ISO 13914:2013

Soil quality - Determination of dioxins and furans and dioxin-like polychlorinated biphenyls by gas chromatography with high-resolution mass selective detection (GC/HRMS)

ISO 13914:2013 specifies a method for quantitative determination of 17 2,3,7,8-chlorine substituted dibenzo-p-dioxins and dibenzofurans and dioxin-like polychlorinated biphenyls in sludge, treated biowaste, and soil using liquid column chromatographic clean-up methods and GC/HRMS.

Qualité du sol — Détermination des dioxines et furanes comme biphényls polychlorés par chromatographie en phase gazeuse avec spectrométrie de masse à haute résolution (CG/SMHR)

General Information

• Status: Withdrawn
• Publication Date: 19-Nov-2013
• ICS: 13.080.10 - Chemical characteristics of soils
• Technical Committee: ISO/TC 190/SC 3 - Chemical and physical characterization
• Drafting Committee: ISO/TC 190/SC 3/WG 6 - Organic analysis
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 22-Feb-2023
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 13914:2023 - Soil, treated biowaste and sludge - Determination of dioxins and furans and dioxin-like polychlorinated biphenyls by gas chromatography with high resolution mass selective detection (HR GC-MS)
• Effective Date: 21-Aug-2021

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13914
First edition
2013-12-01
Soil quality — Determination of
dioxins and furans and dioxin-like
polychlorinated biphenyls by gas
chromatography with high-resolution
mass selective detection (GC/HRMS)
Qualité du sol — Détermination des dioxines et furanes comme
biphényls polychlorés par chromatographie en phase gazeuse avec
spectrométrie de masse à haute résolution (CG/SMHR)
Reference number
©
ISO 2013
© ISO 2013
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ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Abbreviated terms . 2
4 Principle . 2
5 Reagents . 3
5.1 Chemicals . 3
5.2 Standards . 3
6 Apparatus and materials. 3
6.1 General . 3
6.2 Equipment for sample preparation . 3
6.3 Soxhlet extractor . 3
6.4 Clean-up apparatus . 4
6.5 Concentration apparatus . 4
6.6 Other equipment . 4
7 Sample storage and sample pretreatment . 5
7.1 Sample storage . 5
7.2 Sample pretreatment . 5
8 Extraction and clean-up . 5
8.1 General . 5
8.2 Extraction . 6
8.3 Clean-up . 6
8.4 Final concentration of cleaned sample extract. 7
8.5 Addition of recovery standard . 8
9 GC/HRMS analysis . 8
9.1 General . 8
9.2 Gas chromatographic analysis . 8
9.3 Mass spectrometric detection . 8
9.4 Minimum requirements for identification of PCDF/PCDD and PCB . .10
9.5 Minimum requirements for quantification of PCDF/PCDD and PCB .10
9.6 Calibration of the GC/HRMS system .11
9.7 Quantification of GC/HRMS results .13
10 Precision .15
11 Test report .15
Annex A (informative) Toxic equivalent factors.16
Annex B (informative) Repeatability and reproducibility data .18
Annex C (informative) Examples of extraction and clean-up methods .21
Annex D (informative) Examples of operation of GC/HRMS determination .29
Bibliography .33
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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical
methods and soil characteristics.
iv © ISO 2013 – All rights reserved

Introduction
Two groups of related chlorinated aromatic ethers are known as polychlorinated dibenzo-p-
dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). They consist of a total of 210 individual
substances (congeners): 75 PCDDs and 135 PCDFs.
A group of chlorinated aromatic compounds similar to polychlorinated dibenzo-p-dioxins (PCDDs) and
polychlorinated dibenzofurans (PCDFs) is known as polychlorinated biphenyls (PCBs) which consist of
209 individual substances.
PCDDs and PCDFs can form in the combustion of organic materials. They also occur as undesirable by-
products in the manufacture or further processing of chlorinated organic chemicals. PCDDs/PCDFs
enter the environment via these emission paths and through the use of contaminated materials.
In fact, they are universally present at very small concentrations. The 2,3,7,8-substituted congeners
are toxicologically significant. Toxicologically much less significant than the tetrachlorinated to
octachlorinated dibenzo-p-dioxins/dibenzofurans are the 74 monochlorinated to trichlorinated
dibenzo-p-dioxins/dibenzofurans.
PCBs have been produced over a period of approximately 50 y until the end of the 1990s for the purpose
of different uses in open and closed systems, e.g. as electrical insulators or dielectric fluids in capacitors
and transformers, as specialized hydraulic fluids, or as a plasticizer in sealing material. Worldwide,
more than 1 million tons of PCBs were produced.
PCDD/Fs as well as PCBs are emitted during thermal processes such as waste incineration. In 1997, a group
of experts of the World Health Organization (WHO) fixed toxicity equivalent factors (TEF) for PCDDs and
12 PCBs, known as dioxin-like PCBs (see Annex A). These 12 dioxin-like PCBs consist of four non-ortho
PCBs and eight mono-ortho PCBs (no or only one chlorine atoms in 2-, 2’-, 6- and 6’-position), having a
planar or mostly planar structure. Dioxin-like PCBs can contribute considerably to the total WHO-TEQ.
Only skilled operators who are trained in handling highly toxic compounds should apply the method
described in this International Standard.
This International Standard is applicable for several types of matrices and validated for municipal sludge
(see Annex B for the results of the validation).
INTERNATIONAL STANDARD ISO 13914:2013(E)
Soil quality — Determination of dioxins and furans
and dioxin-like polychlorinated biphenyls by gas
chromatography with high-resolution mass selective
detection (GC/HRMS)
WARNING — Persons using this International Standard should be familiar with usual laboratory
practice. This International Standard 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 ensure compliance with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted according to this International
Standard be carried out by suitably trained staff.
1 Scope
This International Standard specifies a method for quantitative determination of 17 2,3,7,8-chlorine
substituted dibenzo-p-dioxins and dibenzofurans and dioxin-like polychlorinated biphenyls in sludge,
treated biowaste, and soil using liquid column chromatographic clean-up methods and GC/HRMS.
The analytes to be determined with this International Standard are listed in Table 1.
Table 1 — Analytes and their abbreviations
Substance Abbreviation
Tetrachlorodibenzo-p-dioxin TCDD
Pentachlorodibenzo-p-dioxin PeCDD
Hexachlorodibenzo-p-dioxin HxCDD
Heptachlorodibenzo-p-dioxin HpCDD
Octachlorodibenzo-p-dioxin OCDD
Tetrachlorodibenzofuran TCDF
Pentachlorodibenzofuran PeCDF
Hexachlorodibenzofuran HxCDF
Heptachlorodibenzofuran HpCDF
Octachlorodibenzofuran OCDF
Polychlorinated biphenyl PCB
Trichlorobiphenyl TCB
Tetrachlorobiphenyl TeCB
Pentachlorobiphenyl PeCB
Hexachlorobiphenyl HxCB
Heptachlorobiphenyl HpCB
Decachlorobiphenyl DecaCB
The limit of detection depends on the kind of sample, the congener, the equipment used, and the quality
of chemicals used for extraction and clean-up. Under the conditions specified in this International
Standard, limits of detection better than 1 ng/kg (expressed as dry matter) can be achieved.
This method is “performance based”. It is permitted to modify the method if all performance criteria
given in this method are met.
NOTE In principle, this method can also be applied for sediments, mineral wastes, and for vegetation. It is
the responsibility of the user of this International Standard to validate the application for these matrices. For
measurement in complex matrices like fly ashes adsorbed on vegetation, it can be necessary to further improve
the clean-up. This can also apply to sediments and mineral wastes.
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.
ISO 14507, Soil quality — Pretreatment of samples for determination of organic contaminants
3 Abbreviated terms
PCB polychlorinated biphenyls
PCDD/PCDF or PCDD/F polychlorinated dibenzo-p-dioxins/dibenzofurans
I-TEF NATO/CCMS international toxic equivalent factor, proposed by NATO-CCMS in 1988 (for a
detailed description, see Annex A)
I-TEQ international toxic equivalent, obtained by multiplying the mass determined
with the corresponding I-TEF including PCDDs and PCDFs (for a detailed
description, see Annex A). Should only be used for comparison with older
data
WHO-TEF toxic equivalent factor, proposed by WHO in 2005 (for detailed description,
see Annex A)
WHO-TEQ toxic equivalent, obtained by multiplying the mass determined with the
corresponding WHO-TEF including PCDD, PCDF, and PCB (for detailed
description, see Annex A). WHO-TEQ , WHO-TEQ should be used to
PCB PCDD/F
distinguish different compound classes
4 Principle
This International Standard is based on the use of gas chromatography/mass spectrometry combined
with the isotope dilution technique to enable the separation, detection, and quantification of PCDD/PCDF
and dioxin-like PCB in sludge, biowaste, and soil. For the isotope dilution method, 17 labelled PCDD/F
and 12 labelled PCB internal standards are used. The extracts for the GC-MS measurements contain
one or two recovery standards. The gas chromatographic parameters offer information which enables
the identification of congeners (position of chlorine substitutes) whereas the mass spectrometric
parameters enable the differentiation between isomers with different numbers of chlorine substitutes
and between dibenzo-p-dioxins, furans, and PCBs.
C -labelled PCDD/F and PCB congeners are added to the sample prior to extraction and GC/HRMS
measurement. Losses during extraction and clean-up are detected and compensated by using these
added congeners as internal standards for quantification together with recovery standards which are
added just before the GC/HRMS analysis. For the determination of these substances, it is necessary to
separate PCBs from PCDDs/PCDFs and vice versa.
The main purpose of the clean-up procedure of the raw sample extract is the removal of sample matrix
components, which can overload the separation method, disturb the quantification, or otherwise
2 © ISO 2013 – All rights reserved

severely impact the performance of the identification and quantification method and the separation of
PCDD/F from dioxin-like PCB. Furthermore, the enrichment of the analytes in the final sample extract
is achieved. Extraction procedures are usually based on Soxhlet or equivalent extraction methods of
dried, preferably freeze-dried, samples. Sample clean-up is usually carried out by multi-column liquid
chromatographic techniques using different adsorbents. The determination of PCDD/Fs and PCBs is
based on quantification by the isotope dilution technique using GC/HRMS.
5 Reagents
5.1 Chemicals
Solvents used for extraction and clean-up shall be of pesticide grade or equivalent quality and checked
for blanks. Adsorbents like aluminium oxide, silica gel, diatomaceous earth, and others used for clean-up
shall be of analytical grade quality or better and pre-cleaned and activated if necessary.
NOTE See Annex C for a specific list of solvents and chemicals.
5.2 Standards
— C -spiking solution for PCDD/F (internal standard);
— C -spiking solution for PCB (internal standard);
— calibration solutions PCDD/F;
— calibration solutions PCB;
— recovery standard PCDD/F;
— recovery standard PCB.
NOTE See Annex C for examples of concentration of the standard solutions.
6 Apparatus and materials
6.1 General
The apparatus and materials listed below are meant as minimum requirements for “conventional”
sample treatment with Soxhlet extraction and column chromatographic clean-up. Additional apparatus
and materials may be necessary due to different methods of sample extraction and clean-up methods.
6.2 Equipment for sample preparation
6.2.1 Laboratory fume hood, of sufficient size to contain the sample preparation equipment listed below.
6.2.2 Desiccator.
6.2.3 Balances, consisting of an analytical type capable of weighing 0,1 mg and a top-loading type
capable of weighing 10 mg.
6.3 Soxhlet extractor
6.3.1 Soxhlet, 50 mm internal diameter, 150 ml or 250 ml capacity with 500 ml round bottom flask.
6.3.2 Thimble, 43 mm × 123 mm, to fit Soxhlet.
6.3.3 Hemispherical heating mantle, to fit 500 ml round-bottom flask.
6.4 Clean-up apparatus
6.4.1 Disposable pipettes, either disposable Pasteur pipettes, or disposable serological pipettes.
6.4.2 Glass chromatographic columns, of the following sizes:
— 150 mm length × 8 mm internal diameter, with coarse-glass frit or glass-wool plug, 250 ml reservoir,
and glass or polytetrafluoroethylene (PTFE) stopcock;
— 200 mm length × 15 mm internal diameter, with coarse-glass frit or glass-wool plug, 250 ml reservoir,
and glass or PTFE stopcock;
— 300 mm length × 25 mm internal diameter, with coarse-glass frit or glass-wool plug, 300 ml
reservoir, and glass or PTFE stopcock.
6.4.3 Oven, capable of maintaining a constant temperature (±5 °C) in the range of 105 °C to 450 °C for
baking and storage of adsorbents.
6.5 Concentration apparatus
6.5.1 Rotary evaporator, equipped with a variable temperature water bath and:
— a vacuum source for the rotary evaporator equipped with a shutoff valve at the evaporator and
vacuum gauge;
— a recirculating water pump and chiller, providing cooling water of (9 ± 4) °C (use of tap water for
cooling the evaporator wastes large volumes of water and can lead to inconsistent performance as
water temperatures and pressures vary);
— round-bottom flask, 100 ml and 500 ml or larger, with ground-glass fitting compatible with the
rotary evaporator.
6.5.2 Nitrogen blowdown apparatus, equipped with either a water bath controlled in the range of
30 °C to 60 °C or a heated stream of nitrogen, installed in a fume hood.
1)
6.5.3 Kuderna-Danish concentrator.
6.5.4 Sample vials, of the following types:
— amber glass, nominated volume 2 ml to 5 ml, with PTFE-lined screw cap;
— glass, 0,3 ml, conical, with PTFE-lined screw or crimp cap.
6.6 Other equipment
6.6.1 Gas chromatograph, equipped with a splitless or on-column or temperature-programmed
injection port for use with capillary columns, and an oven temperature programme which enables
isothermal hold.
1) Kuderna Danish is an example of a suitable product available commercially. This information is given for the
convenience of users of this International Standard and does not constitute an endorsement by ISO of this product.
4 © ISO 2013 – All rights reserved

6.6.2 GC column for PCDDs/PCDFs and for isomer specificity for 2,3,7,8-TCDD (e.g. 60 m
length × 0,32 mm internal diameter; 0,25 µm; 5 % phenyl, 94 % methyl, 1 % vinyl silicone bonded-phase
fused-silica capillary column).
6.6.3 Mass spectrometer, 28 eV to 80 eV electron impact ionization, capable of repetitively selectively
monitoring 12 exact masses minimum at high resolution (>10 000) during a period of approximately 1 s.
6.6.4 Data system, capable of collecting, recording, and storing mass spectrometric data.
7 Sample storage and sample pretreatment
7.1 Sample storage
Samples should be stored in suitable containers with an appropriate closure material such as
polytetrafluoroethylene (PTFE). Samples to be frozen can be stored in aluminium containers pre-
cleaned by heating to 450 °C for a minimum of 4 h or by rinsing with a non-chlorinated solvent.
Samples should be kept cold (<8 °C) and in the dark. The sample pretreatment should take place within
3 d of sampling. Alternatively, samples can be frozen (–18 °C) directly after sampling and kept frozen
before sample pretreatment.
7.2 Sample pretreatment
Drying and homogenization should be carried out according to ISO 14507, if not otherwise specified.
Store the ground material in a desiccator or a tightly closed glass container.
8 Extraction and clean-up
8.1 General
In this International Standard, the minimum requirements for extraction and clean-up to be met are
described as well as examples of operation. The analyst can use any of the procedures given below and
in Annex C or any suitable alternative procedures.
The determination of PCDDs/PCDFs is based on quantification by the isotope dilution technique using
GC/HRMS. C -labelled 2,3,7,8-chlorine substituted PCDD/PCDFs congeners are added at different
stages of the whole method. Losses during extraction and clean-up can be detected and compensated by
using these added congeners as internal standards for quantification together with recovery standards
which are added just before the GC/HRMS analysis. However, due to possible differences in the binding
and adsorption characteristics between the native PCDDs/PCDFs and the C -labelled congeners,
which are added during analysis, complete substantiation of the extraction efficiency and compensation
of losses during clean-up is not ensured. Therefore, in addition, the applied methods shall be validated
thoroughly. Examples of well-proven extraction and clean-up methods are given in Annex C.
The main purpose of the clean-up procedure of the raw sample extract is the removal of sample matrix
components, which can overload the separation method, disturb the quantification, or otherwise
severely impact the performance of the identification and quantification method and to separate
dioxin-like PCB from PCDD/F. Furthermore, an enrichment of the analytes in the final sample extract is
achieved. Extraction procedures are usually based on Soxhlet extraction of the <2 mm fraction of the
dry and ground or sieved solid sample. Sample clean-up is usually carried out by multi-column liquid
chromatographic techniques using different adsorbents.
In principle, any clean-up method can be used which recovers the analytes in sufficient quantities.
Furthermore, the final sample extract shall not affect adversely the performance of the analytical system
or the quantification step. However, all applied methods shall be tested thoroughly and shall pass a
set of method validation requirements before they can be employed. In addition, the verification of the
method performance for each single sample shall be part of the applied quality assurance protocol.
8.2 Extraction
The sample amount used for extraction can vary from 5 g to 50 g depending on the expected level of
contamination.
The internal standard consisting of C -labelled congeners listed in Table 2 shall be added directly
into the sample before extraction.
The extraction procedure is carried out using Soxhlet extraction with toluene. The duration of extraction
should be adjusted according to the kind and amount of sample used. The minimum requirement is
50 extraction cycles or approximately 12 h.
Other solvents or other methods like pressurized liquid extraction can also be used but shall be of
proven equal performance.
Table 2 — C -labelled congeners included in the internal standard
C -spiking solution — internal standard
PCDD/F congeners PCB congeners
13 13
2,3,7,8- C -TCDD C -PCB-77
12 12
13 13
1,2,3,7,8- C -PeCDD C -PCB-81
12 12
13 13
1,2,3,4,7,8- C -HxCDD C -PCB-126
12 12
13 13
1,2,3,6,7,8- C -HxCDD C -PCB-169
12 12
1,2,3,7,8,9- C -HxCDD
13 13
1,2,3,4,6,7,8- C -HpCDD C -PCB-105
12 12
13 13
C -OCDD C -PCB-114
12 12
C -PCB-118
13 13
2,3,7,8- C -TCDF C -PCB-123
12 12
13 13
1,2,3,7,8- C -PeCDF C -PCB-156
12 12
13 13
2,3,4,7,8- C -PeCDF C -PCB-157
12 12
13 13
1,2,3,4,7,8- C -HxCDF C -PCB-167
12 12
13 13
1,2,3,6,7,8- C -HxCDF C -PCB-189
12 12
2,3,4,6,7,8- C -HxCDF
1,2,3,7,8,9- C -HxCDF
1,2,3,4,6,7,8- C -HpCDF
1,2,3,4,7,8,9- C -HpCDF
C -OCDF
8.3 Clean-up
8.3.1 General
Clean-up methods shall prepare the sample extract in an appropriate manner for the subsequent
quantitative determination. Clean-up procedures shall concentrate PCDD/Fs and dioxin-like PCBs in the
extracts and remove interfering matrix components present in the raw extract.
Proven clean-up procedures shall be used including usually two or more of the following techniques which
can be combined in different orders. A detailed description of some of the procedures is given in Annex C.
6 © ISO 2013 – All rights reserved

Other methods can also be used but shall be of proven equal performance as the techniques described below.
8.3.2 Gel permeation chromatography
The interesting molecular weight range for PCDD/Fs and dioxin-like PCBs of 200 g/mol to 500 g/mol
can be isolated from larger molecules and polymers which might overload other clean-up methods. This
method can also be used for the removal of sulfur.
8.3.3 Multilayer column
Multilayer column liquid chromatography using silica with different activity grades and surface modifications.
Compounds with different chemical properties than PCDD/Fs and dioxin-like PCBs can be removed.
8.3.4 Sulfuric acid treatment
A direct treatment of the sample extract with sulfuric acid is possible but is not recommended due to
risk of accident. If applied, this shall be carried out very carefully to avoid losses of PCDD/Fs and dioxin-
like PCBs on the formed carboniferous surfaces.
8.3.5 Activated carbon column
Column adsorption chromatography using activated carbon can be used to separate planar PCDD/F and
coplanar PCB molecules from mono-ortho PCB and other interfering non-planar molecules.
8.3.6 Aluminium oxide column
Column liquid chromatography on aluminium oxide of different activity grade and acidity/basicity.
Interfering compounds with small differences in polarity or structure compared to PCDD/Fs and dioxin-
like PCBs can be removed.
Additionally, aluminium oxide columns can be used to separate PCDD/Fs from dioxin-like PCBs.
8.3.7 Removal of sulfur
The removal of sulfur can be achieved by refluxing the extract with powdered copper or by gel permeation
chromatography.
8.4 Final concentration of cleaned sample extract
To achieve sufficient detection limits, the cleaned sample extract shall be concentrated to a volume in
the order of 25 µl to 100 µl before quantification. The final solvent shall be nonane, toluene, or another
solvent with a high boiling point.
Though PCDD/Fs have rather high boiling points (>320 °C), vapour phase transfer mechanisms and
aerosol formation during solvent evaporation might lead to substantial losses when concentrating
volumes below 10 ml. Depending on the method to be used for solvent volume reduction, the following
precautions shall be taken into consideration:
a) Rotary evaporators
Losses might be substantial when reducing solvent volumes below 10 ml. Counter measures include the
use of controlled vacuum conditions according to the vapour pressure and boiling point of the solvent,
addition of a high-boiling solvent as a keeper, as well as the use of specially shaped vessels (e.g. V-shaped).
b) Counter gas flow evaporators
Volumes should not be reduced to less than 1 ml.
c) Nitrogen flow
An excessive flow of nitrogen which disturbs the solvent surface should be avoided. The vial shape has
also some influence on possible losses. V-shaped vials or vial inserts shall be used for volume reductions
below around 200 µl.
d) Kuderna Danish
To avoid initial losses, prewet the column with about 1 ml of solvent. Boiling chips should be added and
the vertical position of the apparatus should be adjusted. At the proper rate of distillation, the balls of
the column will actively chatter but the chambers will not flood. Adjust the water bath temperature
accordingly. When reaching an extract volume of 1 ml, remove the evaporation flask, replace the snyder
column with a smaller one, and continue the evaporation.
8.5 Addition of recovery standard
The very last step before quantification is the addition of the recovery standards for calculation of the
recovery rates of the internal standards.
Recovery standards shall be added just prior to the quantification procedure. Samples with the recovery
standard added which could not be analysed due to operational reasons (instrument failure) should be
stored as briefly as possible and any further uncontrolled solvent evaporation shall be avoided.
Recovery standards shall be added after the final volume reduction. Any further direct volume reduction
shall be avoided. A slow evaporation at room temperature from the open sample vial to a volume of
about 25 µl is acceptable.
9 GC/HRMS analysis
9.1 General
GC-MS analyses of PCDD/Fs and dioxin-like PCBs shall be carried out on a high-resolution GC-MS
instrument equipped with a high-resolution gas chromatograph, an autosampler, a high-resolution mass
spectrometer, and a data system for instrument control, data acquisition, and processing.
9.2 Gas chromatographic analysis
Gas chromatographic separation shall be carried out in such a way that sufficient separation of all PCDD/F
and dioxin-like PCB congeners is achieved and the quality criteria specified in 9.4 and 9.5 are met.
For PCDD/F, there is no capillary column available at present that allows the separation of all
2,3,7,8-substituted congeners from all other non-2,3,7,8-substituted congeners. Complete separation
can only be achieved by analysing a sample on different capillary columns of different polarity.
For dioxin-like PCB analysis, similar problems exist for the separation of all coplanar and mono-ortho
congeners. There is no column available at present which is able to separate all 12 dioxin-like PCB
congeners from all other non-dioxin-like PCB congeners.
9.3 Mass spectrometric detection
A high-resolution mass spectrometer at a minimum resolution of 10 000 is used for the detection of
PCDD/F and dioxin-like PCB. This allows the use of C -labelled congeners as internal standards for
all 17 PCDD/F congeners and 12 dioxin-like PCB congeners of interest.
The mass spectrometer is used in the MID mode (multiple ion detection). The GC column is directly
coupled to the mass spectrometer. The ion source temperature should be between 250 °C to 270 °C
depending on the type of instrument. To achieve appropriate sensitivity, the detection capability should
be at least 200 fg for 2,3,7,8-TCDD.
8 © ISO 2013 – All rights reserved

For identification and quantification, the masses given in Table 3 and Table 4 shall be recorded in MID
mode. For each PCDD/F or PCB congener of interest, at least two ions of the molecular isotope cluster
shall be recorded for both the native and the added C -labelled congeners.
In addition, masses for quality control of the mass calibration shall be measured depending on the type
of instrument, e.g. lock mass, calibration mass, lock mass check.
The time slots for the MID windows shall be defined by a calibration standard in a way that all congeners
of interest elute within the related MID window. In case the sum of the concentrations of isomer groups
are needed, the retention time window for all isomers of an isomer group shall be defined by measuring
a standard mixture containing the first and last eluting isomers of each isomer group corresponding
to the used GC column. As an alternative, a fly ash extract or any other solution containing all native
PCDD/F congeners can be used.
Table 3 — Masses for the detection and quantification of PCDD/F
Dibenzofurans Dibenzo-p-dioxins
Substance
12 13 12 13
C C C C
303,901 6 315,941 9 319,896 5 331,936 8
Tetra-CDD/F
305,898 7 317,938 9 321,893 7 333,933 9
339,859 8 351,900 0 355,854 7 367,894 9
Penta-CDD/F
341,856 9 353,897 0 357,851 8 369,891 9
373,820 8 385,861 0 389,815 7 401,855 9
Hexa-CDD/F
375,817 9 387,858 0 391,812 8 403,852 9
407,781 8 419,822 0 423,776 7 435,816 9
Hepta-CDD/F
409,778 9 421,819 0 425,773 8 437,814 0
441,742 8 453,783 0 457,737 7 469,777 9
Octa-CDD/F
443,739 9 455,780 1 459,734 8 471,775 0
Table 4 — Masses for the detection and quantification of PCB
12 13
Homologue groups C C
255,961 3 268,001 6
Trichloro-PCB
257,958 4 269,998 6
289,922 3 301,962 6
Tetrachloro-PCB
291,919 4 303,959 7
325,880 4 337,920 7
Pentachloro-PCB
327,877 5 339,917 7
359,841 5 371,881 7
Hexachloro-PCB
361,838 5 373,878 8
393,802 5 405,842 7
Heptachloro-PCB
395,799 5 407,839 8
427,763 5 439,803 8
Octachloro-PCB
429,760 6 441,800 8
461,724 5 473,764 8
Nonachloro-PCB
463,721 6 475,761 8
497,682 6 509,722 9
Decachloro-PCB
499,679 7 511,719 9
9.4  Minimum requirements for identification of PCDF/PCDD and PCB
9.4.1 The isotope ratio between the two ions of the molecular isotope cluster which are recorded shall
match the theoretical value within ±15 % (see Table 5).
Table 5 — Limits of isotope ratios
Isotope ratio Isotope ratio theoreti- Isotope ratio
Substance
lower limit cal value upper limit
TCDD/F 0,65 0,77 (M/M+2) 0,88
PeCDD/F 0,55 0,64 (M+4/M+2) 0,75
HxCDD/F 0,69 0,81 (M+4/M+2) 0,94
HpCDD/F 0,83 0,96 (M+4/M+2) 1,13
OCDD/F 0,74 0,89 (M+2/M+4) 1,009
9.4.2 The retention time of a native 2,3,7,8-chlorine substituted isomer (Cl - to Cl -congeners) shall
4 6
be within a time window of +3 s to –3 s based on the retention time of the corresponding C -labelled
isomer in the sample. For the identification of low concentrations (S/N < 10), a time window of ±10 s is
acceptable. Alternatively, relative retention times based on the recovery standard (e.g. C -1,2,3,4-TCDF)
can be calculated. The difference shall not be more than 0,3 % compared with the calibration standard.
9.4.3 The signal-to-noise ratio of the raw data shall be at least 3:1 for three consecutive scans for the
signal used for identification. The base line noise shall be measured in front of the signal of the native
congener within a signal-free window corresponding to 10 times the signal width at half height. Peak-to-
peak values are taken.
9.5  Minimum requirements for quantification of PCDF/PCDD and PCB
9.5.1 For PCDD/F analysis, there is no chromatographic column available at present that is able to
separate all 2,3,7,8-chlorine substituted congeners from all other non-2,3,7,8-chlorine substituted
congeners. Complete separation can only be achieved by multi-analysis of the sample on different columns
of different natures (polarity).
Single column data can therefore be reported by this method. However, in cases where a regulatory
limit is exceeded or congener-specific data are needed, a confirmatory analysis should be performed on
a second column.
For dioxin-like PCB analysis, similar problems exist for the separation of all coplanar and mono-ortho
congeners. There is no column available at present which is able to separate all 12 dioxin-like PCB
congeners from all other non-dioxin-like PCB congeners. The use of one relatively non-polar column
(e.g. DB-5) is the common technique. The separation of congener PCB-123 is the crucial point of the
gas chromatographic separation. But due to the minor contribution to the overall TEQ, this leads to an
inessential increase of the uncertainty of the method.
9.5.2 The peak shape of the gas chromatographic signal of a congener shall contain 10 or more sampling
points (scanning units).
9.5.3 2,3,7,8-TCDD shall be separated from all other interfering isomers within a 25 % valley below the
top of the minor peak with respect to the height of that peak.
9.5.4 The recovery rate of each individual 2,3,7,8-chlorine substituted PCDD/PCDF of the internal
standards in each sample shall be within:
— 50 % to 130 % for the tetra- to hexa-chlorinated congeners or
10 © ISO 2013 – All rights reserved

— 40 % to 130 % for the hepta- and octachlorinated congeners.
NOTE If the above ranges are exceeded for one or more congeners, then the ranges given below are
acceptable for congeners with recoveries not within these ranges if the sum of the concentrations of those
congeners contribute less than 10 % to the total TEQ in the sample.
— 30 % to 150 % for the tetra- to hexa-chlorinated congeners or
— 20 % to 150 % for the hepta- and octa-chlorinated congeners.
9.5.5 The signal-to-noise ratio of the signal of the C -labelled congeners used for quantification
shall be >20:1.
9.5.6 The measuring range shall be linear (at least over a concentration range of a factor of 100). The
standard deviation of the relative response factor shall not exceed 15 % and shall be based on a minimum
of five measuring points over the whole range.
9.5.7 An analytical blank shall be analysed as defined in 9.6. The blank values of all congeners of interest
shall be equal or less than the detection limit of the method. Alternatively, the levels found shall be at least
a factor of 10 below the lowest measured concentrations in the series of samples.
9.6 Calibration of the GC/HRMS system
9.6.1 General
The calibration is carried out with at least five calibration solutions. These solutions contain all native
congeners of interest in different precisely defined amounts and all C -labelled standards (internal
and recovery standards) in the same concentrations as expected in the spiked sample solutions assuming
100 % recovery. The calibration range should encompass the concentrations of the sample.
9.6.2 Calibration for 2,3,7,8-congeners
The calibration curve is used to calculate the relative response factors for each congener of interest. The
relative response factors are used together with the C -labelled congeners added to the sample to
quantify the mass of the native congeners of interest by the isotope dilution method.
Calibration frequency depends on the stability of the instrument. Daily calibration checks shall be run.
In addition, a full calibration shall be repeated after major changes such as:
a) use of new or repaired equipment;
b) replacement of GC columns;
c) after cleaning of the separation and detection systems;
d) if the deviation of an injected calibration standard exceeds 20 %.
The relative response factor for congener i is defined and calculated as given in Formula (1):
12 13
   
A C c C
i i
   
   
rrf =⋅ (1)
i
13 12
   
A C c C
i i
   
   
where
rrf is the relative response factor of native congener i relative to C -labelled congener i;
i 12
A [ C] is the area of native congener i;
i
13 13
A [ C] is the area of C -labelled congener i;
i 12
c [ C] is the concentration of native congener i in the calibration solution;
i
13 13
c [ C]is the concentration of C -labelled congener i in the calibration solution.
i 12
9.6.3 Calibration for sum of homologue groups
The calibration of the mass spectrometer is done in the same way and with the same calibration solutions
as for single congeners. The relative response factors for each homologue group is calculated by the
addition of all peak areas of all native congeners of the same homologue group which are included in the
calibration solution relative to one C -labelled congener. Table 6 shows the relations between native
congeners and C -labelled congeners.
Table 6 — Relation for calibration of homologue groups
Calibration of Calibration of
PCDD homologues PCDF homologues
Substance
13 13
Native isomer C isomer Native isomer C isomer
Tetrachloro homologues 2,3,7,8 2,3,7,8 2,3,7,8 2,3,7,8
1,2,3,7,8 1,2,3,7,8 1,2,3,7,8 1,2,3,7,8
Pentachloro homologues
2,3,4,7,8
1,2,3,4,7,8 1,2,3,7,8,9
...