IEC TR 63025:2021

IEC TR 63025 ®
Edition 1.0 2021-07
TECHNICAL
REPORT
colour
inside
Insulating liquids – Quantitative determination of methanol and ethanol in
insulating liquids
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IEC TR 63025 ®
Edition 1.0 2021-07
TECHNICAL
REPORT
colour
inside
Insulating liquids – Quantitative determination of methanol and ethanol in

insulating liquids
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.040.10 ISBN 978-2-8322-9990-6

– 2 – IEC TR 63025:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Symbols and abbreviated terms . 9
5 Sampling . 10
6 Principle of the methods . 10
7 Method A – HS-GC-MS . 10
7.1 General . 10
7.2 Apparatus . 10
7.2.1 Analytical balance . 10
7.2.2 Headspace sampler . 10
7.2.3 Gas chromatograph coupled with mass spectrometry detector . 11
7.3 Reagents and materials . 11
7.3.1 Laboratory equipment and glassware . 11
7.3.2 Standard chemicals . 11
7.3.3 GC carrier gases . 12
7.4 Preparation of standard solutions . 12
7.4.1 General . 12
7.4.2 Degassed insulating liquid . 12
7.4.3 Internal standard stock solution . 12
7.4.4 Standard solutions of methanol and ethanol . 13
7.5 Sample preparation . 14
7.6 Headspace sampler parameters . 15
7.7 Gas chromatograph parameters . 15
7.7.1 Injector . 15
7.7.2 Carrier gas . 15
7.7.3 Temperature ramp . 15
7.8 Mass spectrometer parameters . 16
7.9 Analysis procedure . 16
7.10 Internal standard calibration . 17
7.10.1 General . 17
7.10.2 Response factor determination . 18
7.11 Expression of the results . 18
8 Method B – HS-GC-FID . 18
8.1 General . 18
8.2 Apparatus . 18
8.2.1 Analytical balance . 18
8.2.2 Headspace sampler . 18
8.2.3 Gas chromatograph with flame ionization detector . 19
8.3 Reagents and materials . 19
8.3.1 Laboratory equipment and glassware . 19
8.3.2 Standard chemicals . 19
8.3.3 GC carrier gases . 19
8.4 Preparation of standard solutions . 20

8.4.1 General . 20
8.4.2 Degassed insulating liquid . 20
8.4.3 Standard solutions of methanol and ethanol . 20
8.5 Sample preparation . 21
8.6 Headspace sampler parameters . 21
8.7 Gas chromatograph parameters . 22
8.7.1 Injector . 22
8.7.2 Carrier gas . 22
8.7.3 Temperature ramp . 22
8.7.4 FID parameters . 22
8.8 Analysis procedure . 22
8.9 Calibration . 23
8.10 Expression of the results . 23
9 Test report . 23
10 Precision . 24
10.1 Verification of the entire analytical system . 24
10.2 General . 24
10.3 Detection limits of Method A and Method B . 24
10.4 Repeatability . 24
10.5 Reproducibility . 25
Bibliography . 26

Figure 1 – Comparison of methanol and 2-furfural production in mineral oil versus
cellulose scission number . 7
Figure 2 –Typical chromatogram with selected ion (m/z = 31) mass spectrum . 17
Figure 3 – Typical GC-FID chromatogram . 23

Table 1 –Method A – Example of GC temperature ramp parameters . 16
Table 2 – Method A – m/z values of internal standard ions . 16
Table 3 – Method B – Examples of FID parameters reported in literature . 22
Table 4 – Detection limits of Method A and Method B, in mineral oil . 24
Table 5 – Repeatability (r) in % for Method A (HS-GC-MS), in mineral oil . 24
Table 6 – Reproducibility (R) in % for Method A (HS-GC-MS), in mineral oil . 25

– 4 – IEC TR 63025:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATING LIQUIDS – QUANTITATIVE DETERMINATION OF
METHANOL AND ETHANOL IN INSULATING LIQUIDS

FOREWORD
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