ISO 17858:2007

Water quality — Determination of dioxin-like polychlorinated biphenyls — Method using gas chromatography/mass spectrometry

ISO 17858:2007 specifies a method for the determination of dioxin-like tetra- to hepta-chlorinated biphenyls (PCBs) in waters and wastewaters (containing less than 1 % suspended solids) using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The minimum levels at which the dioxin-like PCBs can typically be determined with no interferences present are specified. This method is "performance based". The analyst is permitted to modify the method to overcome interferences or lower the cost of measurements, provided that all performance criteria in this method are met. The requirements for establishing method equivalency are given.

Qualité de l'eau — Dosage des biphényls polychlorés de type dioxine — Méthode par chromatographie en phase gazeuse/spectrométrie de masse

Kakovost vode - Določevanje dioksinu podobnih polikloriranih bifenilov - Metoda s plinsko kromatografijo z masno selektivnim detektorjem

Ta mednarodni standard določa metodo določevanja dioksinu podobnih tetra- do hepta- kloriranih bifenilov (PCB) v vodah in odpadnih vodah (ki vsebujejo manj kot 1 % neraztopljenih trdnih snovi) z plinsko kromatografijo visoke ločljivosti/masno spektrometrijo visoke ločljivosti (HRGC/HRMS). Metoda je optimizirana za dioksinu podobne PBS, vendar lahko vključuje druge koplanarne sestavine, kot so poliklorirani dioksini in furani (PCDD/PCDF) in poliklorirani naftaleni (PNC). Ta metoda se lahko uporablja za določevanje dioksinu podobnih PCB in drugih matric (npr. živih organizmov, sedimentov, zraka); vendar se lahko zahtevajo dodatni koraki temeljitega čiščenja in tehnike za vzorce z visoko organsko obremenitvijo. Ta metoda se uporablja za dvanajst PCB, ki niso orto ali so mono-orto, ki jih je določila Svetovna zdravstvena organizacija , kot tudi za druge PCB in koplanarne spojine. Meje detekcije in ravni količinske določitve v tej metodi zavisijo od ravni interferenc in instrumentalnih omejitev. Minimalne ravni (ML) iz preglednice 2 so ravni, pri katerih so  lahko dioksinu podobni PCB praviloma določeni brez prisotnih interferenc.
Ta metoda je »osnovana na učinkovitosti«. Analitik lahko spremeni metodo, da premaga interference ali zniža strošek merjenj, pod pogojem, da so izpolnjena vsa merila za učinkovitost pri tej metodi. Zahteve za dokazovanje enakovrednosti metode so podane v točki 9.2.

General Information

• Status: Published
• Publication Date: 11-Feb-2007
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: ISO/TC 147/SC 2 - Physical, chemical and biochemical methods
• Drafting Committee: ISO/TC 147/SC 2 - Physical, chemical and biochemical methods
• Current Stage: 9020 - International Standard under periodical review
• Start Date: 15-Jan-2026
• Completion Date: 15-Jan-2026
• Ref Project: SIST ISO 17858:2010 - Water quality - Determination of dioxin-like polychlorinated biphenyls - Method using gas chromatography/mass spectrometry

Overview

ISO 17858:2007 (ISO 17858:2007) specifies a laboratory method for the determination of dioxin-like polychlorinated biphenyls (PCBs) in waters and wastewaters (matrices containing less than 1% suspended solids) using high-resolution gas chromatography / high-resolution mass spectrometry (HRGC/HRMS). The standard covers sample preparation through final quantification, defines minimum levels at which dioxin-like PCBs can typically be determined (when no interferences are present), and sets out performance criteria and requirements for establishing method equivalency. The method is explicitly performance-based, allowing analysts to adapt procedures to overcome interferences or reduce costs provided all performance criteria are met.

Key Topics and Technical Requirements

• Target analytes: Dioxin-like tetra- to hepta-chlorinated biphenyl congeners.
• Scope of matrices: Surface water, groundwater and wastewater with <1% suspended solids.
• Analytical workflow:
  • Spiking and extraction (SPE, separatory funnel, Soxhlet where applicable)
  • Clean-up (GPC, silica/alumina/carbon columns, HPLC, florisil options)
  • Concentration and solvent exchange (macro- and micro-concentration)
  • HRGC/HRMS analysis for identification and quantification
• Calibration and quantification:
  • Isotope-dilution calibration, internal standard methods, or combined approaches
  • Ion abundance ratios, retention time criteria, and mass spectrometer resolution requirements
• Quality assurance / quality control (QA/QC):
  • Initial precision and recovery (IPR), method blanks, recovery checks, QC samples
  • System and laboratory performance checks, calibration verification, limits of detection/quantification described as minimum levels under non-interfering conditions
• Reporting: Congener-specific results, concentration in sample, and calculation of toxic equivalents (TEQ) where applicable.
• Performance-based flexibility: Modifications permitted if method equivalency and performance criteria are demonstrated.

Applications - Who Uses This Standard

• Environmental and commercial laboratories performing contaminant screening of water and wastewater
• Regulatory agencies and enforcement bodies assessing PCB contamination and compliance
• Water utilities and wastewater treatment operators monitoring discharges
• Environmental consultants and researchers conducting pollution assessment, source identification and TEQ-based risk assessments

Related Standards (if applicable)

• ISO/TC 147 series standards on water quality (method development and sampling guidance)
• ISO sampling standards (e.g., ISO 5667 series) for representative water sampling practices Note: Users should consult the normative references listed in ISO 17858 for full inter-laboratory and sampling context.

Keywords: ISO 17858, water quality, dioxin-like PCBs, HRGC/HRMS, gas chromatography mass spectrometry, isotope dilution, wastewater analysis, environmental monitoring.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2010
.DNRYRVWYRGH'RORþHYDQMHGLRNVLQXSRGREQLKSROLNORULUDQLKELIHQLORY0HWRGDV
SOLQVNRNURPDWRJUDILMR]PDVQRVHOHNWLYQLPGHWHNWRUMHP
Water quality - Determination of dioxin-like polychlorinated biphenyls - Method using gas
chromatography/mass spectrometry
Qualité de l'eau - Dosage des biphényls polychlorés de type dioxine - Méthode par
chromatographie en phase gazeuse/spectrométrie de masse
Ta slovenski standard je istoveten z: ISO 17858:2007
ICS:
13.060.50 3UHLVNDYDYRGHQDNHPLþQH Examination of water for
VQRYL chemical substances
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 17858
First edition
2007-02-15
Water quality — Determination of dioxin-
like polychlorinated biphenyls — Method
using gas chromatography/mass
spectrometry
Qualité de l'eau — Dosage des biphényls polychlorés de type
dioxine — Méthode par chromatographie en phase
gazeuse/spectrométrie de masse

Reference number
©
ISO 2007
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ii © ISO 2007 – All rights reserved

Contents Page
Foreword. vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions. 2
3.2 Abbreviated terms . 3
4 Principle. 4
4.1 Spiking and extraction . 4
4.2 Clean-up. 4
4.3 Concentration. 4
4.4 Identification. 5
4.5 Quantification. 5
4.6 Analytical quality . 5
5 Contamination and interferences. 5
6 Reagents and standards . 6
7 Apparatus and materials. 10
7.1 Sampling equipment for discrete sampling. 10
7.2 Equipment for sample preparation . 11
7.3 Extraction apparatus . 11
7.4 Filtration apparatus . 12
7.5 Clean-up apparatus . 12
7.6 Concentration apparatus . 13
7.7 Other equipment . 13
8 Sample collection, preservation, storage and holding times . 14
9 Quality assurance (QA)/quality control (QC) . 14
9.1 General. 14
9.2 Initial precision and recovery (IPR). 15
9.3 Spiking . 15
9.4 Recovery of labelled compounds assessment. 16
9.5 Method blanks. 16
9.6 QC check sample. 16
9.7 Method precision . 16
10 Calibration . 17
10.1 Operating conditions. 17
10.2 Mass spectrometer (MS) resolution. 17
10.3 Ion abundance ratios, minimum levels, signal-to-noise ratios, and absolute retention
times. 17
10.4 Retention time . 18
10.5 Isomer specificity. 18
10.6 Calibration by isotope dilution. 18
10.7 Calibration by internal standard. 19
10.8 Combined calibration . 19
11 Sample preparation . 20
11.1 General. 20
11.2 Determination of percent suspended solids . 20
11.3 Preparation of aqueous samples containing 1 % of suspended solids or less . 21
12 Extraction and concentration . 22
12.1 Separatory funnel extraction of filtrates and of aqueous samples that are visibly absent of
particles. 22
12.2 Solid-phase extraction (SPE) of samples containing less than 1 % suspended solids . 22
12.3 Soxhlet extraction of filters and/or disks . 23
12.4 Back-extraction with acid and base . 24
12.5 Macro-concentration. 24
12.6 Micro-concentration and solvent exchange. 26
13 Extract clean-up . 26
13.1 General . 26
13.2 Gel permeation chromatography (GPC) . 27
13.3 Silica clean-up . 28
13.4 Alumina clean-up . 28
13.5 Carbon column. 29
13.6 High performance liquid chromatography (HPLC). 29
13.7 Florisil clean-up. 30
13.8 Silver nitrate/silica column. 31
14 HRGC/HRMS analysis. 31
15 System and laboratory performance . 31
15.1 General . 31
15.2 MS resolution. 31
15.3 Calibration verification . 31
15.4 GC resolution. 32
15.5 Blank. 32
16 Qualitative determination. 32
17 Quantitative determination. 32
17.1 Isotope dilution quantification. 32
17.2 Internal standard quantification and labelled-compound recovery. 33
17.3 Concentration in sample . 34
17.4 Results and reporting . 35
17.5 Toxic equivalents (TEQ) . 35
18 Analysis of complex samples. 36
18.1 General . 36
18.2 Recovery of labelled compounds. 36
19 Pollution prevention . 36
20 Waste management . 37
21 Precision . 37
Annex A (informative) Example chromatograms . 45
Annex B (informative) Use of HRGC/LRMS. 47
Annex C (informative) Precision data. 50
Bibliography . 54

Table 1 — Dioxin-like PCBs determined by this method . 38
Table 2 — Suggested quantification relationships. 39
Table 3 — Suggested calibration standard concentrations . 40
Table 4 — Suggested concentration of dioxin-like PCBs in stock and spiking solutions. 41
Table 5 — Typical GC columns and temperature programs . 42
iv © ISO 2007 – All rights reserved

Table 6 — Examples of toxic equivalent factors . 43
Table 7 — Congener function groups and ions. 44
Table B.1 — TetraCBs . 49
Table B.2 — PentaCBs . 49
Table B.3 — HexaCBs. 49
Table B.4 — HeptaCBs . 49
Table C.1 — Spiking amounts transferred to sample bottles . 50
Table C.2 — Samples 1 and 2 (fortified industrial effluent) — Statistical summary. 51
Table C.3 — Sample 3 (unfortified industrial effluent) — Statistical summary. 52
Table C.4 — Sample 4 (HPLC water) — Statistical summary. 53

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 17858 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical,
chemical and biochemical methods.

vi © ISO 2007 – All rights reserved

Introduction
When using this International Standard, it may be necessary in some cases to determine whether and to what
extent particular problems will require the specification of minor additional conditions.

INTERNATIONAL STANDARD ISO 17858:2007(E)

Water quality — Determination of dioxin-like polychlorinated
biphenyls — Method using gas chromatography/mass
spectrometry
WARNING — Persons using this International Standard should be familiar with normal 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.
Attention is drawn to any relevant national safety regulations. The non-ortho and mono-ortho PCBs
are co-planar and are among the most toxic of chemicals. All work with dioxin-like PCBs requires
therefore the utmost care; the national safety measures which correspond to those for toxic
substances shall be strictly adhered to.
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 the determination of dioxin-like tetra- to hepta-chlorinated
biphenyls (PCBs) in waters and wastewaters (containing less than 1 % suspended solids) using
high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The method is
optimized for dioxin-like PCBs, but can include other co-planar compounds such as polychlorinated dioxins
and furans (PCDDs/PCDFs) and polychlorinated naphthalenes (PCNs). This method can be used to
determine dioxin-like PCBs in other matrices (e.g. biota, sediments, air); however, additional clean-up steps
and techniques can be required for samples with high organic loadings.
This method is applicable to the twelve non- and mono-ortho PCBs designated by the World Health
Organization, as well as to other PCBs and co-planar compounds.
The detection limits and quantification levels in this method are dependent on the level of interferences as well
as instrumental limitations. The minimum levels (ML) in Table 2 are the levels at which the dioxin-like PCBs
can typically be determined with no interferences present.
This method is “performance based”. The analyst is permitted to modify the method to overcome interferences
or lower the cost of measurements, provided that all performance criteria in this method are met. The
requirements for establishing method equivalency are given in 9.2.
2 Normative references
The following referenced documents are indispensable for the application 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 3696, Water for analytical laboratory use — Specification and test methods
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-2, Water quality — Sampling — Part 2: Guidance on sampling techniques
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
analyte
dioxin-like polychlorinated biphenyl tested for by this method
See Table 1.
3.1.2
calibration standard
solution prepared from a secondary standard and/or stock solutions and used to calibrate the response of the
instrument with respect to analyte concentration
3.1.3
calibration verification standard
VER
midpoint calibration standard that is used to verify calibration
3.1.4
certified reference material
CRM
quality control sample used to determine accuracy and precision of method
3.1.5
congener
member of the same kind, class or group
EXAMPLE Any one of the 209 individual PCBs.
3.1.6
critical pair
pair of isomers that must be separated to a predefined degree (e.g. 25 % valley) to ensure chromatographic
separation meets minimum quality criteria
3.1.7
dioxin-like isomer
PCB with identical chemical composition but different structure
3.1.8
homologue group
complete group of isomers
EXAMPLE Tetrachlorobiphenyls.
3.1.9
isotope dilution
method using labelled (usually C ) internal standards to correct for losses during sample preparation and
analysis
3.1.10
keeper solvent
high boiling point solvent added to the sampling standard solution
2 © ISO 2007 – All rights reserved

3.1.11
method blank
aliquot of reagent water that is treated exactly as a sample through the complete analytical procedure
including extraction, clean-up, identification and quantification including all the relevant reagents and materials
3.1.12
operational performance characteristics
influence of the physical and chemical environment and maintenance problems, for example, mains voltage,
temperature, supply of certain substances, set-up time, period of unattended operation
3.1.13
pattern
chromatographic fingerprint of any series of PCB isomers
3.1.14
profile
graphic representation of the sums of the isomer concentrations of the PCBs
3.1.15
spiking
addition of C -labelled PCB standards of which the recovery is calculated and used to correct values of
native analytes of interest
3.1.16
statistical performance characteristics
quantification, for measured values, of the possible deviations resulting from the random part of the measuring
process, e.g. repeatability or instability
3.1.17
toxic equivalent factor
TEF
relative toxicity to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
3.1.18
toxic equivalent quantity
TEQ
sum of toxic equivalents of each individual congener
3.2 Abbreviated terms
CRM certified reference material
GC/MS gas chromatography/mass spectrometry
GPC gel permeation chromatography
HPLC high-performance liquid chromatography
HRGC high-resolution gas chromatography
HRMS high-resolution mass spectrometry
IPR initial precision and recovery
LRMS low-resolution mass spectrometry
MDL method detection limit
ML minimum level (see Table 2)
PAR precision and recovery
PCB polychlorinated biphenyl
PCDD/PCDF polychlorinated dibenzo-p-dioxin/dibenzofuran
PCN polychlorinated naphthalene
PFK perfluorokerosene
SIM selected ion monitoring
SPE solid-phase extraction
TEF toxic equivalent factor
TEQ toxic equivalent quantity
VER calibration verification standard
4 Principle
4.1 Spiking and extraction
Stable isotopically labelled analogues of dioxin-like PCBs (diluted in a suitable solvent such as acetone) are
spiked into a 1 litre aqueous sample (a sample containing less than 1 % suspended solids). A minimum of one
labelled standard per homologue group is used and the sample is extracted by one of three procedures noted
in 4.1 a), 4.1 b) and 4.1 c). If the sample contains more than 1 % solid material, the solid portion can be
analysed directly after filtration or drying and the aqueous portion can be discarded.
a) Samples containing no visible particles are extracted with dichloromethane [6.4 f)] in a separatory funnel
or by solid-phase extraction. The extract is concentrated for clean-up.
b) Samples containing visible particles are vacuum filtered through a glass-fibre filter. The filter is extracted
in a Soxhlet extractor using toluene and the filtrate is extracted with dichloromethane [6.4 f)] in a
separatory funnel. The dichloromethane extract is concentrated and combined with the Soxhlet extract
prior to clean-up.
c) The sample is vacuum filtered through a glass-fibre filter on top of a solid-phase extraction (SPE) disk.
The filter and disk are eluted with suitable solvent mixtures or extracted in a Soxhlet or pressure filtration
extractor, and the extract is concentrated for clean-up.
Other solvents and extraction techniques may be substituted, provided that all the performance criteria can be
met.
4.2 Clean-up
After extraction, sample extracts are cleaned to remove interfering components. Sample clean-up procedures
1)
can include washes with acid and/or base, gel permeation, alumina, silica, Florisil and activated carbon
chromatography. High-performance liquid chromatography (HPLC) can be used for further isolation of other
specific co-planar compounds if required. Due to the large number of potential interfering compounds, sample
extracts shall be fractioned or analysed on at least two distinct GC column phases to ensure unique
identification and accurate quantification of each dioxin-like PCB congener.
4.3 Concentration
After clean-up, the extract(s) is concentrated to near dryness. Prior to injection, recovery standards are added
to each extract, and an aliquot of the extract is injected into the gas chromatograph. The analytes are
separated by GC and detected by a high-resolution mass spectrometer. Two exact masses are monitored for
each analyte.
1) Florisil 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 2007 – All rights reserved

Resolution greater than or equal to 10 000 is recommended. High-resolution gas chromatography/high-
resolution mass spectrometry at a resolution greater than or equal to 10 000 is at present required to achieve
adequate sensitivity and selectivity, and to allow the use of all C -labelled standards. If the sample extract
is being analysed for multi-component analyte groups (PCDD/Fs, PCBs, PCNs), a resolution of 10 000 is
necessary. At resolutions less than 10 000, some C PCDFs and PCBs interfere with native PCDDs of the
same level of chlorination. Resolutions less than 10 000 can be used for specific analyte groups (PCBs,
PCNs) where the matrix and potential interferences are well characterized.
4.4 Identification
An individual dioxin-like PCB is identified by comparing the GC retention time and ion abundance ratio of two
exact masses monitored (see Table 7) with the corresponding retention time of an authentic internal standard
and the theoretical or acquired ion-abundance ratio of the two exact masses. The isomers and congeners for
which there are no labelled analogues are identified when retention times or relative retention times and
ion-abundance ratios agree within predefined limits. Masses of those PCBs with a degree of chlorination
higher than three (e.g. PentaCB 110 for TetraCB 77) shall be monitored to ensure there is no contribution to
the mass of interest.
4.5 Quantification
Quantitative analysis is performed using selected ion monitoring (SIM) areas, in one of two ways.
a) For the dioxin-like PCBs for which labelled analogues have been added to the sample (4.1), the GC/MS
system is calibrated, and the concentration of each compound is determined using the isotope dilution
technique.
b) For the dioxin-like PCBs for which labelled analogues are not added, the GC/MS system is calibrated for
each compound using an isomer or congener with the most similar structure and the concentration of
each compound is determined using the internal standard technique.
4.6 Analytical quality
The quality of the analysis is assured through reproducible calibration and testing of the extraction, clean-up,
and GC/MS systems. Interferences, biases and limitations should be determined and identified for each target
analyte through intercalibration (interlaboratory) studies, certified reference materials (CRM) and spiked matrix
samples (SMS). A series of quality control (QC) samples (CRM, SMS) should be analysed with each set of
samples and monitored through control charting or other quality review procedures.
5 Contamination and interferences
5.1 Where possible, monitor or clean reagents by extraction or solvent rinse.
Solvents, reagents, labware, and other sample processing hardware can yield artefacts and/or elevated
baselines causing misinterpretation of chromatograms. (Example chromatograms showing typical retention
times of native and labelled PCBs are given in Annex A.) Specific selection of reagents and purification of
solvents by distillation in all-glass systems can be required. Many reagents, solvents and labware contain
background levels of dioxin-like compounds, e.g. PCB118 and PCB105.
5.2 Clean labware such that the method blank requirements given in 9.5.3 are met. An example of a
cleaning procedure is given below in a) to c).
a) Disassemble labware with removable parts, particularly separatory funnels with fluoropolymer stopcocks,
prior to detergent washing. Rinse labware with solvent and wash with a detergent solution as soon after
use as is practical. Sonication of labware containing a detergent solution for approximately 30 s can aid in
cleaning.
b) After detergent washing, rinse labware immediately with hot tap water. The tap water rinse shall be
followed by an acetone rinse, then a dichloromethane [6.4 f)] rinse/soak. For known contaminated
labware, use toluene as a final rinse/soak.
c) SoxhIet apparatus should be cycled with toluene for at least 20 cycles. Shake separatory funnels with
dichloromethane [6.4 f)] and/or toluene for 2 min, drain, and then shake with pure dichloromethane [6.4 f)]
for 2 min.
Proper cleaning of labware is extremely important because labware can contaminate the samples but can also
remove the analytes of interest by surface adsorption if the surface is activated during the cleaning procedure.
Glassware can be checked for contamination by analysing solvent rinses.
5.3 Demonstrate that all materials used in the analysis are free from interferences by running reference
matrix method blanks initially and with each sample batch (samples started through the extraction process on
a given 12-h shift, to a maximum of 20 samples); see 9.5, 15.5.
5.4 The reference matrix shall simulate, as closely as possible, the sample matrix under test. Ideally, the
reference matrix shall not contain dioxin-like compounds in detectable amounts, but shall contain potential
interferants in the concentrations expected to be found in the samples to be analysed.
Interferences co-extracted from samples can vary considerably from source to source, depending on the
diversity of the site being sampled. Interfering compounds, including PCBs of higher degrees of chlorination
can be present at concentrations several orders of magnitude higher than the dioxin-like PCBs being analysed.
The most frequently encountered interferences are dibenzo-p-dioxins, dibenzofurans, diphenyl ethers,
methoxy biphenyls, hydroxydiphenyl ethers, benzylphenyl ethers, aromatic sulfur compounds, polynuclear
aromatics, and pesticides. Because very low levels of dioxin-like PCBs are measured by this method, the
elimination of interferences is essential. The example clean-ups given in Clause 13 can be used to reduce or
eliminate these interferences and thereby permit reliable determination of the dioxin-like PCBs at the levels
shown in Table 2.
5.5 When a clean reference matrix that simulates the sample matrix under test is not available, use reagent
water (6.7) or a matrix that most closely resembles the sample.
5.6 Number each piece of reusable labware or minimally identify each set of specific type of labware (e.g.
Soxhlet extractors, round-bottom flasks) to associate that specific labware with the processing of a particular
sample or set of samples. This will assist the laboratory in tracking possible sources of contamination for
individual samples, identifying labware associated with highly contaminated samples that may require extra
cleaning, and determining when labware shall be discarded.
6 Reagents and standards
Use only reagents of recognized analytical grade, unless otherwise specified.
6.1 Water, complying with grade 3 as defined in ISO 3696.
6.2 pH adjustment and back-extraction reagents.
6.2.1 Potassium hydroxide solution.
Dissolve 20 g of potassium hydroxide, KOH, in 100 ml of water.
6.2.2 Sulfuric acid, H SO , ρ = 1,84 g/ml.
2 4
6.2.3 1 mol/l sulfuric acid.
Dilute with care 56 ml of concentrated sulfuric acid (6.2.2) to 1 litre of water (6.1).
6.2.4 Sodium chloride solution.
Dissolve 5 g of sodium chloride, NaCl, in 100 ml of water.
6.2.5 Sodium thiosulfate, Na S O .
2 2 3
6 © ISO 2007 – All rights reserved

6.3 Solution drying and evaporation reagents.
6.3.1 Sodium sulfate, Na SO , granular, anhydrous.
2 4
Bake at 300 °C for at least 24 h, cool in a desiccator, and store in a precleaned glass bottle with a screw cap
that prevents moisture from entering.
If, after heating, the sodium sulfate develops a noticeable greyish cast (due to the presence of carbon in the
crystal matrix), discard that batch of reagent as it is not suitable for use. Rinse with about 20 ml of
dichloromethane [6.4 f)] per gram of Na SO or extract with dichloromethane [6.4 f)] if background
2 4
contamination is detected.
6.3.2 Prepurified nitrogen, N 99,999 %.
6.4 Solvents for extraction and clean-up.
The extraction and clean-up solvents, distilled in glass, of pesticide quality and free of interferences, include
the following:
a) Acetone, C H O.
3 6
b) Toluene, C H .
7 8
c) Cyclohexane, C H .
6 12
d) Hexane, C H .
6 14
e) Methanol, CH OH.
f) Dichloromethane, CH Cl .
2 2
g) Diethyl ether, C H O.
4 10
h) Ethanol, C H O.
2 6
i) Nonane, C H .
9 20
6.5 GPC calibration solution.
Dissolve 300 mg/ml of corn oil, 15 mg/ml of bis(2-ethylhexyl) phthalate, C H O, 1,4 mg/ml of
24 38 4
pentachlorophenol, C Cl OH, 0,1 mg/ml of perylene, C H , and 0,5 mg/ml of sulfur, S, in dichloromethane
6 5 20 12
[6.4 f)]. Store in glass and keep refrigerated. Prepare fresh monthly.
6.6 Adsorbents for sample clean-up.
6.6.1 Silica, 70 µm to 230 µm.
6.6.1.1 Activated silica, baked at 180 °C for a minimum of 1 h, cooled in a desiccator, and stored in a
precleaned glass bottle with a screw cap that prevents moisture from entering. Prepare fresh every two weeks.
6.6.1.2 Acid silica, 30 % mass fraction.
Thoroughly mix 44,0 g of sulfuric acid (6.2.2) with 100 g of activated silica in a clean container. Break up
aggregates with a stirring rod until a uniform mixture is obtained. Store in a bottle with a fluoropolymer-lined
screw cap. 22 % acid silica and 44 % acid silica are prepared in a similar manner by adding 29 g and 80 g of
sulfuric acid, respectively, to 100 g of activated silica. Prepare fresh every two weeks.
6.6.1.3 Basic silica.
Thoroughly mix 30 g of 1 mol/l sodium hydroxide solution [c(NAOH) = 1 mol/l] with 100 g of activated silica in
a clean container. Break up aggregates with a stirring rod until a uniform mixture is obtained. Store in a bottle
with a fluoropolymer-lined screw cap. Prepare fresh every two weeks.
6.6.1.4 Potassium silicate, 36 % mass fraction.
Dissolve 56 g of high purity potassium hydroxide (6.2.1) in 300 ml of methanol [6.4 e)] in a 750 ml to 1 000 ml
flat-bottom flask. Add 100 g of silica (6.6.1) and a stirring bar, and stir on a hotplate at 60 °C to 70 °C for 1 h to
2 h. Decant the liquid and rinse the potassium silicate twice with 100 ml portions of methanol, followed by a
single rinse with 100 ml of dichloromethane [6.4 f)]. Spread the potassium silicate on solvent-rinsed aluminium
foil and dry for 2 h to 4 h in a hood. Activate overnight at 200 °C to 250 °C. Store in a bottle with a
fluoropolymer-lined screw cap. Prepare fresh every two weeks.
6.6.2 Alumina.
6.6.2.1 One of two types of alumina, acid or basic, can be used in the clean-up of sample extracts,
provided that the laboratory can meet the performance specifications for the recovery of labelled compounds
described in 9.4. The same type of alumina shall be used for all samples, including those used to demonstrate
initial precision and recovery (9.2).
a) Acid alumina, activate by heating to 130 °C for a minimum of 12 h.
b) Basic alumina, activate by heating to 600 °C for a minimum of 24 h.
6.6.2.2 Alternatively, activate by heating in a tube furnace at 650 °C to 700 °C under an airflow rate of
approximately 400 ml/min. Do not heat over 700 °C, as this can lead to reduced capacity for retaining the
analytes. Store at 130 °C in a covered flask. Use within 5 d of baking.
2)
ICN Alumina Super I or an equivalent may be used without activation.
6.6.3 Activated carbon.
3)
6.6.3.1 Mixture of carbon and silica, for example, Carbopak C (e.g. Supelco 1-0258, or equivalent)
4)
and Celite 545 (e.g. Supelco 2-0199, or equivalent).
Thoroughly mix 9,0 g of Carbopak C and 41,0 g of Celite 545 to produce a mass fraction of 18 % of the
mixture. Activate the mixture at 130 °C for at least 6 h. Store in a desiccator. Prepare fresh every two weeks.
5)
NOTE Active carbon-impregnated silica (Wako Pure Chemical Industries 019-11941) and active carbon-dispersed
6)
silica gel (Kanto Chemical Co. 01875-43) are examples of alternative materials.
7)
6.6.3.2 Carbon, e.g. Amoco PX21 .
Thoroughly mix 0,30 g of PX21 with 5,7 g of activated silica (6.6.1.1) in a vial. Cap and shake the vial for at
least 2 min or until mixture is homogeneous. Remove cap and place vial in oven at 300 °C for at least 60 h.
Store in a desiccator.
2) ICN Alumina Super I 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.
3) Carbopak C 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) Celite 545 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.
5) Active carbon-impregnated silica (019-11941) from Wako Pure Chemical Industries 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.
6) Active carbon-dispersed silica gel (01875-43) from Kanto Chemical Company 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.
7) Amoco PX21 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.
8 © ISO 2007 – All rights reserved

6.6.4 Florisil, 70 µm to 250 µm.
Activate in an oven above 130 °C for a minimum of 24 h. Use as soon as possible after removal from oven.
Activity of Florisil can be dependant on relative humidity. Prepare fresh for each use.
6.6.5 Silver nitrate/silica, (10 % mass fraction) for elimination of organosulfur and organohalogen
compounds, made of silver nitrate (AgNO ) of AR (Analytical Reagent) grade or equivalent and silica (6.6.1).
Dissolve 10 g of silver nitrate in 40 ml of water, add in portions 90 g of silica and shake until the mixture is
homogeneous. Let stand for 30 min. Transfer the mixture to a drying oven preheated to 70 °C and heat from
70 °C to 125 °C over a 2 h period. Activate at 125 °C for at least 10 h. Store the mixture in a brown glass
bottle. Prepare fresh for e
...

INTERNATIONAL ISO
STANDARD 17858
First edition
2007-02-15
Water quality — Determination of dioxin-
like polychlorinated biphenyls — Method
using gas chromatography/mass
spectrometry
Qualité de l'eau — Dosage des biphényls polychlorés de type
dioxine — Méthode par chromatographie en phase
gazeuse/spectrométrie de masse

Reference number
©
ISO 2007
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ii © ISO 2007 – All rights reserved

Contents Page
Foreword. vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions. 2
3.2 Abbreviated terms . 3
4 Principle. 4
4.1 Spiking and extraction . 4
4.2 Clean-up. 4
4.3 Concentration. 4
4.4 Identification. 5
4.5 Quantification. 5
4.6 Analytical quality . 5
5 Contamination and interferences. 5
6 Reagents and standards . 6
7 Apparatus and materials. 10
7.1 Sampling equipment for discrete sampling. 10
7.2 Equipment for sample preparation . 11
7.3 Extraction apparatus . 11
7.4 Filtration apparatus . 12
7.5 Clean-up apparatus . 12
7.6 Concentration apparatus . 13
7.7 Other equipment . 13
8 Sample collection, preservation, storage and holding times . 14
9 Quality assurance (QA)/quality control (QC) . 14
9.1 General. 14
9.2 Initial precision and recovery (IPR). 15
9.3 Spiking . 15
9.4 Recovery of labelled compounds assessment. 16
9.5 Method blanks. 16
9.6 QC check sample. 16
9.7 Method precision . 16
10 Calibration . 17
10.1 Operating conditions. 17
10.2 Mass spectrometer (MS) resolution. 17
10.3 Ion abundance ratios, minimum levels, signal-to-noise ratios, and absolute retention
times. 17
10.4 Retention time . 18
10.5 Isomer specificity. 18
10.6 Calibration by isotope dilution. 18
10.7 Calibration by internal standard. 19
10.8 Combined calibration . 19
11 Sample preparation . 20
11.1 General. 20
11.2 Determination of percent suspended solids . 20
11.3 Preparation of aqueous samples containing 1 % of suspended solids or less . 21
12 Extraction and concentration . 22
12.1 Separatory funnel extraction of filtrates and of aqueous samples that are visibly absent of
particles. 22
12.2 Solid-phase extraction (SPE) of samples containing less than 1 % suspended solids . 22
12.3 Soxhlet extraction of filters and/or disks . 23
12.4 Back-extraction with acid and base . 24
12.5 Macro-concentration. 24
12.6 Micro-concentration and solvent exchange. 26
13 Extract clean-up . 26
13.1 General . 26
13.2 Gel permeation chromatography (GPC) . 27
13.3 Silica clean-up . 28
13.4 Alumina clean-up . 28
13.5 Carbon column. 29
13.6 High performance liquid chromatography (HPLC). 29
13.7 Florisil clean-up. 30
13.8 Silver nitrate/silica column. 31
14 HRGC/HRMS analysis. 31
15 System and laboratory performance . 31
15.1 General . 31
15.2 MS resolution. 31
15.3 Calibration verification . 31
15.4 GC resolution. 32
15.5 Blank. 32
16 Qualitative determination. 32
17 Quantitative determination. 32
17.1 Isotope dilution quantification. 32
17.2 Internal standard quantification and labelled-compound recovery. 33
17.3 Concentration in sample . 34
17.4 Results and reporting . 35
17.5 Toxic equivalents (TEQ) . 35
18 Analysis of complex samples. 36
18.1 General . 36
18.2 Recovery of labelled compounds. 36
19 Pollution prevention . 36
20 Waste management . 37
21 Precision . 37
Annex A (informative) Example chromatograms . 45
Annex B (informative) Use of HRGC/LRMS. 47
Annex C (informative) Precision data. 50
Bibliography . 54

Table 1 — Dioxin-like PCBs determined by this method . 38
Table 2 — Suggested quantification relationships. 39
Table 3 — Suggested calibration standard concentrations . 40
Table 4 — Suggested concentration of dioxin-like PCBs in stock and spiking solutions. 41
Table 5 — Typical GC columns and temperature programs . 42
iv © ISO 2007 – All rights reserved

Table 6 — Examples of toxic equivalent factors . 43
Table 7 — Congener function groups and ions. 44
Table B.1 — TetraCBs . 49
Table B.2 — PentaCBs . 49
Table B.3 — HexaCBs. 49
Table B.4 — HeptaCBs . 49
Table C.1 — Spiking amounts transferred to sample bottles . 50
Table C.2 — Samples 1 and 2 (fortified industrial effluent) — Statistical summary. 51
Table C.3 — Sample 3 (unfortified industrial effluent) — Statistical summary. 52
Table C.4 — Sample 4 (HPLC water) — Statistical summary. 53

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 17858 was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical,
chemical and biochemical methods.

vi © ISO 2007 – All rights reserved

Introduction
When using this International Standard, it may be necessary in some cases to determine whether and to what
extent particular problems will require the specification of minor additional conditions.

INTERNATIONAL STANDARD ISO 17858:2007(E)

Water quality — Determination of dioxin-like polychlorinated
biphenyls — Method using gas chromatography/mass
spectrometry
WARNING — Persons using this International Standard should be familiar with normal 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.
Attention is drawn to any relevant national safety regulations. The non-ortho and mono-ortho PCBs
are co-planar and are among the most toxic of chemicals. All work with dioxin-like PCBs requires
therefore the utmost care; the national safety measures which correspond to those for toxic
substances shall be strictly adhered to.
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 the determination of dioxin-like tetra- to hepta-chlorinated
biphenyls (PCBs) in waters and wastewaters (containing less than 1 % suspended solids) using
high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The method is
optimized for dioxin-like PCBs, but can include other co-planar compounds such as polychlorinated dioxins
and furans (PCDDs/PCDFs) and polychlorinated naphthalenes (PCNs). This method can be used to
determine dioxin-like PCBs in other matrices (e.g. biota, sediments, air); however, additional clean-up steps
and techniques can be required for samples with high organic loadings.
This method is applicable to the twelve non- and mono-ortho PCBs designated by the World Health
Organization, as well as to other PCBs and co-planar compounds.
The detection limits and quantification levels in this method are dependent on the level of interferences as well
as instrumental limitations. The minimum levels (ML) in Table 2 are the levels at which the dioxin-like PCBs
can typically be determined with no interferences present.
This method is “performance based”. The analyst is permitted to modify the method to overcome interferences
or lower the cost of measurements, provided that all performance criteria in this method are met. The
requirements for establishing method equivalency are given in 9.2.
2 Normative references
The following referenced documents are indispensable for the application 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 3696, Water for analytical laboratory use — Specification and test methods
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-2, Water quality — Sampling — Part 2: Guidance on sampling techniques
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
analyte
dioxin-like polychlorinated biphenyl tested for by this method
See Table 1.
3.1.2
calibration standard
solution prepared from a secondary standard and/or stock solutions and used to calibrate the response of the
instrument with respect to analyte concentration
3.1.3
calibration verification standard
VER
midpoint calibration standard that is used to verify calibration
3.1.4
certified reference material
CRM
quality control sample used to determine accuracy and precision of method
3.1.5
congener
member of the same kind, class or group
EXAMPLE Any one of the 209 individual PCBs.
3.1.6
critical pair
pair of isomers that must be separated to a predefined degree (e.g. 25 % valley) to ensure chromatographic
separation meets minimum quality criteria
3.1.7
dioxin-like isomer
PCB with identical chemical composition but different structure
3.1.8
homologue group
complete group of isomers
EXAMPLE Tetrachlorobiphenyls.
3.1.9
isotope dilution
method using labelled (usually C ) internal standards to correct for losses during sample preparation and
analysis
3.1.10
keeper solvent
high boiling point solvent added to the sampling standard solution
2 © ISO 2007 – All rights reserved

3.1.11
method blank
aliquot of reagent water that is treated exactly as a sample through the complete analytical procedure
including extraction, clean-up, identification and quantification including all the relevant reagents and materials
3.1.12
operational performance characteristics
influence of the physical and chemical environment and maintenance problems, for example, mains voltage,
temperature, supply of certain substances, set-up time, period of unattended operation
3.1.13
pattern
chromatographic fingerprint of any series of PCB isomers
3.1.14
profile
graphic representation of the sums of the isomer concentrations of the PCBs
3.1.15
spiking
addition of C -labelled PCB standards of which the recovery is calculated and used to correct values of
native analytes of interest
3.1.16
statistical performance characteristics
quantification, for measured values, of the possible deviations resulting from the random part of the measuring
process, e.g. repeatability or instability
3.1.17
toxic equivalent factor
TEF
relative toxicity to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)
3.1.18
toxic equivalent quantity
TEQ
sum of toxic equivalents of each individual congener
3.2 Abbreviated terms
CRM certified reference material
GC/MS gas chromatography/mass spectrometry
GPC gel permeation chromatography
HPLC high-performance liquid chromatography
HRGC high-resolution gas chromatography
HRMS high-resolution mass spectrometry
IPR initial precision and recovery
LRMS low-resolution mass spectrometry
MDL method detection limit
ML minimum level (see Table 2)
PAR precision and recovery
PCB polychlorinated biphenyl
PCDD/PCDF polychlorinated dibenzo-p-dioxin/dibenzofuran
PCN polychlorinated naphthalene
PFK perfluorokerosene
SIM selected ion monitoring
SPE solid-phase extraction
TEF toxic equivalent factor
TEQ toxic equivalent quantity
VER calibration verification standard
4 Principle
4.1 Spiking and extraction
Stable isotopically labelled analogues of dioxin-like PCBs (diluted in a suitable solvent such as acetone) are
spiked into a 1 litre aqueous sample (a sample containing less than 1 % suspended solids). A minimum of one
labelled standard per homologue group is used and the sample is extracted by one of three procedures noted
in 4.1 a), 4.1 b) and 4.1 c). If the sample contains more than 1 % solid material, the solid portion can be
analysed directly after filtration or drying and the aqueous portion can be discarded.
a) Samples containing no visible particles are extracted with dichloromethane [6.4 f)] in a separatory funnel
or by solid-phase extraction. The extract is concentrated for clean-up.
b) Samples containing visible particles are vacuum filtered through a glass-fibre filter. The filter is extracted
in a Soxhlet extractor using toluene and the filtrate is extracted with dichloromethane [6.4 f)] in a
separatory funnel. The dichloromethane extract is concentrated and combined with the Soxhlet extract
prior to clean-up.
c) The sample is vacuum filtered through a glass-fibre filter on top of a solid-phase extraction (SPE) disk.
The filter and disk are eluted with suitable solvent mixtures or extracted in a Soxhlet or pressure filtration
extractor, and the extract is concentrated for clean-up.
Other solvents and extraction techniques may be substituted, provided that all the performance criteria can be
met.
4.2 Clean-up
After extraction, sample extracts are cleaned to remove interfering components. Sample clean-up procedures
1)
can include washes with acid and/or base, gel permeation, alumina, silica, Florisil and activated carbon
chromatography. High-performance liquid chromatography (HPLC) can be used for further isolation of other
specific co-planar compounds if required. Due to the large number of potential interfering compounds, sample
extracts shall be fractioned or analysed on at least two distinct GC column phases to ensure unique
identification and accurate quantification of each dioxin-like PCB congener.
4.3 Concentration
After clean-up, the extract(s) is concentrated to near dryness. Prior to injection, recovery standards are added
to each extract, and an aliquot of the extract is injected into the gas chromatograph. The analytes are
separated by GC and detected by a high-resolution mass spectrometer. Two exact masses are monitored for
each analyte.
1) Florisil 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 2007 – All rights reserved

Resolution greater than or equal to 10 000 is recommended. High-resolution gas chromatography/high-
resolution mass spectrometry at a resolution greater than or equal to 10 000 is at present required to achieve
adequate sensitivity and selectivity, and to allow the use of all C -labelled standards. If the sample extract
is being analysed for multi-component analyte groups (PCDD/Fs, PCBs, PCNs), a resolution of 10 000 is
necessary. At resolutions less than 10 000, some C PCDFs and PCBs interfere with native PCDDs of the
same level of chlorination. Resolutions less than 10 000 can be used for specific analyte groups (PCBs,
PCNs) where the matrix and potential interferences are well characterized.
4.4 Identification
An individual dioxin-like PCB is identified by comparing the GC retention time and ion abundance ratio of two
exact masses monitored (see Table 7) with the corresponding retention time of an authentic internal standard
and the theoretical or acquired ion-abundance ratio of the two exact masses. The isomers and congeners for
which there are no labelled analogues are identified when retention times or relative retention times and
ion-abundance ratios agree within predefined limits. Masses of those PCBs with a degree of chlorination
higher than three (e.g. PentaCB 110 for TetraCB 77) shall be monitored to ensure there is no contribution to
the mass of interest.
4.5 Quantification
Quantitative analysis is performed using selected ion monitoring (SIM) areas, in one of two ways.
a) For the dioxin-like PCBs for which labelled analogues have been added to the sample (4.1), the GC/MS
system is calibrated, and the concentration of each compound is determined using the isotope dilution
technique.
b) For the dioxin-like PCBs for which labelled analogues are not added, the GC/MS system is calibrated for
each compound using an isomer or congener with the most similar structure and the concentration of
each compound is determined using the internal standard technique.
4.6 Analytical quality
The quality of the analysis is assured through reproducible calibration and testing of the extraction, clean-up,
and GC/MS systems. Interferences, biases and limitations should be determined and identified for each target
analyte through intercalibration (interlaboratory) studies, certified reference materials (CRM) and spiked matrix
samples (SMS). A series of quality control (QC) samples (CRM, SMS) should be analysed with each set of
samples and monitored through control charting or other quality review procedures.
5 Contamination and interferences
5.1 Where possible, monitor or clean reagents by extraction or solvent rinse.
Solvents, reagents, labware, and other sample processing hardware can yield artefacts and/or elevated
baselines causing misinterpretation of chromatograms. (Example chromatograms showing typical retention
times of native and labelled PCBs are given in Annex A.) Specific selection of reagents and purification of
solvents by distillation in all-glass systems can be required. Many reagents, solvents and labware contain
background levels of dioxin-like compounds, e.g. PCB118 and PCB105.
5.2 Clean labware such that the method blank requirements given in 9.5.3 are met. An example of a
cleaning procedure is given below in a) to c).
a) Disassemble labware with removable parts, particularly separatory funnels with fluoropolymer stopcocks,
prior to detergent washing. Rinse labware with solvent and wash with a detergent solution as soon after
use as is practical. Sonication of labware containing a detergent solution for approximately 30 s can aid in
cleaning.
b) After detergent washing, rinse labware immediately with hot tap water. The tap water rinse shall be
followed by an acetone rinse, then a dichloromethane [6.4 f)] rinse/soak. For known contaminated
labware, use toluene as a final rinse/soak.
c) SoxhIet apparatus should be cycled with toluene for at least 20 cycles. Shake separatory funnels with
dichloromethane [6.4 f)] and/or toluene for 2 min, drain, and then shake with pure dichloromethane [6.4 f)]
for 2 min.
Proper cleaning of labware is extremely important because labware can contaminate the samples but can also
remove the analytes of interest by surface adsorption if the surface is activated during the cleaning procedure.
Glassware can be checked for contamination by analysing solvent rinses.
5.3 Demonstrate that all materials used in the analysis are free from interferences by running reference
matrix method blanks initially and with each sample batch (samples started through the extraction process on
a given 12-h shift, to a maximum of 20 samples); see 9.5, 15.5.
5.4 The reference matrix shall simulate, as closely as possible, the sample matrix under test. Ideally, the
reference matrix shall not contain dioxin-like compounds in detectable amounts, but shall contain potential
interferants in the concentrations expected to be found in the samples to be analysed.
Interferences co-extracted from samples can vary considerably from source to source, depending on the
diversity of the site being sampled. Interfering compounds, including PCBs of higher degrees of chlorination
can be present at concentrations several orders of magnitude higher than the dioxin-like PCBs being analysed.
The most frequently encountered interferences are dibenzo-p-dioxins, dibenzofurans, diphenyl ethers,
methoxy biphenyls, hydroxydiphenyl ethers, benzylphenyl ethers, aromatic sulfur compounds, polynuclear
aromatics, and pesticides. Because very low levels of dioxin-like PCBs are measured by this method, the
elimination of interferences is essential. The example clean-ups given in Clause 13 can be used to reduce or
eliminate these interferences and thereby permit reliable determination of the dioxin-like PCBs at the levels
shown in Table 2.
5.5 When a clean reference matrix that simulates the sample matrix under test is not available, use reagent
water (6.7) or a matrix that most closely resembles the sample.
5.6 Number each piece of reusable labware or minimally identify each set of specific type of labware (e.g.
Soxhlet extractors, round-bottom flasks) to associate that specific labware with the processing of a particular
sample or set of samples. This will assist the laboratory in tracking possible sources of contamination for
individual samples, identifying labware associated with highly contaminated samples that may require extra
cleaning, and determining when labware shall be discarded.
6 Reagents and standards
Use only reagents of recognized analytical grade, unless otherwise specified.
6.1 Water, complying with grade 3 as defined in ISO 3696.
6.2 pH adjustment and back-extraction reagents.
6.2.1 Potassium hydroxide solution.
Dissolve 20 g of potassium hydroxide, KOH, in 100 ml of water.
6.2.2 Sulfuric acid, H SO , ρ = 1,84 g/ml.
2 4
6.2.3 1 mol/l sulfuric acid.
Dilute with care 56 ml of concentrated sulfuric acid (6.2.2) to 1 litre of water (6.1).
6.2.4 Sodium chloride solution.
Dissolve 5 g of sodium chloride, NaCl, in 100 ml of water.
6.2.5 Sodium thiosulfate, Na S O .
2 2 3
6 © ISO 2007 – All rights reserved

6.3 Solution drying and evaporation reagents.
6.3.1 Sodium sulfate, Na SO , granular, anhydrous.
2 4
Bake at 300 °C for at least 24 h, cool in a desiccator, and store in a precleaned glass bottle with a screw cap
that prevents moisture from entering.
If, after heating, the sodium sulfate develops a noticeable greyish cast (due to the presence of carbon in the
crystal matrix), discard that batch of reagent as it is not suitable for use. Rinse with about 20 ml of
dichloromethane [6.4 f)] per gram of Na SO or extract with dichloromethane [6.4 f)] if background
2 4
contamination is detected.
6.3.2 Prepurified nitrogen, N 99,999 %.
6.4 Solvents for extraction and clean-up.
The extraction and clean-up solvents, distilled in glass, of pesticide quality and free of interferences, include
the following:
a) Acetone, C H O.
3 6
b) Toluene, C H .
7 8
c) Cyclohexane, C H .
6 12
d) Hexane, C H .
6 14
e) Methanol, CH OH.
f) Dichloromethane, CH Cl .
2 2
g) Diethyl ether, C H O.
4 10
h) Ethanol, C H O.
2 6
i) Nonane, C H .
9 20
6.5 GPC calibration solution.
Dissolve 300 mg/ml of corn oil, 15 mg/ml of bis(2-ethylhexyl) phthalate, C H O, 1,4 mg/ml of
24 38 4
pentachlorophenol, C Cl OH, 0,1 mg/ml of perylene, C H , and 0,5 mg/ml of sulfur, S, in dichloromethane
6 5 20 12
[6.4 f)]. Store in glass and keep refrigerated. Prepare fresh monthly.
6.6 Adsorbents for sample clean-up.
6.6.1 Silica, 70 µm to 230 µm.
6.6.1.1 Activated silica, baked at 180 °C for a minimum of 1 h, cooled in a desiccator, and stored in a
precleaned glass bottle with a screw cap that prevents moisture from entering. Prepare fresh every two weeks.
6.6.1.2 Acid silica, 30 % mass fraction.
Thoroughly mix 44,0 g of sulfuric acid (6.2.2) with 100 g of activated silica in a clean container. Break up
aggregates with a stirring rod until a uniform mixture is obtained. Store in a bottle with a fluoropolymer-lined
screw cap. 22 % acid silica and 44 % acid silica are prepared in a similar manner by adding 29 g and 80 g of
sulfuric acid, respectively, to 100 g of activated silica. Prepare fresh every two weeks.
6.6.1.3 Basic silica.
Thoroughly mix 30 g of 1 mol/l sodium hydroxide solution [c(NAOH) = 1 mol/l] with 100 g of activated silica in
a clean container. Break up aggregates with a stirring rod until a uniform mixture is obtained. Store in a bottle
with a fluoropolymer-lined screw cap. Prepare fresh every two weeks.
6.6.1.4 Potassium silicate, 36 % mass fraction.
Dissolve 56 g of high purity potassium hydroxide (6.2.1) in 300 ml of methanol [6.4 e)] in a 750 ml to 1 000 ml
flat-bottom flask. Add 100 g of silica (6.6.1) and a stirring bar, and stir on a hotplate at 60 °C to 70 °C for 1 h to
2 h. Decant the liquid and rinse the potassium silicate twice with 100 ml portions of methanol, followed by a
single rinse with 100 ml of dichloromethane [6.4 f)]. Spread the potassium silicate on solvent-rinsed aluminium
foil and dry for 2 h to 4 h in a hood. Activate overnight at 200 °C to 250 °C. Store in a bottle with a
fluoropolymer-lined screw cap. Prepare fresh every two weeks.
6.6.2 Alumina.
6.6.2.1 One of two types of alumina, acid or basic, can be used in the clean-up of sample extracts,
provided that the laboratory can meet the performance specifications for the recovery of labelled compounds
described in 9.4. The same type of alumina shall be used for all samples, including those used to demonstrate
initial precision and recovery (9.2).
a) Acid alumina, activate by heating to 130 °C for a minimum of 12 h.
b) Basic alumina, activate by heating to 600 °C for a minimum of 24 h.
6.6.2.2 Alternatively, activate by heating in a tube furnace at 650 °C to 700 °C under an airflow rate of
approximately 400 ml/min. Do not heat over 700 °C, as this can lead to reduced capacity for retaining the
analytes. Store at 130 °C in a covered flask. Use within 5 d of baking.
2)
ICN Alumina Super I or an equivalent may be used without activation.
6.6.3 Activated carbon.
3)
6.6.3.1 Mixture of carbon and silica, for example, Carbopak C (e.g. Supelco 1-0258, or equivalent)
4)
and Celite 545 (e.g. Supelco 2-0199, or equivalent).
Thoroughly mix 9,0 g of Carbopak C and 41,0 g of Celite 545 to produce a mass fraction of 18 % of the
mixture. Activate the mixture at 130 °C for at least 6 h. Store in a desiccator. Prepare fresh every two weeks.
5)
NOTE Active carbon-impregnated silica (Wako Pure Chemical Industries 019-11941) and active carbon-dispersed
6)
silica gel (Kanto Chemical Co. 01875-43) are examples of alternative materials.
7)
6.6.3.2 Carbon, e.g. Amoco PX21 .
Thoroughly mix 0,30 g of PX21 with 5,7 g of activated silica (6.6.1.1) in a vial. Cap and shake the vial for at
least 2 min or until mixture is homogeneous. Remove cap and place vial in oven at 300 °C for at least 60 h.
Store in a desiccator.
2) ICN Alumina Super I 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.
3) Carbopak C 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) Celite 545 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.
5) Active carbon-impregnated silica (019-11941) from Wako Pure Chemical Industries 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.
6) Active carbon-dispersed silica gel (01875-43) from Kanto Chemical Company 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.
7) Amoco PX21 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.
8 © ISO 2007 – All rights reserved

6.6.4 Florisil, 70 µm to 250 µm.
Activate in an oven above 130 °C for a minimum of 24 h. Use as soon as possible after removal from oven.
Activity of Florisil can be dependant on relative humidity. Prepare fresh for each use.
6.6.5 Silver nitrate/silica, (10 % mass fraction) for elimination of organosulfur and organohalogen
compounds, made of silver nitrate (AgNO ) of AR (Analytical Reagent) grade or equivalent and silica (6.6.1).
Dissolve 10 g of silver nitrate in 40 ml of water, add in portions 90 g of silica and shake until the mixture is
homogeneous. Let stand for 30 min. Transfer the mixture to a drying oven preheated to 70 °C and heat from
70 °C to 125 °C over a 2 h period. Activate at 125 °C for at least 10 h. Store the mixture in a brown glass
bottle. Prepare fresh for each use.
6.7 Reference matrices.
Reference matrices are matrices in which the dioxin-like PCBs and interfering compounds are not detected by
this method, e.g. reagent water, bottled water purchased locally, HPLC grade water or water prepared by
passage through activated carbon.
6.8 Standard solutions.
Purchase standard solutions as final working/calibration solutions or mixtures with certification indicating their
purity, concentration, and authenticity. Alternatively, prepare solutions from materials of known purity and
composition.
If the chemical purity is 98 % or greater, it is not necessary to correct the mass during the computation of the
concentration of analytes in the standard.
When not being used, store standards in the dark in sealed ampoules or screw-capped vials with
fluoropolymer-lined caps. Check the concentrations regularly so that solvent loss by evaporation can be
detected. If solvent loss has occurred, replace the solution.
Standard preparation (6.8 to 6.16) and Tables 2, 3 and 4 give examples of a standard scheme that is
acceptable. Other concentrations and spiking schemes may be used provided the performance criteria of the
method can be met (see also 4.1).
Observe the safety precautions in the warning note. Check stock standard solutions for signs o
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