Magnesium lithium alloys -- Determination of lithium -- Inductively coupled plasma optical emission spectrometric method

This document specifies a method for the determination of lithium contents in magnesium lithium alloys by inductively coupled plasma (ICP) optical emission spectrometry. The method is applicable to the determination of lithium content between 3,0 % and 16,0 % (mass fraction) in magnesium lithium alloys.

Alliages de magnésium -- Détermination de lithium

General Information

Status
Published
Publication Date
09-Aug-2018
Current Stage
6060 - International Standard published
Start Date
20-Jul-2018
Completion Date
10-Aug-2018
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ISO 20258:2018 - Magnesium lithium alloys -- Determination of lithium -- Inductively coupled plasma optical emission spectrometric method
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INTERNATIONAL ISO
STANDARD 20258
First edition
2018-08
Magnesium lithium alloys —
Determination of lithium —
Inductively coupled plasma optical
emission spectrometric method
Reference number
ISO 20258:2018(E)
ISO 2018
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ISO 20258:2018(E)
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© ISO 2018

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ii © ISO 2018 – All rights reserved
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ISO 20258:2018(E)
Contents Page

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

Introduction ..................................................................................................................................................................................................................................v

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

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

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

4 Principle ........................................................................................................................................................................................................................ 1

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

6 Apparatus ..................................................................................................................................................................................................................... 2

7 Sampling and sample preparation .................................................................................................................................................... 3

8 Procedure..................................................................................................................................................................................................................... 3

8.1 General ........................................................................................................................................................................................................... 3

8.2 Test portion ................................................................................................................................................................................................ 4

8.3 Determination ......................................................................................................................................................................................... 4

8.3.1 Preparation of the test solution .......................................................................................................................... 4

8.3.2 Preparation of the calibration solutions ...................................................................................................... 4

8.4 Adjustment of the apparatus ...................................................................................................................................................... 4

8.5 Measurement of the calibration solutions ...................................................................................................................... 4

8.6 Calibration curve ................................................................................................................................................................................... 5

8.7 Measurements of the test solution ........................................................................................................................................ 5

9 Expression of results ........................................................................................................................................................................................ 5

9.1 Method of calculation ........................................................................................................................................................................ 5

9.2 Precision ....................................................................................................................................................................................................... 5

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

Annex A (normative) Inductively coupled plasma optical emission spectrometer —

Performance criteria to be checked ................................................................................................................................................. 7

Annex B (informative) Information on the precision test .............................................................................................................. 9

Annex C (informative) Graphical representation of precision data ..................................................................................10

Bibliography .............................................................................................................................................................................................................................11

© ISO 2018 – All rights reserved iii
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ISO 20258:2018(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

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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).

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.org/iso/foreword .html.

This document was prepared by Technical Committee ISO/TC 79, Light metals and their alloys,

Subcommittee SC 5, Magnesium and alloys of cast or wrought magnesium.

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 2018 – All rights reserved
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ISO 20258:2018(E)
Introduction

Magnesium lithium alloys are the lightest metallic materials in the world and show several

advantageous properties such as: excellent rigidity, high electric and thermal conductivity, good

damping, electromagnetic, shielding, welding, matching and cold forming performances. Lithium is the

most important element in magnesium lithium alloys, and can improve the deformation capability of

alloys with further a decrease in weight. With the increasing demands of the world today for lightweight

materials, energy saving, environmental protection and sustainable development, magnesium lithium

alloys show broad application prospects in the fields of materials, transportation, electronics, medical

products and so on.

Chemical compositions of magnesium and its alloys are widely standardized from major to trace

contents in international and other national standards. However, there is no standard dealing with the

determination of lithium content in magnesium lithium alloys.
© ISO 2018 – All rights reserved v
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INTERNATIONAL STANDARD ISO 20258:2018(E)
Magnesium lithium alloys — Determination of lithium
— Inductively coupled plasma optical emission
spectrometric method
1 Scope

This document specifies a method for the determination of lithium contents in magnesium lithium

alloys by inductively coupled plasma (ICP) optical emission spectrometry.

The method is applicable to the determination of lithium content between 3,0 % and 16,0 % (mass

fraction) in magnesium lithium alloys.
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 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
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/
4 Principle

Dissolution of a test portion in hydrochloric acid. Nebulization of the solution into an ICP optical

emission spectrometer and measurement of the intensity of the emitted light from lithium.

Calibration based on a very close matrix matching of the calibration solutions to the sample shall be

carried out. The advantage with this procedure is that all possible interferences from the matrix will be

compensated, which will result in high accuracy. This is important to spectral interferences, which can

be severe in highly alloyed matrixes.

All spectral interferences shall be kept at a minimum level. Therefore, it is essential to select the

appropriate wavelengths. The wavelengths generally used for lithium are shown in Table 1 together

with the possible interferences. Depending on the performance of each spectrometer, other wavelengths

may be used, provided that interferences, sensitivity, resolution and linearity criteria have been

carefully investigated.
© ISO 2018 – All rights reserved 1
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ISO 20258:2018(E)
5 Reagents

During the analysis, use only reagents of recognized analytical grade and only grade 2 water as

specified in ISO 3696, or water of equivalent purity.
5.1 Pure magnesium, purity ≥ 99,99 % (mass fraction), free from lithium.
5.2 Lithium carbonate, purity ≥ 99,99 % (mass fraction).
5.3 Hydrochloric acid, ρ about 1,19 g/ml.

5.4 Hydrochloric acid solution 1 + 1, add 500 ml of hydrochloric acid (5.3) to 500 ml of water.

5.5 Hydrogen peroxide, ρ about 1,13 g/ml.
5.6 Magnesium base solution, corresponding to 2,5 g of magnesium per litre.

Weigh, to the nearest of 1 mg, 0,5 g of pure magnesium (5.1) and transfer into a 300 ml glass beaker.

Add about 50 ml of water and, in small portions, 25 ml of hydrochloric acid (5.4). Cover with a watch-

glass and, if necessary, heat gently to complete the dissolution. Add a few drops of hydrogen peroxide

(5.5) and boil for 5 min. Cool and transfer quantitatively into a 200 ml one-mark volumetric flask. Dilute

to the mark with water and mix.
1 ml of this solution contains 2,5 mg of magnesium.
5.7 Magnesium base solution, corresponding to 0,25 g of magnesium per litre.
Transfer 10 ml of the solution (5.6) to a 100 m
...

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