IEC TS 62607-6-20:2022

Nanomanufacturing - Key control characteristics - Part 6-20: Graphene-based material - Metallic impurity content: Inductively coupled plasma mass spectrometry

IEC TS 62607-6-20:2022 (EN) IEC TS 62607 establishes a standardized method to determine the chemical key control characteristic
- metallic impurity content
for powders of graphene-based materials by
- inductively coupled plasma mass spectrometry (ICP-MS).
The metallic impurity content is derived by the signal intensity of measured elements through MS spectrum of ICP-MS.
- The method is applicable for powder of graphene and related materials, including bilayer graphene (2LG), trilayer graphene (3LG), few-layer graphene (FLG), reduced graphene oxide (rGO) and graphene oxide (GO).
– The typical application area is in the microelectronics industry, e.g. conductive pastes, displays, etc., for manufacturers to guide material design, and for downstream users to select suitable products.

General Information

• Status: Published
• Publication Date: 10-Oct-2022
• ICS: 07.120 - Nanotechnologies
• Technical Committee: TC 113 - Nanotechnology for electrotechnical products and systems
• Drafting Committee: WG 8 - TC 113/WG 8
• Current Stage: PPUB - Publication issued
• Start Date: 08-Nov-2022
• Completion Date: 11-Oct-2022

Standards Content (Sample)

IEC TS 62607-6-20
®

Edition 1.0 2022-10
TECHNICAL
SPECIFICATION

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Nanomanufacturing – Key control characteristics –
Part 6-20: Graphene-based material – Metallic impurity content: Inductively
coupled plasma mass spectrometry
IEC TS 62607-6-20:2022-10(en)

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IEC TS 62607-6-20

®


Edition 1.0 2022-10




TECHNICAL



SPECIFICATION








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Nanomanufacturing – Key control characteristics –

Part 6-20: Graphene-based material – Metallic impurity content: Inductively

coupled plasma mass spectrometry

























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ICS 07.120 ISBN 978-2-8322-5732-6




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CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 General terms . 7
3.2 Key control characteristics measured in accordance with this document . 9
4 General . 9
4.1 Chemical reagents . 9
4.2 Description of measurement instrument and apparatus . 9
4.2.1 Measurement instrument . 9
4.2.2 Sample pre-treatment apparatus . 9
4.2.3 Other . 9
4.3 Calibration standards . 10
4.3.1 Standard stock solutions . 10
4.3.2 Internal standard (IS) solutions . 10
5 Sample preparation method . 10
5.1 General . 10
5.2 Sample pre-treatment procedure . 10
6 Measurement procedure . 12
6.1 Calibration of ICP-MS instrument . 12
6.2 Quantitative measurement procedure . 12
6.2.1 Whole element scanning . 12
6.2.2 Quantitative measurement of metal impurities. 12
6.2.3 Method recovery measurement . 12
6.2.4 Standard recovery measurement . 12
7 Data analysis . 13
7.1 Content of metal impurities in test samples . 13
7.2 Standard recovery. 13
8 Measurement uncertainty estimation. 13
9 Measurement report . 14
9.1 General . 14
9.2 Product or sample identification . 14
9.3 Measurement conditions . 14
9.4 Measurement specific information . 14
9.5 Measurement results . 14
Annex A (informative) Case study for FLG powder . 16
A.1 Test sample . 16
A.2 Sample pre-treatment . 16
A.3 Instrument information . 16
A.4 Standard calibration curve . 16
A.4.1 Standard stock solutions . 16
A.4.2 Standard calibration curve . 17
A.5 Measurement procedure . 17
A.6 Measurement results . 17
Annex B (informative) Case study for rGO powder . 19

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IEC TS 62607-6-20:2022 © IEC 2022 – 3 –
B.1 Test sample . 19
B.2 Sample pre-treatment . 19
B.3 Measurement instrument . 19
B.4 Standard calibration curve . 19
B.5 Measurement results . 21
B.6 Standard recovery. 22
Annex C (informative) Comparison of different pre-treatment methods . 24
C.1 Test sample . 24
C.2 Comparison of different pre-treatment methods. 24
C.2.1 GO test sample preparation . 24
C.2.2 rGO test sample preparation . 25
C.3 Comparison of different digestion conditions . 25
Annex D (informative) Results comparison of ICP-MS and ICP-OES . 27
D.1 Test sample . 27
D.2 Measurement results comparison between ICP-MS and ICP-OES . 27
Bibliography . 28

Figure A.1 – Content distribution of metal impurities detected in FLG test sample . 18
Figure B.1 – Standard calibration curves of several metal elements contained in rGO

test sample . 20
Figure B.2 – Content distribution of metal impurities detected in rGO test sample . 22
Figure B.3 – Standard recovery of most species of metal impurities in rGO test sample . 23
Figure C.1 – Result comparison of three pre-treatment methods for industrial GO
powder . 25
Figure C.2 – Result comparison of different digestion methods for industrial rGO
powder . 25
Figure C.3 – Content of metal impurities detected in rGO test sample using microwave-

assisted digestion under different digestion conditions . 26

Table 1 – Potential interferences for several typical elements in industrial graphene
powder . 12
Table A.1 – Content of all metal impurities detected in FLG test sample . 17
Table B.1 – Content of all metal impurities detected in rGO test sample . 21
Table D.1 – Measurement results comparison between ICP-MS and ICP-OES . 27

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

NANOMANUFACTURING – KEY CONTROL CHARACTERISTICS –

Part 6-20: Graphene-based material – Metallic impurity content:
Inductively coupled plasma mass spectrometry

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TS 62607-6-20 has been prepared by IEC technical committee 113: Nanotechnology for
electrotechnical products and systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
113/609/DTS 113/629/RVDTS

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

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IEC TS 62607-6-20:2022 © IEC 2022 – 5 –
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
A list of all parts of the IEC TS 62607 series, published under the general title
Nanomanufacturing – Key control characteristics, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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– 6 – IEC TS 62607-6-20:2022 © IEC 2022
INTRODUCTION
Graphene-based materials have wide potential applications because of their unique electrical,
thermal and mechanical properties, especially in the electronics industry: batteries, integrated
1
circuits, high-frequency electronics, displays, etc. [1], [2], [3] . As industry uptake on graphene-
based materials increases, international standardization is critical to enable the
commercialization of graphene-based materials and related products. Metal impurities within
graphene-based materials have significant impact on the electrical performance in the process
of industrial application. Considering the multiple production routes and producers of graphene-
based materials, in order to maintain product quality and reach a consensus between the
supplier and the customer, there is no doubt that accurate, reliable and reproducible
measurement methods for the key parameters of graphene-based materials need to be
established.
Inductively coupled plasma mass spectrometry (ICP-MS) can carry out accurate detection of
trace amounts of a variety of metal impurities simultaneously, obtain species and content of
each metal impurity in graphene-based materials.
The purpose of this document is to enable accurate and quantitative determination of metal
impurities using ICP-MS [4], through providing optimized digestion operation, preparation
procedures for graphene-based materials in powder form, measurement method and data
analysis. A similar document was published as ISO/TS 13278 for carbon nanotubes (CNTs) [5];
however, it is not suitable for graphene powder because of the noticeable difference between
CNTs and graphene powder, especially in terms of sample preparation (including digestion
technique and digestion procedure), the properties of test samples (many more species and
much wider range of content of metal impurities in graphene powder), measurement procedure
and so on. Therefore, this document has been developed for graphene powder; it is based on
study in VAMAS Technical Working Area 41 (TWA 41).


___________
1
 Numbers in square brackets refer to the Bibliography.

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IEC TS 62607-6-20:2022 © IEC 2022 – 7 –
NANOMANUFACTURING – KEY CONTROL CHARACTERISTICS –

Part 6-20: Graphene-based material – Metallic impurity content:
Inductively coupled plasma mass spectrometry
h
1 Scope
This part of IEC TS 62607 establishes a standardized method to determine the chemical key
control characteristic
– metallic impurity content
for powders of graphene-based materials by
– inductively coupled plasma mass spectrometry (ICP-MS).
The metallic impurity content is derived by the signal intensity of measured elements through
MS spectrum of ICP-MS.
– The method is applicable for powder of graphene and related materials, including bilayer
graphene (2LG), trilayer graphene (3LG), few-layer graphene (FLG), reduced graphene
oxide (rGO) and graphene oxide (GO).
– The typical application area is in the microelectronics industry, e.g. conductive pastes,
displays, etc., for manufacturers to guide material design, and for downstream users to
select suitable products.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 General terms
3.1.1
graphene
graphene layer
single-layer graphene
monolayer graphene
single layer of carbon atoms with each atom bound to three neighbours in a honeycomb
structure
Note 1 to entry: It is an important building block of many carbon nano-objects.
Note 2 to entry: As graphene is a single layer, it is also sometimes called monolayer graphene or single-layer
graphene and abbreviated as 1LG to distinguish it from bilayer graphene (2LG) and few-layer graphene (FLG).
Note 3 to entry: Graphene has edges and can have defects and grain boundaries where the bonding is disrupted.
[SOURCE: ISO/TS 80004-13:2017 [6], 3.1.2.1]

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3.1.2
graphene-based material
GBM
graphene material
grouping of carbon-based 2D materials that include one or more of graphene, bilayer graphene,
few-layer graphene, graphene nanoplate and functionalized variations thereof as well as
graphene oxide and reduced graphene oxide
Note 1 to entry: "Graphene material" is a short name for graphene-based material.
3.1.3
bilayer graphene
2LG
two-dimensional material consisting of two well-defined stacked graphene layers
Note 1 to entry: If the stacking registry is known, it can be specified separately, for example, as "Bernal stacked
bilayer graphene".
[SOURCE: ISO/TS 80004-13:2017 [6], 3.1.2.6]
3.1.4
trilayer graphene
3LG
two-dimensional material consisting of three well-defined stacked graphene layers
Note 1 to entry: If the stacking registry is known, it can be specified separately, for example, as "twisted trilayer
graphene".
[SOURCE: ISO/TS 80004-13:2017 [6], 3.1.2.9]
3.1.5
few-layer graphene
FLG
two-dimensional material consisting of three to ten well-defined stacked graphene layers
[SOURCE: ISO/TS 80004-13:2017 [6], 3.1.2.10]
3.1.6
graphene oxide
GO
chemically modified graphene prepared by oxidation and exfoliation of graphite, causing
extensive oxidative modification of the basal plane
Note 1 to entry: Graphene oxide is a single-layer material with a high oxygen content, typically characterized by
C/O atomic ratios of approximately 2,0 depending on the method of synthesis.
[SOURCE: ISO/TS 80004-13:2017 [6], 3.1.2.13]
3.1.7
reduced graphene oxide
rGO
reduced oxygen content form of graphene oxide
Note 1 to entry: rGO can be produced by chemical, thermal, microwave, photo-chemical, photo-thermal, microbial
or bacterial methods, or by exfoliating reduced graphite oxide.
Note 2 to entry: If graphene oxide was fully reduced, then graphene would be the product. However, in practice,
3 2
some oxygen containing functional groups will remain and not all sp bonds will return back to sp configuration.
Different reducing agents will lead to different carbon to oxygen ratios and different chemical compositions in reduced
graphene oxide.
Note 3 to entry: It can take the form of several morphological variations such as platelets and worm-like structures.

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IEC TS 62607-6-20:2022 © IEC 2022 – 9 –
[SOURCE: ISO/TS 80004-13:2017 [6], 3.1.2.14]
3.2 Key control characteristics measured in accordance with this document
3.2.1
metallic impurity
metallic element present in graphene-based materials and not in the crystalline structure of
graphene
Note 1 to entry: The content of most metallic impurities in graphene-based materials is usually trace, but for
industrial products of graphene powder, the content of a few metal impurities can be higher, e.g. Na element coming
from water used in rGO production, and Cu or Fe element coming from manufacturing equipment used in the
production of FLG powder.
4 General
4.1 Chemical reagents
All reagents should be guaranteed reagents (GRs) at least, and the purity quotient should be
no less than 99,99 %.
4.1.1 Ultra-pure nitric acid (HNO , MOS (metal-oxide-semiconductor) or higher, 70 %
3
mass fraction), which is used as digestion solvent of graphene powder, to make up the control
test sample, and blank solution for instrument self-checking and cleaning.
4.1.2 Hydrofluoric acid (HF, MOS or higher, 40% mass fraction), when necessary (e.g. Si
or Ti element is a little higher in content), as a digestion solution together with nitric acid.
However, HF is powerfully corrosive, and working with HF requires special precautions to avoid
contact with skin. All operation should be carried out in fume hood with safe protection such as
rubber gloves and work clothes, etc.
4.1.3 Ultra-pure water used as diluted solvent.
4.2 Description of measurement instrument and apparatus
4.2.1 Measurement instrument
ICP-MS should be used to measure metal impurities in graphene powder. ICP-MS instrument
can be equipped with a quadrupole or sector field mass spectrometer, or another type of
ICP-MS instrument operating with at least 1u (atomic mass unit) resolution for multi-elements
determination.
4.2.2 Sample pre-treatment apparatus
4.2.2.1 Microwave digester used for digestion of graphene powder immersed in digestive
solvent.
4.2.2.2 Pressure tank (acid proof and high temperature resistance) also used for digestion.
The tank should be placed in an oven over 200 °C for more than 6 h.
4.2.2.3 Acid-driven processor used for acid-driving of the test samples after digestion.
4.2.3 Other
4.2.3.1 Static discharge gun used to neutralize the static charge while graphene powder
is being weighed and transferred.
4.2.3.2 Analytical balance with a resolution of 0,000 1 g.

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4.2.3.3 100 µL, 1 000 µL, 5 mL pipettes used to transfer liquid.
4.2.3.4 10 mL, 25 mL, 50 mL volumetric flasks used for constant volume.
4.2.3.5 10 mL, 15 mL, 50 mL, 100 mL centrifuge tubes used as container.
4.3 Calibration standards
4.3.1 Standard stock solutions
There are approximately 20 to 30 kinds of metal impurities in industrial graphene powder, so
mixed standard solutions including Fe, Cr, Mn, W, Ti, Mo, Zn, Ni, Rb, Zr, Sr, Sb, Sn, Co, Pb,
Ce, Ba, and Cu elements, etc, are recommended.
It is recommended to use simultaneously four kinds of mixed standard solution (available from
commercial vendors), such as, but not limited to, the following.
a) Multi-element Solution No. 1: Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, In, K,
Li, Mg, Mn, Na, Ni, Pb, Rb, Se, Sr, Tl, U, V, and Zn.
b) Multi-element Solution No. 2: Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sc, Sm, Tb, Th, Tm,
Y, and Yb.
c) Multi-element Solution No. 3: Au, Hf, Hg, Ir, Pd, Pt, Rh, Ru, Sb, Sn, and Te.
d) Multi-element Solution No. 4: B, Ge, Mo, Nb, P, Re, S, Si, Ta, Ti, W, and Zr.
4.3.2 Internal standard (IS) solutions
Single-element internal standard (IS) solutions are available from commercial vendors.
Alternatively, IS stock solutions can be prepared in-house giving due consideration to the purity
of water and acids. Li, Sc, Ge, Y, Rh, In, Tb, Lu, Re, Bi, etc. are usually used as IS elements.
Prior to quantitative analysis, a preliminary scan should be conducted to select suitable IS
elements.
The selection of IS elements should fulfil four criteria.
a) The IS element is not present in the test sample.
b) The IS element has similar molecular weight and ionization energy to the analytical element.
c) The IS element is not disturbed easily by other elements.
d) The signal intensity of the IS element is not affected by count statistics, that is, the
concentration of the IS element is sufficiently high.
5 Sample preparation method
5.1 General
For the test sample of graphene powder, four to six parallel specimens should be treated
simultaneously. According to the content of metal impurities measured, the standard recovery
of several key elements should be measured, by adding the standard solution of metal elements
selected into test specimens prior to digestion; at least two parallel specimens shall be prepared
for spiked specimens.
5.2 Sample pre-treatment procedure
The pre-treatment procedure is as follows.
1) Select several PTFE digestion vessels, according to the microwave digester used and the
number of parallel test specimens, spiked samples and cont
...