Determination of lead content

WARNING 1 — Persons using this document should be familiar with normal laboratory practice.

This document 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

determine the applicability of any other restrictions.

WARNING 2 — Certain procedures specified in this document 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 handling and disposal after use.

1 Scope

This document specifies an atomic absorption spectrometric 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 can be determined, provided that suitable

adjustments are made to the mass of the test portion and/or the concentration of the solutions used.

The use of the standard-additions method might lower the bottom limit of detection.

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 247-1:2018, Rubber — Determination of ash — Part 1: Combustion method
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 1772, Laboratory crucibles in porcelain and silica

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:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
© ISO 2019 – All rights reserved 1
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ISO 6101-2:2019(E)
4 Principle

If the rubber does not contain halogenated compounds, a test portion is directly ashed at 550 °C ± 25 °C

as specified in ISO 247-1:2018, method A. If the rubber contains halogenated compounds, a test portion

is first mineralized with sulfuric and nitric acids, the acids are removed by evaporation, and the portion

is ashed at 550 °C ± 25 °C.

NOTE The presence of even small amounts of halogens can lead to the loss of volatile lead salts during

dry ashing.

The ash obtained is boiled with 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

wavelength of 283,3 nm, using a lead hollow-cathode lamp as the lead 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 Sulfuric acid, ρ = 1,84 Mg/m .
5.2 Nitric acid, ρ = 1,40 Mg/m .
5.3 Hydrochloric acid, ρ = 1,18 Mg/m .
5.4 Hydrochloric acid, diluted 1 + 2.
Dilute 1 volume of concentrated hydrochloric acid (5.3) with 2 volumes of water.
5.5 Hydrogen peroxide, 30 % (mass fraction) solution.
5.6 Ammonium acetate, 180 g/dm solution.
5.7 Standard lead stock solution, containing 1 g of Pb per cubic decimetre.

Either use a commercially available standard lead solution, or prepare as follows:

Weigh, to the nearest 0,1 mg, 1 g of metallic lead (purity ≥ 99,95 %) and transfer to a 100 cm beaker

3 3

(6.12). Add 30 cm of water and 20 cm of nitric acid (5.2) and boil on a sand bath (6.10). If the lead is

dissolved, continue boiling until the solution is reduced to about 20 cm or less. No nitrogen oxides

should be observed. Otherwise, add water and continue boiling. Transfer to a 1 000 cm one-mark

volumetric flask (see 6.7) with 1 + 2 hydrochloric acid (5.4) and fill to the mark with 1 + 2 hydrochloric

acid (5.4).
1 cm of this standard stock solution contains 1 mg of Pb.
5.8 Standard lead solution, containing 10 mg of Pb per cubic decimetre.

Using a pipette (6.9), carefully introduce 10 cm of the standard lead stock solution (5.7) into a

1 000 cm one-mark volumetric flask (see 6.7). Dilute to the mark with 1 + 2 hydrochloric acid (5.4),

and mix thoroughly.
Prepare this solution on the day of use.
1 cm of this standard solution contains 10 μg of Pb.
2 © ISO 2019 – All rights reserved
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