IEC 62697-1:2012

Test methods for quantitative determination of corrosive sulfur compounds in unused and used insulating liquids - Part 1: Test method for quantitative determination of dibenzyldisulfide (DBDS)

IEC 62697-1:2012 specifies a test method for the quantitative determination of corrosive sulfur compounds-dibenzyl disulfide (DBDS) in used and unused insulating liquids over a 5 to 600 mg kg-1 concentration range.

Méthodes d'essai pour la détermination quantitative des composés de soufre corrosif dans les liquides isolants usagés et neufs - Partie 1: Méthode d'essai pour la détermination quantitative du disulfure de dibenzyle (DBDS)

La CEI 62697-1:2012 spécifie une méthode d essai pour la détermination quantitative des composés de soufre corrosif disulfure de dibenzyle (DBDS) dans les liquides isolants usagés et neufs sur une plage de concentration comprise entre 5 mg kg-1 et 600 mg kg-1.

General Information

• Status: Published
• Publication Date: 23-Aug-2012
• ICS: 29.040.01 - Insulating fluids in general
• Technical Committee: TC 10 - Fluids for electrotechnical applications
• Drafting Committee: WG 37 - TC 10/WG 37
• Current Stage: PPUB - Publication issued
• Start Date: 24-Aug-2012
• Completion Date: 15-Sep-2012

Standards Content (Sample)

IEC 62697-1 ®
Edition 1.0 2012-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test methods for quantitative determination of corrosive sulfur compounds in
unused and used insulating liquids –
Part 1: Test method for quantitative determination of dibenzyldisulfide (DBDS)

Méthodes d’essai pour la détermination quantitative des composés de soufre
corrosif dans les liquides isolants usagés et neufs –
Partie 1: Méthode d’essai pour la détermination quantitative du disulfure de
dibenzyle (DBDS)
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IEC 62697-1 ®
Edition 1.0 2012-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Test methods for quantitative determination of corrosive sulfur compounds in

unused and used insulating liquids –

Part 1: Test method for quantitative determination of dibenzyldisulfide (DBDS)

Méthodes d’essai pour la détermination quantitative des composés de soufre

corrosif dans les liquides isolants usagés et neufs –

Partie 1: Méthode d’essai pour la détermination quantitative du disulfure de

dibenzyle (DBDS)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX V
ICS 29.040 ISBN 978-2-83220-305-7

– 2 – 62697-1 © IEC:2012
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 9
2 Normative references . 9
3 Terms, definitions and abbreviations . 9
3.1 Terms and definitions . 9
3.2 Abbreviations . 13
4 Sampling . 13
5 Procedure . 13
5.1 Principle . 13
5.2 Significance and use . 13
5.3 Interferences . 14
5.3.1 Co-eluting compounds . 14
5.3.2 Electron capture detector (ECD) . 14
5.3.3 Atomic emission detector (AED) . 14
5.3.4 Mass spectrometer (MS) . 14
5.3.5 MS/MS . 14
5.3.6 Interference from the matrix . 14
5.4 Apparatus . 15
5.4.1 Balance . 15
5.4.2 Gas chromatography system . 15
5.4.3 Data system . 16
5.5 Reagents and materials . 16
5.5.1 Purity of reagents . 16
5.5.2 Gases . 16
5.5.3 Solvents . 16
5.6 Standard materials . 16
5.6.1 Dibenzyl disulfide (DBDS) . 16
5.6.2 Diphenyl disulfide (DPDS) . 16
5.6.3 Blank oil . 16
5.7 Standard solutions . 17
5.7.1 Stock solution . 17
5.7.2 Internal standard (IS) solution. 17
6 Instrument set-up . 17
6.1 Gas chromatograph . 17
6.1.1 General . 17
6.1.2 Carrier gas . 17
6.1.3 Injector . 17
6.1.4 Separation parameters . 17
6.1.5 ECD detection . 18
6.1.6 AED detection . 18
6.1.7 MS detection . 18
6.1.8 MS/MS detection . 18
6.2 Calibration . 19
6.2.1 General . 19
6.2.2 Calibration procedure . 19

62697-1 © IEC:2012 – 3 –
6.2.3 Response factor determination (ECD and AED) . 19
6.2.4 Response factor determination (MS) . 19
6.2.5 Response factor determination (MS/MS) . 20
6.3 Analysis . 20
6.3.1 Sample pre-treatment . 20
6.3.2 Sample injection . 20
6.3.3 Chromatographic run . 20
6.3.4 Peak integration . 20
6.4 Calculations . 21
6.4.1 ECD and AED . 21
6.4.2 Mass spectrometer (MS) . 21
6.4.3 MS/MS . 21
6.5 Results . 21
7 Precision data . 21
7.1 Detection limit . 21
7.2 Repeatability . 22
7.3 Reproducibility . 22
8 Report . 22
Annex A (informative) Figures with typical chromatograms and results . 23
Annex B (informative) Operating parameters for other suitable detectors . 30
Bibliography . 31

–1
Figure A.1 – GC-ECD chromatogram of 2 mg kg DBDS and DPDS (IS) in white
mineral oil . 23
–1
Figure A.2 – GC-ECD chromatogram of 200 mg kg DBDS and DPDS (IS) in white
mineral oil . 24
Figure A.3 – GC-ECD chromatogram of commercial mineral insulating oil with a known
DBDS contamination . 24
Figure A.4 – GC-ECD chromatogram of commercial mineral insulating oil with no
known DBDS contamination . 25
Figure A.5 – GC-ECD chromatogram of commercial mineral insulating oil with known
DBDS contamination fortified with acommercial polychlorinated biphenyls (PCBs)
formulation. 25
Figure A.6 – Carbon and sulfur (C-S) oil finger prints of a commercial mineral
insulating oil with known DBDS contamination obtained with GC-AED . 26
Figure A.7 – C-S oil fingerprints of a commercial mineral insulating oil with no known
DBDS contamination obtained with GC-AED . 26
Figure A.8 – C-S oil fingerprints of a commercial mineral insulating oil with known
DBDS contamination obtained with GC-AED . 27
Figure A.9 – Extracted ion chromatograms of DPDS (IS) molecular ion m/z 218 and
DBDS molecular ion m/z 246 in white mineral fortified with DBDS, concentration
–1
4 mg kg . 27
Figure A.10 – Extracted ion chromatograms DPDS (IS) molecular ion m/z 218 and
DBDS molecular ion m/z 246 in commercial mineral insulating oil with known DBDS
contamination . 28
Figure A.11 – Extracted ion chromatograms m/z 109 derived from CID of DPDS (IS)
molecular ion m/z 218 and m/z 91 derived from CID of DBDS molecular ion m/z 246 in
white mineral fortified with DBDS (4 mg/kg) . 28

– 4 – 62697-1 © IEC:2012
Figure A.12 – Extracted ion chromatograms m/z 109 derived from CID of DPDS (IS)
molecular ion m/z 218 and m/z 91 derived from CID of DBDS molecular ion m/z 246 in
a commercial mineral oil with known DBDS contamination . 29

Table 1 – Column oven temperature programming parameters . 18
Table 2 – Mass spectrometer parameters . 18
Table 3 – Repeatability limit . 22
Table 4 – Reproducibility limit . 22

62697-1 © IEC:2012 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST METHODS FOR QUANTITATIVE DETERMINATION
OF CORROSIVE SULFUR COMPOUNDS IN UNUSED
AND USED INSULATING LIQUIDS –
Part 1: Test method for quantitative determination
of dibenzyldisulfide (DBDS)
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62697-1 has been prepared by IEC technical committee 10: Fluids
for electrotechnical applications.
The text of this standard is based on the following documents:
FDIS Report on voting
10/887/FDIS 10/891/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 6 – 62697-1 © IEC:2012
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
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IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
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62697-1 © IEC:2012 – 7 –
INTRODUCTION
Sulfur can be present in insulating liquids in various forms, including elemental sulfur,
inorganic sulfur compounds and organic sulfur compounds. The number of diverse sulfur
species comprised of different isomers and homologous can run into hundreds. The total
sulfur(TS) concentration in insulating liquids depends on the origin of the liquid, refining
processes and the degree of refining and formulation including addition of additives to the
base oils. Base oils include mineral based paraffinic and naphthenic oils, synthetic iso-
paraffins obtained through gas to liquid conversion process (GTL-Fischer-Tropsch), esters,
poly alpha olefins, poly alkylene glycols, etc. Additives can be comprised of electrostatic
discharge depressants, metal deactivators, metal passivators, phenolic and sulfur containing
antioxidants such as the polysulfides, disulfides, dibenzyl disulfide (DBDS), etc.
Certain sulfur compounds present in the insulating liquids exhibit antioxidant and metal
deactivating properties without being corrosive, whereas other sulfur compounds have been
known to react with metal surfaces. Specifically, sulfur compounds such as mercaptans are
very corrosive to metallic components of electrical devices. Presence of these corrosive sulfur
species has been linked to failures of electrical equipment used in generation, transmission
and distribution of electrical energy for several decades. Therefore, the IEC standard for
mineral insulating oils states that corrosive sulfur compounds shall not be present in unused
and used insulating liquids (see IEC 60296) [5] .
Recently, the serious detrimental impact of corrosive sulfur has been linked to the presence of
a specific highly corrosive sulfur compound, DBDS. This compound has been found in certain
mineral insulating oils [1, 14, 15, 16]; presence of this compound has been shown to result in
copper sulfide formation on the surfaces of copper conductors under normal operating
conditions of transformers [2].
Current standard test methods for detection of corrosive sulfur (ASTM D1275, methods A and
B, and DIN 51353) and potentially corrosive sulfur in used and unused insulating oil
(IEC 62535) are empirical and qualitative. These methods rely on visual and subjective
perception of colour profiles. The methods do not yield quantitative results in regard to the
concentration of DBDS or other corrosive sulfur compounds present in insulating liquids.
Furthermore, methods for corrosive sulfur and potentially corrosive sulfur in insulating liquids
(ASTM D1275, method B and IEC 62535) are applicable only to mineral insulating oils that do
not contain a metal passivator additive, the methods otherwise can yield negative results even
when corrosive sulfur compounds are present in the insulating liquids – thus providing a false
negative test result. On the other hand, the test method when used with aged insulating oils
(e.g. those with relative high acidity), may give ambiguous results and lead to a false positive
test result. Further analysis of insulating liquids is stipulated, e.g. IEC 62535 specifies that if
there are any doubts in the interpretation of the results of inspection of paper, the composition
of precipitate should be analyzed by other methods (for example by SEM-EDX).
For this reason, IEC TC 10 WG 37 was set up to prepare test methods for the unambiguous
quantitative determination of corrosive sulfur compounds in unused and used insulating
liquids. Because of the complexity of such determinations, the test methods are divided into
three parts:
Part 1 – Test method for quantitative determination of dibenzyldisulfide (DBDS).
Part 2 – Test methods for quantitative determination of total corrosive sulfur (TCS).
Part 3 – Test methods for quantitative determination of total mercaptans and disulfides (TMD)
and other targeted corrosive sulfur species.
___________
Figures in square brackets refer to the bibliography.

– 8 – 62697-1 © IEC:2012
Health and safety
This part of IEC 62697 does not purport to address all the safety problems associated with its
use. It is the responsibility of the user of the standard to establish appropriate health and
safety practices and determine the applicability of regulatory limitations prior to use.
The insulating liquids which are the subject of this standard should be handled with due
regard to personal hygiene. Direct contact with eyes may cause slight irritation. In the case of
eye contact, irrigation with copious quantities of clean running water should be carried out
and medical advice sought.
Some of the tests specified in this standard involve the use of processes that could lead to a
hazardous situation. Attention is drawn to the relevant standard for guidance.
Environment
This standard involves mineral insulating oils, natural ester insulating liquids, chemicals and
used sample containers. The disposal of these items should be carried out in accordance with
current national legislation with regard to the impact on the environment. Every precaution
should be taken to prevent the release of chemicals used during the test into the environment.

62697-1 © IEC:2012 – 9 –
TEST METHODS FOR QUANTITATIVE DETERMINATION
OF CORROSIVE SULFUR COMPOUNDS IN UNUSED
AND USED INSULATING LIQUIDS –
Part 1: Test method for quantitative determination
of dibenzyldisulfide (DBDS)
1 Scope
This part of IEC 62697 specifies a test method for the quantitative determination of corrosive
sulfur compounds-dibenzyl disulfide (DBDS) in used and unused insulating liquids over a 5 –
–1
600 mg kg concentration range.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60475, Method of sampling liquid dielectrics
IEC 62535:2008, Insulating liquids – Test method for detection of potentially corrosive sulfur
in used and unused insulating oil
3 Terms, definitions and abbreviations
For the purposes of this document, the following terms, definitions and abbreviations apply.
3.1 Terms and definitions
3.1.1
accuracy
closeness of agreement between test result and the accepted reference value
3.1.2
additive
a suitable chemical substance that is deliberately added to insulating liquid in order to
improve certain characteristics
Note 1 to entry: Examples include antioxidants, pour-point depressants, electrostatic charging tendency
depressant such as benzotriazol (BTA) metal passivator or deactivators, antifoam agent, refining process improver,
etc.
3.1.3
atomic emission detector
AED
simultaneously monitors emissions of radiation resulting from atomic species excited in a
microwave-induced plasma and permits quantitative determination of selected heteroatoms in
compounds that elute from a GC column
Note 1 to entry: AED thus provides heteroatom profiles, i.e. “fingerprints” of complex samples such as insulating
liquids.
– 10 – 62697-1 © IEC:2012
3.1.4
contaminants
foreign substances or materials in an insulating liquid or gas which usually has a deleterious
effect on one or more properties
[SOURCE: IEC 60050-212:2010, 212-17-27, modified]
3.1.5
corrosion
disintegration of a metal due to chemical reactions with sulfur and other chemical species in
insulating liquids
3.1.6
corrosive sulfur
free sulfur and corrosive sulfur compounds detected by subjecting metals such as copper to
contact with an insulating liquid under standardized conditions
[SOURCE: IEC 60050-212:2010, 212-18-20]
3.1.7
dibenzyl disulfide
DBDS
aromatic disulfide containing two benzyl functionalities with a molecular formula C H S ,
14 14 2
nominal molecular mass of 246 and a melting point of 71 – 72 °C
3.1.8
diphenyl disulfide
DPDS
aromatic disulfide with two phenyl functionalities with a molecular formula C H S , nominal
12 10 2
°
molecular mass of 218 and a melting point of 61 °C – 62 C
3.1.9
electron capture detector
ECD
device used for quantification of compounds with high electron affinity such as polychlorinated
aromatics, nitroaromatics and aromatic disulfides present in gas chromatography effluent at
very low concentrations
Note 1 to entry: ECD can have a radioactive internal ionization source (e.g. Ni) or thermal electron produced
through photo-induced ionization (e.g. helium discharge – HD or photoionization – PID).
3.1.10
flame photometric detector
FPD
detector that uses the chemiluminescent reaction of sulfur-containing compounds in a cool
*
hydrogen/air flame that result in the formation of excited S species, which decays with broad
radiant out around 394 nm that is monitored with an interference filter and a photomultiplier
3.1.11
homologue
compound belonging to a series of compounds that differ in the number of repeating groups
3.1.12
internal standard
IS
substance which is similar in the chemical behaviour (chemical structure – polarity) and
analytical response to a certain target analyte
Note 1 to entry: A defined volume of the internal standard solution is added to both the sample and calibration
solutions such that they both contain an identical concentration.

62697-1 © IEC:2012 – 11 –
3.1.13
isomer
compounds that have the same molecular formula but different structural formula
3.1.14
gas chromatograph
device used for separating volatile and semi-volatile compounds in mixtures that can be
vaporized without decomposition through differential migration with a carrier gas through a
column
3.1.15
mass spectrometer
MS
instrument used for ionizing neutral chemical species and separating ions according to their
mass to charge ratio
Note 1 to entry: It permits determining concentrations of target compounds in complex mixtures such as insulating
liquids.
3.1.16
mercaptans (thiols) and disulfides
corrosive organic compounds that contain the functional group composed of a sulfur-hydrogen
bond (-SH); disulfides are corrosive compounds that contain a linked pair of sulfur atoms ( S-
S, disulfide bond)
3.1.17
precision
closeness of agreement between independent test results obtained under stipulated
conditions (repeatability conditions or reproducibility conditions)
3.1.18
potentially corrosive sulfur
organo-sulfur compounds present in transformer oils that may cause copper sulfide formation
Note 1 to entry: Some of these compounds may be initially corrosive, or become corrosive under certain operating
conditions.
[SOURCE: IEC 62535:2008, 3.1]
3.1.19
qualitative analysis
analysis that establishes the presence or the absence of a compound in a sample
3.1.20
quantitative analysis
analysis that establishes the amount or concentration of a compound in a sample
3.1.21
repeatability conditions
conditions where independent test results are obtained with the same method on identical test
items in the same laboratory
3.1.22
repeatability limits
r
value less than or equal to which the absolute difference between two test results obtained
under repeatability conditions may be expected to be with a probability of 95 %

– 12 – 62697-1 © IEC:2012
3.1.23
reproducibility conditions
conditions where independent test results are obtained with the same method on identical test
items in different laboratories with different operators using different equipment
3.1.24
reproducibility limits
R
value less than or equal to which the absolute difference between two test results obtained
under reproducible conditions may be expected to be with a probability of 95 %
3.1.25
sulfur chemiluminescence detector
SCD
detector that makes use of a dual plasma burner to combust sulfur-containing compounds to
yield sulfur monoxide (SO)
Note 1 to entry: A photomultiplier tube detects the light produced by the chemiluminescent reaction of SO with
ozone. This results in a linear and equimolar response to the sulfur compounds without interference from most
sample matrices.
3.1.26
tandem mass spectrometer
MS/MS
system that permits selection of specific precursor ion/s and dissociation of these ions to
produce characteristic fragment ion/s
Note 1 to entry: Monitoring of fragment ions permits matrix interference-free quantification of targeted compounds
in complex samples.
3.1.27
total corrosive sulfur
TCS
sum of all free and chemically bound sulfur in an insulating liquid that reacts with metals such
as copper under certain operating conditions
3.1.28
total sulfur
TS
sum of all free sulfur and chemically bound sulfur present in an insulating liquid
3.1.29
trueness
closeness of agreement between the average value obtained from large series of test results
and an accepted reference value
3.1.30
unused mineral insulating oil
mineral insulating oil as delivered by the supplier
Note 1 to entry: Such oil should not have been used in, nor been in contact with, electrical equipment not required
for manufacture, storage or transportation.
Note 2 to entry: The manufacturer and supplier of unused oil will have taken all reasonable precautions to ensure
that there is no contamination with polychlorinated biphenyls or terphenyls (PCBs, PCTs), used, reclaimed or
dechlorinated oil or other contaminants
[SOURCE: IEC 60296:2012, definition 3.9, modified]

62697-1 © IEC:2012 – 13 –
3.2 Abbreviations
Abbreviation Term
AED atomic emission detection
DBDS dibenzyl disulfide
DPDS diphenyl disulfide
ECD electron capture detector
EI electron ionization
FPD flame photometric detector
GC gas chromatography
IS internal standard
MS mass spectrometer
SCD sulfur chemiluninescence detector
MS/MS tandem mass spectrometer
TCS total corrosive sulfur
TS total sulfur
4 Sampling
Samples shall be taken, following the procedure given in IEC 60475. A representative portion
shall be taken after thorough mixing. The specific sampling technique can affect the accuracy
of this test method.
Precautions should be taken to prevent cross-contamination during sampling.
5 Procedure
5.1 Principle
The oil sample is diluted approximately 1:20 with a suitable solvent, fortified with a known
amount of an internal standard (IS) such as DPDS, and injected into the split/splitless injector
of a gas chromatograph equipped with a suitable detector including an electron capture
detector (ECD), an atomic emission detector (AED), a sulfur chemiluminescence detector
(SCD), a flame photometric detector (FPD), a mass spectrometer (MS) or a tandem mass
spectrometer (MS/MS).
Separation of oil constituents, DBDS (if present) and DPDS is achieved with a suitable column
such as a 30 m to 60 m × 0,25 mm (internal diameter) fused silica column with 5 %
polyphenylsiloxane and 95 % methylpolysiloxane or other suitable stationary phase and
helium or other suitable carrier gas. Separation is facilitated through temperature
programming over a suitable temperature range. DBDS is monitored with the detector and
quantified with the internal standard.
NOTE Other suitable detectors such as sulfur chemiluminisence detector or flame photometric detector can be
used. However, these detectors were not used during the Round Robin Tests.
5.2 Significance and use
This test method describes the determination of DBDS in insulating liquids for analysis.
DBDS is an aromatic organosulfur compound, which may be present in insulating liquids and
impart oxidation stability to the liquids. However, DBDS can react with copper and other metal
conductors in transformers, reactors and other similar devices to form copper and other metal

– 14 – 62697-1 © IEC:2012
sulfides. Therefore, this compound is classified as potentially corrosive sulfur (see
IEC 62535).
–1
DBDS has been found in insulating mineral oils at concentrations ranging between 5 mg kg
–1
and 600 mg kg , but it may be present at levels outside this range, in oils that have been
blended, or oils in which DBDS have been consumed through its reaction with the copper or
other metals.
This method can be used for detecting and quantifying DBDS content in used and unused
insulating liquids.
5.3 Interferences
5.3.1 Co-eluting compounds
Interferences experienced during quantitative determination of DBDS will vary with the
detector used for quantification of DBDS separated with the gas chromatographic column.
5.3.2 Electron capture detector (ECD)
An ECD is a very sensitive and selective detector that responds to volatile/semi-volatile
compounds with high electron affinity. It has gained wide acceptance and use due to its very
high sensitivity and selectivity for certain classes of compounds, including halogenated
hydrocarbons, organometallic compounds, nitriles, or nitro compounds and disulfides.
Presence of such compounds especially polychlorinated biphenyls (PCBs) in insulating liquids
can cause interference. In such cases an alternate detector should be used.
5.3.3 Atomic emission detector (AED)
An AED responds to volatile and semi-volatile compounds separated with a gas
chromatograph that contains carbon and selected heteroatoms, including sulfur, nitrogen,
oxygen and halogens (fluorine, chlorine, bromine and iodine). AED can thus provide a carbon
and heteroatom fingerprint of complex mixtures such as insulating liquids. It can be used for
quantification of selected additives and their homologues with minimum interferences. It can
also be used for determination of origin and formulation through pattern recognition.
Interferences can arise from co-eluting sulfur compounds.
5.3.4 Mass spectrometer (MS)
MS is a very sensitive and selective detector that responds to the volatile and semi-volatile
compounds. It has gained wide acceptance and use due to its very high sensitivity and
selectivity for a broad class of compounds. Compounds present in the GC effluent that give
yield ions at m/z 246 or m/z 218 will cause interference if such compounds elute from the GC
column with retention times similar to those of the DBDS and DPDS (IS).
5.3.5 MS/MS
MS/MS is a highly sensitive detector that can yield greater specificity for targeted volatile and
semi-volatile compounds separated with a gas chromatograph. It minimizes background
interferences arising from complex matrices and enhances certainty in quantitative
determination of DBDS, other compounds, their isomers (compounds with the same elemental
composition but different connectivity) and their homologues (compounds with the same
functional group(s) but a different carbon chain) in insulating liquids. This detector provides a
largely interference-free response.
5.3.6 Interference from the matrix
The insulating liquid matrix is comprised of hydrocarbons that do not respond well in the ECD;
therefore, matrix interference should be low with GC-ECD.

62697-1 © IEC:2012 – 15 –
AED response is selective for heteratoms present in an organic compound; therefore, matrix
interference should not be encountered.
It is possible that certain insulating liquids can contain molecules that yield ions at m/z 246
and m/z 218. Such molecules can cause interferences with GC-MS.
MS/MS response is highly specific for target compound; therefore, matrix interference should
not be present.
5.4 Apparatus
5.4.1 Balance
A balance with a capability for automatic tare, accuracy down to 0,001 g, and a maximum
weight range of ≥ 100 g is required.
5.4.2 Gas chromatography system
5.4.2.1 General
Gas chromatograph equipped with:
– a split/splitless injector with temperature stability of better than 0,5 °C and maximum
operating temperature above 300 °C;
– an injection device suitable for introducing 1 μl – 10 μl liquids into the column (an
automated sampling injection device is preferred);
– a 30 m à 60 m × 0,25 mm (internal diameter) fused silica capillary column with 5 % phenyl
polysiloxane and 95 % methylpolysiloxane or other suitable stationary phase;
– a column oven capable of operation over the 30 °C – 300 °C range with ramp rates of up
-1
to 20 °C min .
5.4.2.2 ECD
ECD with a Ni foil detector capable of operating at temperature ~ 300 °C with temperature
stability of ≤ 0,5 °C.
5.4.2.3 Atomic emission detector(AED)
AED capable of detecting the sulfur emission line at 181 nm (or other suitable sulfur emission
line).
5.4.2.4 Mass spectrometer (MS)
– quadrupole or other suitable MS with an electron ionization (EI) source, operated in
positive ion selected ion monitoring (SIM) mode;
– electron energy 70 eV;
– GC – MS interface temperature 270 °C with temperature stability of ≤ 0,5 °C;
– source temperature 200 °C or as recommended by the manufacturer.
5.4.2.5 MS/MS
– triple quadrupole or other suitable MS with an (EI) source, operated in positive ion SIM
mode;
– electron energy 70 eV;
– GC – MS interface temperature 270 °C with temperature stability of ≤ 0,5 °C;
– source temperature 200 °C or as recommended by the manufacturer;

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– system shall permit selection of precursor ions, dissociation of precursor ion into
characteristic fragment ions and quantification of the fragment ions.
5.4.3 Data system
For control, monitoring, acquisition and storage of analytical data.
5.5 Reagents and materials
5.5.1 Purity of reagents
Analytical reagent grade chemicals shall be used in all analysis performed with this method.
5.5.2 Gases
The carrier gas (He or other suitable gases) shall have purity equal to or better than 99,999 %
(grade 5). Refer to the specifications provided by the manufacturer of the GC system to verify
the purity requirements.
Make up gas for the ECD shall be nitroge
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