SIST ISO 21675:2019

Water quality - Determination of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water - Method using solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS)

This document specifies a method for the determination of selected perfluoroalkyl and polyfluoroalkyl substances (PFAS) in non-filtrated waters, for example drinking water, natural water (fresh water and sea water) and waste water containing less than 2 g/l solid particulate material (SPM) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The compounds monitored by this method are typically the linear isomers. The group of compounds determined by this method are representative of a wide variety of PFAS. The analytes specified in Table 1 can be determined by this method. The list can be modified depending on the purpose for which the method is intended. The lower application range of this method can vary depending on the sensitivity of the equipment used and the matrix of the sample. For most compounds to which this document applies ≥0,2 ng/l as limit of quantification can be achieved. Actual levels can depend on the blank levels realized by individual laboratory. The applicability of the method to further substances, not listed in Table 1, or to further types of water is not excluded, but is intended to be validated separately for each individual case.

Qualité de l'eau - Détermination des substances d'alkyle perfluorés et polyfluorés (SPFA) dans l'eau - Méthode par extraction en phase solide et chromatographie liquide et spectrométrie de masse en tandem (CL-SM/SM)

Kakovost vode - Določevanje perfluoroalkil in polifluoroalkil spojin (PFAS) v vodi - Metoda z ekstrakcijo na trdni fazi in s tekočinsko kromatografijo-tandemsko masno spektrometrijo (LC-MS/MS)

Ta dokument določa metodo za določevanje izbranih perfluoroalkilnih in polifluoroalkilnih spojin (PFAS) v nefiltrirani vodi, na primer pitni vodi, naravni vodi (sladka in morska voda) ter odpadni vodi, ki vsebuje manj kot 2 g/l trdnih delcev (SPM) z uporabo tekočinske kromatografije-tandemske masne spektrometrije (LC-MS/MS). Spojine, ki jih nadzira ta metoda, so običajno linearni izomeri. Skupine spojin, določene s to metodo, so reprezentativne za najrazličnejše spojine PFAS. S to metodo je mogoče določiti analite, opredeljene v preglednici 1. Seznam je mogoče spremeniti glede na namen, za katerega je metoda namenjena. Spodnje področje uporabe te metode se lahko razlikuje glede na občutljivost uporabljene opreme in matrico vzorca. Za večino spojin, za katere se uporablja ta dokument, je mogoče doseči mejo količinskega določanja ≥ 0,2 ng/l. Dejanske ravni so lahko odvisne od slepih ravni, ki jih doseže posamezen laboratorij. Uporabnost metode za druge spojine, ki niso navedene v preglednici 1, ali za druge vrste vode ni izključena, vendar naj bi jo posebej potrdili za vsak posamezen primer.

General Information

• Status: Published
• Public Enquiry End Date: 03-Nov-2019
• Publication Date: 10-Nov-2019
• ICS: 13.060.50 - Examination of water for chemical substances
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: KAV - Water quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 04-Nov-2019
• Due Date: 09-Jan-2020
• Completion Date: 11-Nov-2019
• Ref Project: ISO 21675:2019 - Water quality — Determination of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in water — Method using solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 21675
First edition
2019-10
Water quality — Determination of
perfluoroalkyl and polyfluoroalkyl
substances (PFAS) in water — Method
using solid phase extraction and
liquid chromatography-tandem mass
spectrometry (LC-MS/MS)
Qualité de l'eau — Détermination des substances d'alkyle perfluorés
et polyfluorés (SPFA) dans l'eau — Méthode par extraction en phase
solide et chromatographie liquide et spectrométrie de masse en
tandem (CL-SM/SM)
Reference number
ISO 21675:2019(E)
©
ISO 2019

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ISO 21675:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
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Published in Switzerland
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ISO 21675:2019(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Interferences . 3
5.1 Interferences with sampling and extraction . 3
5.2 Interferences with LC-MS/MS. 4
6 Reagents . 4
7 Apparatus . 7
8 Sampling . 8
9 Procedure. 8
9.1 Solid-phase extraction . 8
9.1.1 General. 8
9.1.2 Sample preparation . 8
9.1.3 Conditioning of the solid-phase extraction material . 9
9.1.4 Sample extraction . 9
9.1.5 Elution . 9
9.2 LC-MS/MS operating conditions .10
9.3 Blank determination .12
9.4 Identification .12
10 Calibration .13
10.1 General requirements .13
10.2 Calibration using an external standard .13
10.3 Calibration using an internal standard .14
11 Calculation .15
11.1 Use of a calibration curve to determine concentration .15
11.2 Calculation of concentration using calibration with external standards .15
11.3 Calculation of concentration using calibration with internal standards .16
11.4 Treatment of results outside the calibration range .16
12 Determination of analyte recovery .16
12.1 Recovery .16
12.2 Recovery of internal standards .17
13 Expression of results .18
14 Test report .18
Annex A (informative) Examples of suitable sorbents .19
Annex B (informative) Examples of suitable LC columns .20
Annex C (informative) Examples of suitable LC-MS/MS conditions .21
Annex D (normative) Filtration and extraction of suspended matter in the sample .25
Annex E (informative) Examples of chromatographic separation of individual linear and
branched PFAS isomers .27
Annex F (informative) Rapid method by direct injection .31
Annex G (informative) Rapid method by online solid phase extraction LC-MS/MS .32
Annex H (informative) Performance data by DIN 38407-42 for selected PFAS .35
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ISO 21675:2019(E)

Annex I (informative) Performance data .37
Bibliography .43
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ISO 21675:2019(E)

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
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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).
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expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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INTERNATIONAL STANDARD ISO 21675:2019(E)
Water quality — Determination of perfluoroalkyl and
polyfluoroalkyl substances (PFAS) in water — Method
using solid phase extraction and liquid chromatography-
tandem mass spectrometry (LC-MS/MS)
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document 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.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document
be carried out by suitably qualified staff.
1 Scope
This document specifies a method for the determination of selected perfluoroalkyl and polyfluoroalkyl
substances (PFAS) in non-filtrated waters, for example drinking water, natural water (fresh water and
sea water) and waste water containing less than 2 g/l solid particulate material (SPM) using liquid
chromatography-tandem mass spectrometry (LC-MS/MS). The compounds monitored by this method
are typically the linear isomers. The group of compounds determined by this method are representative
of a wide variety of PFAS. The analytes specified in Table 1 can be determined by this method. The list
can be modified depending on the purpose for which the method is intended. The lower application
range of this method can vary depending on the sensitivity of the equipment used and the matrix of the
sample. For most compounds to which this document applies ≥0,2 ng/l as limit of quantification can be
achieved. Actual levels can depend on the blank levels realized by individual laboratory.
The applicability of the method to further substances, not listed in Table 1, or to further types of water
is not excluded, but is intended to be validated separately for each individual case.
NOTE 1 PFAS is used in this document to describe the analytes monitored. Many of the compounds in Table 1
are perfluoroalkyl and are also considered polyfluoroalkyl substances.
NOTE 2 The linear PFAS isomers are specified in this document. The branched isomers can be present in
environmental samples, especially for PFOS. Annex E provides an example of an analytical approach to the
chromatographic and spectroscopic separation of individual isomers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 21253-1, Water quality — Multi-compound class methods — Part 1: Criteria for the identification of
target compounds by gas and liquid chromatography and mass spectrometry
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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ISO 21675:2019(E)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org ./ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
perfluoroalkyl and polyfluoroalkyl substances
PFAS
commonly used international abbreviation for organic compounds with replacement of most or all
hydrogen atoms by fluorine in the aliphatic chain structure
Note 1 to entry: The term is used in the broader sense for per- and polyfluoroalkyl substances (PFAS), and per-
and polyfluorinated compounds (PFC) as well.
4 Principle
The analytes listed in Table 1 are extracted from the water sample by solid-phase extraction
using a weak anion exchange sorbent followed by solvent elution and determination by liquid
chromatography-tandem mass-spectrometry.
The user should be aware that each analyte has its own specific optimum conditions and therefore
modification of the analyte list could require the specification of additional conditions for each
additional parameter.
Table 1 — Analytes determinable by this method
a b
Analyte IUPAC name Formula Abbreviation CAS-RN
Perfluoro-n- 1,1,2,2,3,3,4,4,4-Nonafluorobutane-1-sul- C HF O S PFBS 375-73-5
4 9 3
butanesulfonic acid fonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,6-Tridecafluorohex- C HF O S PFHxS 355-46-4
6 13 3
hexanesulfonic acid ane-1-sulfonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7-Pentade- C HF O S PFHpS 375-92-8
7 15 3
heptanesulfonic acid cafluoroheptane-1-sulfonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Heptade- C HF O S PFOS 1763-23-1
8 17 3
octanesulfonic acid cafluorooctane-1-sulfonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Hen- C HF O S PFDS 335-77-3
10 21 3
decanesulfonic acid icosafluorodecane-1-sulfonic acid
Perfluorooctanesulfo- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Heptade- C H F NO S FOSA 754-91-6
8 2 17 2
namide cafluoro-1-octanesulfonamide
N-methyl 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Heptade- C H F NO S N-MeFOSA 31506-32-8
9 4 17 2
perfluorooctanesulfo- cafluoro-N-methyl-1-octanesulfonamide
namide
N-ethyl N-Ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-he C H F NO S N-EtFOSA 4151-50-2
10 6 17 2
perfluorooctanesulfo- ptadecafluorooctane-1-sulfonamide
namide
N-methyl 2-[1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Hepta- C H F NO S N-MeFOSAA 2355-31-9
11 6 17 4
perfluorooctanesulfon- decafluorooctylsulfonyl(methyl)amino]
amidoacetic acid acetic acid
N-ethyl 2-[Ethyl(1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8 C H F NO S N-EtFOSAA 2991-50-6
12 8 17 4
perfluorooctanesulfon- -heptadecafluorooctylsulfonyl)amino]
amidoacetic acid acetic acid
6:2 Fluorotelomer sul- 3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluorooc- C H F O S 6:2 FTSA 27619-97-2
8 5 13 3
fonic acid tane-1-sulfonic acid
8:2 Fluorotelomer sul- 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Heptade- C H F O S 8:2 FTSA 39108-34-4
10 5 17 3
fonic acid cafluorodecane-1-sulfonic acid
a
IUPAC: International Union of Pure and Applied Chemistry.
b
CAS-RN: Chemical Abstract Services Registry Number.
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ISO 21675:2019(E)

Table 1 (continued)
a b
Analyte IUPAC name Formula Abbreviation CAS-RN
9-Chlorohexade- 2-(6-Chloro-1,1,2,2,3,3,4,4,5,5,6,6-do- C HClF O S 9Cl-PF3ONS 73606-19-6
8 16 4
cafluoro-3-oxanon- decafluorohexoxy)-1,1,2,2-tetrafluo-
ane-1-sulfonic acid roethanesulfonic acid
Perfluoro-n-butanoic 2,2,3,3,4,4,4-Heptafluorobutanoic acid C HF O PFBA 375-22-4
4 7 2
acid
Perfluoro-n- 2,2,3,3,4,4,5,5,5-Nonafluoropentanoic acid C HF O PFPeA 2706-90-3
5 9 2
pentanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,6-Undecafluorohexa- C HF O PFHxA 307-24-4
6 11 2
hexanoic acid noic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,7-Tridecafluorohep- C HF O PFHpA 375-85-9
7 13 2
heptanoic acid tanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluo- C HF O PFOA 335-67-1
8 15 2
octanoic acid rooctanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-Heptade- C HF O PFNA 375-95-1
9 17 2
nonanoic acid cafluorononanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Non- C HF O PFDA 335-76-2
10 19 2
decanoic acid adecafluorodecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFUnDA 2058-94-8
11 21 2
undecanoic acid 11,11,11-Henicosafluoroundecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFDoDA 307-55-1
12 23 2
dodecanoic acid 11,11,12,12,12-Tricosafluorododecanoic
acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFTrDA 72629-94-8
13 25 2
tridecanoic acid 11,11,12,12,13,13,13-Pentacosafluorotri-
decanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFTeDA 376-06-7
14 27 2
tetradecanoic acid 11,11,12,12,13,13,14,14,14-Hepta-
cosafluorotetradecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFHxDA 67905-19-5
16 31 2
hexadecanoic acid 11,11,12,12,13,13,14,14,15,15,16,16,
16-Hentriacontafluorohexadecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFOcDA 16517-11-6
18 35 2
octadecanoic acid 11,11,12,12,13,13,14,14,15,15,16,16,
17,17,18,18,18-Pentatriacontafluoroocta-
decanoic acid
8:2 Fluorotelomer 3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Hexade- C H F O 8:2 FTUCA 70887-84-2
10 2 16 2
unsaturated carboxylic cafluorodec-2-enoic acid
acid
8:2 Polyfluoroalkyl Bis(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-he C H F O P 8:2 diPAP 678-41-1
20 9 34 4
phosphate diester ptadecafluorodecyl) hydrogen phosphate
Hexafluoropropylene 2,3,3,3-Tetrafluoro-2-(1,1,2,2,3,3,3- C HF O HFPO-DA 13252-13-6
6 11 3
oxide dimer acid heptafluoropropoxy)propanoic acid
4,8-Dioxa-3H-perfluor- 2,2,3-Trifluoro-3-[1,1,2,2,3,3-hex- C H F O DONA 919005-14-4
7 2 12 4
ononanoic acid afluoro-3-(trifluoromethoxy)propoxy]
propanoic acid
a
IUPAC: International Union of Pure and Applied Chemistry.
b
CAS-RN: Chemical Abstract Services Registry Number.
5 Interferences
5.1 Interferences with sampling and extraction
Sample bottles (7.1) shall consist of materials that do not contaminate or change the composition of the
sample during sample storage. All types of fluoropolymer plastics, including polytetrafluoroethylene
(PTFE) and fluoroelastomer materials, shall be avoided during sampling, sample storage and extraction.
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ISO 21675:2019(E)

Sample bottles (7.1) shall be checked for possible background contamination before use. If background
contamination is suspected or detected in sample bottles (7.1), then wash sample bottles (7.1) with
water (6.1) and methanol (6.6) prior to use. To avoid cross contamination, the sample bottles (7.1) should
only be used once. The use of intermediate sample tubes (7.6) and vials (7.10) should be limited in the
overall process to avoid contamination of loss by sorption. To avoid losses resulting from adsorption of
target analytes to the wall of sample bottle (7.1) and reservoir column (7.4), extract all of the sample
from the sample bottle (7.1) and rinse the wall of sample bottle (7.1) and reservoir column (7.4) with
methanol (6.6).
Commercially available adsorbent materials often vary in quality or activity. Considerable batch-
to-batch differences in quality and selectivity of these materials are possible. The recovery of a
single substance may also vary with respect to its concentration. Therefore, check analyte recovery
periodically at different concentrations and whenever new batches/lots of reagents or labware are
used (12.1).
5.2 Interferences with LC-MS/MS
Substances with similar retention times that can produce ions with similar mass to charge ratios (m/z)
to those produced by the analytes of interest may interfere with the determination.
These interferences may lead to incompletely resolved signals and/or additional signals in the mass
chromatograms of target substances. Depending on their levels in the sample, such substances may
affect the accuracy and precision of the results. The chromatographic separation is different with the
LC column (see Annex C for examples). As long as the peak of interest can be separately integrated from
interferences, it may be used.
Matrix interferences may be caused by contaminants that are co-extracted from the samples. The extent
of matrix interferences varies considerably, depending on the nature of the samples. In drinking water
and ground water, matrix interferences are usually negligible, whereas waste water and sea water
matrices can be affected by matrix interferences that lead to ionization suppression or enhancement
resulting in bias or reduced sensitivity of the method. As long as the required limits of quantification
can be achieved in samples, samples can be diluted to minimize matrix effects.
Interferences arising directly from analytical instruments can be significant for unmodified commercial
LC systems because many parts are made of PTFE and other fluoropolymers. It is necessary to check
for possible blank contamination from the individual parts, such as tubing, solvent inlet filters, valve
seals and the degassing equipment, and replace these with materials such as stainless steel and
polyetheretherketone (PEEK), where possible.
NOTE Background contamination can arise from within the instrument. A delay column can be attached
between the solvent mixer and injection valve to chromatographically resolve these background contaminants
from the instrument and/or mobile phases from the target analytes.
The LC-vial caps shall be free of fluoropolymer material. Efforts should be taken to minimize background
levels in procedural blank materials such that the procedural blank, including the instrumental blank,
is at least 10-fold below the reporting limit.
6 Reagents
Whenever possible, use certified or analytical-grade reagents or residue free-analytical grade
reagents stored in glass or polypropylene containers with metal or polypropylene lined caps. Avoid
using reagents with fluoropolymer lined caps and check contamination levels of target substances
using repeated blank determinations. Carry out additional cleaning or conditioning steps to ensure
background levels are minimized, if necessary.
6.1 Water, blank-value free, e.g. complying with grade 1 as specified in ISO 3696.
Purified laboratory water can be used, but should be confirmed to be free of PFAS. The quality of water
is checked by the same procedure given in 9.3.
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ISO 21675:2019(E)

6.2 Acetic acid, w(CH COOH) = 99,9 % mass fraction (999 g/kg).
3
6.3 Acetonitrile, CH CN.
3
6.4 Ammonia solution, w(NH ) = 25 % mass fraction (250 g/kg).
3
6.5 Ammonium acetate, w(CH COONH ) = 97 % mass fraction (970 g/kg).
3 4
6.6 Methanol, CH OH, blank-value free.
3
NOTE The quality of methanol is checked by evaporating 10 ml of methanol with a gentle stream of nitrogen
gas (6.13) to 0,5 ml and determining levels according to this document.
6.7 Reference substances, see Table 1.
Reference substances are analytical standards used for quantitative determination of the method
analytes. Use only reference substances or solutions, where the content of linear isomers is at least
95 %. Make sure that the individual reference substances do not contain detectable concentrations of
other target analytes to be determined by analysing alternate lots or second sources.
NOTE Solutions of reference substances are commercially available.
6.8 Internal standard substances, see Table 3.
Internal standard substances are labelled forms of the reference substances to be used in the analytical
procedure to correct for recovery due to losses of analyte or changes in analytical conditions that could
result in bias. Make sure that the internal standard substances do not contain detectable concentrations
of the analytes to be determined by analysing new lots using this document.
NOTE Solutions of internal standard substances are commercially available.
6.9 Preparation of the solutions
Calculate the concentration of all reference substances and internal standard solutions with regard to
the anion content.
Store the solutions at (5 ± 3) °C in the dark, protected against evaporation. Bring them to room
temperature prior to use (i.e. before dilution or spiking or injection).
6.9.1 Individual stock solutions of the reference substances
Stock solutions of the individual reference substances (6.7) in methanol (6.6) or acetonitrile (6.3) should
be of mass concentration to enable dilution to the desired range, e.g. 50 μg/ml each.
6.9.2 Individual stock solutions of internal standard substances
Stock solutions of the individual internal standard substances (6.8) in methanol (6.6) or acetonitrile (6.3)
should be of mass concentration to enable dilution to the desired range, e.g. 50 μg/ml each.
6.9.3 Native stock solution (reference substances)
Prepare a solution of the reference substances with a mass concentration of, for example, 0,1 μg/ml each.
Fill, for example, 1 ml of each solution of the individual reference substances, for example 50 μg/ml
(6.9.1), into a 500 ml volumetric flask (7.7) and make the solution up to the mark with methanol (6.6).
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6.9.4 Labelled stock solution (internal standard substances)
Prepare a solution of the labelled internal standard substances with a mass concentration of, for
example, 0,1 μg/ml each.
Fill, for example, 1 ml of each solution of the individual internal standard substances, e.g. 50 μg/ml
(6.9.2), into a 500 ml volumetric flask (7.7) and make the solution up to the mark with methanol (6.6).
6.9.5 Spiking solution (reference substances)
Prepare a solution of the reference substances with a mass concentration of, for example, 10 ng/ml each.
Fill, for example, 1 ml of the native stock solution e.g. 0,1 μg/ml (6.9.3) into a 10 ml volumetric flask (7.7)
and make the solution up to the mark with methanol (6.6).
This solution is used for recovery samples (see 12.1).
6.9.6 Spiking solution (in
...

SLOVENSKI STANDARD
SIST ISO 21675:2019
01-december-2019
Kakovost vode - Določevanje perfluoroalkil in polifluoroalkil spojin (PFAS) v vodi -
Metoda z ekstrakcijo na trdni fazi in s tekočinsko kromatografijo-tandemsko
masno spektrometrijo (LC-MS/MS)
Water quality - Determination of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in
water - Method using solid phase extraction and liquid chromatography-tandem mass
spectrometry (LC-MS/MS)
Qualité de l'eau - Détermination des substances d'alkyle perfluorés et polyfluorés (SPFA)
dans l'eau - Méthode par extraction en phase solide et chromatographie liquide et
spectrométrie de masse en tandem (CL-SM/SM)
Ta slovenski standard je istoveten z: ISO 21675:2019
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
SIST ISO 21675:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 21675:2019

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SIST ISO 21675:2019
INTERNATIONAL ISO
STANDARD 21675
First edition
2019-10
Water quality — Determination of
perfluoroalkyl and polyfluoroalkyl
substances (PFAS) in water — Method
using solid phase extraction and
liquid chromatography-tandem mass
spectrometry (LC-MS/MS)
Qualité de l'eau — Détermination des substances d'alkyle perfluorés
et polyfluorés (SPFA) dans l'eau — Méthode par extraction en phase
solide et chromatographie liquide et spectrométrie de masse en
tandem (CL-SM/SM)
Reference number
ISO 21675:2019(E)
©
ISO 2019

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SIST ISO 21675:2019
ISO 21675:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
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Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

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SIST ISO 21675:2019
ISO 21675:2019(E)

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Interferences . 3
5.1 Interferences with sampling and extraction . 3
5.2 Interferences with LC-MS/MS. 4
6 Reagents . 4
7 Apparatus . 7
8 Sampling . 8
9 Procedure. 8
9.1 Solid-phase extraction . 8
9.1.1 General. 8
9.1.2 Sample preparation . 8
9.1.3 Conditioning of the solid-phase extraction material . 9
9.1.4 Sample extraction . 9
9.1.5 Elution . 9
9.2 LC-MS/MS operating conditions .10
9.3 Blank determination .12
9.4 Identification .12
10 Calibration .13
10.1 General requirements .13
10.2 Calibration using an external standard .13
10.3 Calibration using an internal standard .14
11 Calculation .15
11.1 Use of a calibration curve to determine concentration .15
11.2 Calculation of concentration using calibration with external standards .15
11.3 Calculation of concentration using calibration with internal standards .16
11.4 Treatment of results outside the calibration range .16
12 Determination of analyte recovery .16
12.1 Recovery .16
12.2 Recovery of internal standards .17
13 Expression of results .18
14 Test report .18
Annex A (informative) Examples of suitable sorbents .19
Annex B (informative) Examples of suitable LC columns .20
Annex C (informative) Examples of suitable LC-MS/MS conditions .21
Annex D (normative) Filtration and extraction of suspended matter in the sample .25
Annex E (informative) Examples of chromatographic separation of individual linear and
branched PFAS isomers .27
Annex F (informative) Rapid method by direct injection .31
Annex G (informative) Rapid method by online solid phase extraction LC-MS/MS .32
Annex H (informative) Performance data by DIN 38407-42 for selected PFAS .35
© ISO 2019 – All rights reserved iii

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ISO 21675:2019(E)

Annex I (informative) Performance data .37
Bibliography .43
iv © ISO 2019 – All rights reserved

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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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2019 – All rights reserved v

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SIST ISO 21675:2019

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SIST ISO 21675:2019
INTERNATIONAL STANDARD ISO 21675:2019(E)
Water quality — Determination of perfluoroalkyl and
polyfluoroalkyl substances (PFAS) in water — Method
using solid phase extraction and liquid chromatography-
tandem mass spectrometry (LC-MS/MS)
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document 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.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document
be carried out by suitably qualified staff.
1 Scope
This document specifies a method for the determination of selected perfluoroalkyl and polyfluoroalkyl
substances (PFAS) in non-filtrated waters, for example drinking water, natural water (fresh water and
sea water) and waste water containing less than 2 g/l solid particulate material (SPM) using liquid
chromatography-tandem mass spectrometry (LC-MS/MS). The compounds monitored by this method
are typically the linear isomers. The group of compounds determined by this method are representative
of a wide variety of PFAS. The analytes specified in Table 1 can be determined by this method. The list
can be modified depending on the purpose for which the method is intended. The lower application
range of this method can vary depending on the sensitivity of the equipment used and the matrix of the
sample. For most compounds to which this document applies ≥0,2 ng/l as limit of quantification can be
achieved. Actual levels can depend on the blank levels realized by individual laboratory.
The applicability of the method to further substances, not listed in Table 1, or to further types of water
is not excluded, but is intended to be validated separately for each individual case.
NOTE 1 PFAS is used in this document to describe the analytes monitored. Many of the compounds in Table 1
are perfluoroalkyl and are also considered polyfluoroalkyl substances.
NOTE 2 The linear PFAS isomers are specified in this document. The branched isomers can be present in
environmental samples, especially for PFOS. Annex E provides an example of an analytical approach to the
chromatographic and spectroscopic separation of individual isomers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 21253-1, Water quality — Multi-compound class methods — Part 1: Criteria for the identification of
target compounds by gas and liquid chromatography and mass spectrometry
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
© ISO 2019 – All rights reserved 1

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ISO 21675:2019(E)

ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org ./ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
perfluoroalkyl and polyfluoroalkyl substances
PFAS
commonly used international abbreviation for organic compounds with replacement of most or all
hydrogen atoms by fluorine in the aliphatic chain structure
Note 1 to entry: The term is used in the broader sense for per- and polyfluoroalkyl substances (PFAS), and per-
and polyfluorinated compounds (PFC) as well.
4 Principle
The analytes listed in Table 1 are extracted from the water sample by solid-phase extraction
using a weak anion exchange sorbent followed by solvent elution and determination by liquid
chromatography-tandem mass-spectrometry.
The user should be aware that each analyte has its own specific optimum conditions and therefore
modification of the analyte list could require the specification of additional conditions for each
additional parameter.
Table 1 — Analytes determinable by this method
a b
Analyte IUPAC name Formula Abbreviation CAS-RN
Perfluoro-n- 1,1,2,2,3,3,4,4,4-Nonafluorobutane-1-sul- C HF O S PFBS 375-73-5
4 9 3
butanesulfonic acid fonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,6-Tridecafluorohex- C HF O S PFHxS 355-46-4
6 13 3
hexanesulfonic acid ane-1-sulfonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7-Pentade- C HF O S PFHpS 375-92-8
7 15 3
heptanesulfonic acid cafluoroheptane-1-sulfonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Heptade- C HF O S PFOS 1763-23-1
8 17 3
octanesulfonic acid cafluorooctane-1-sulfonic acid
Perfluoro-n- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Hen- C HF O S PFDS 335-77-3
10 21 3
decanesulfonic acid icosafluorodecane-1-sulfonic acid
Perfluorooctanesulfo- 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Heptade- C H F NO S FOSA 754-91-6
8 2 17 2
namide cafluoro-1-octanesulfonamide
N-methyl 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Heptade- C H F NO S N-MeFOSA 31506-32-8
9 4 17 2
perfluorooctanesulfo- cafluoro-N-methyl-1-octanesulfonamide
namide
N-ethyl N-Ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-he C H F NO S N-EtFOSA 4151-50-2
10 6 17 2
perfluorooctanesulfo- ptadecafluorooctane-1-sulfonamide
namide
N-methyl 2-[1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Hepta- C H F NO S N-MeFOSAA 2355-31-9
11 6 17 4
perfluorooctanesulfon- decafluorooctylsulfonyl(methyl)amino]
amidoacetic acid acetic acid
N-ethyl 2-[Ethyl(1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8 C H F NO S N-EtFOSAA 2991-50-6
12 8 17 4
perfluorooctanesulfon- -heptadecafluorooctylsulfonyl)amino]
amidoacetic acid acetic acid
6:2 Fluorotelomer sul- 3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluorooc- C H F O S 6:2 FTSA 27619-97-2
8 5 13 3
fonic acid tane-1-sulfonic acid
8:2 Fluorotelomer sul- 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Heptade- C H F O S 8:2 FTSA 39108-34-4
10 5 17 3
fonic acid cafluorodecane-1-sulfonic acid
a
IUPAC: International Union of Pure and Applied Chemistry.
b
CAS-RN: Chemical Abstract Services Registry Number.
2 © ISO 2019 – All rights reserved

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SIST ISO 21675:2019
ISO 21675:2019(E)

Table 1 (continued)
a b
Analyte IUPAC name Formula Abbreviation CAS-RN
9-Chlorohexade- 2-(6-Chloro-1,1,2,2,3,3,4,4,5,5,6,6-do- C HClF O S 9Cl-PF3ONS 73606-19-6
8 16 4
cafluoro-3-oxanon- decafluorohexoxy)-1,1,2,2-tetrafluo-
ane-1-sulfonic acid roethanesulfonic acid
Perfluoro-n-butanoic 2,2,3,3,4,4,4-Heptafluorobutanoic acid C HF O PFBA 375-22-4
4 7 2
acid
Perfluoro-n- 2,2,3,3,4,4,5,5,5-Nonafluoropentanoic acid C HF O PFPeA 2706-90-3
5 9 2
pentanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,6-Undecafluorohexa- C HF O PFHxA 307-24-4
6 11 2
hexanoic acid noic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,7-Tridecafluorohep- C HF O PFHpA 375-85-9
7 13 2
heptanoic acid tanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluo- C HF O PFOA 335-67-1
8 15 2
octanoic acid rooctanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-Heptade- C HF O PFNA 375-95-1
9 17 2
nonanoic acid cafluorononanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Non- C HF O PFDA 335-76-2
10 19 2
decanoic acid adecafluorodecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFUnDA 2058-94-8
11 21 2
undecanoic acid 11,11,11-Henicosafluoroundecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFDoDA 307-55-1
12 23 2
dodecanoic acid 11,11,12,12,12-Tricosafluorododecanoic
acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFTrDA 72629-94-8
13 25 2
tridecanoic acid 11,11,12,12,13,13,13-Pentacosafluorotri-
decanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFTeDA 376-06-7
14 27 2
tetradecanoic acid 11,11,12,12,13,13,14,14,14-Hepta-
cosafluorotetradecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFHxDA 67905-19-5
16 31 2
hexadecanoic acid 11,11,12,12,13,13,14,14,15,15,16,16,
16-Hentriacontafluorohexadecanoic acid
Perfluoro-n- 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFOcDA 16517-11-6
18 35 2
octadecanoic acid 11,11,12,12,13,13,14,14,15,15,16,16,
17,17,18,18,18-Pentatriacontafluoroocta-
decanoic acid
8:2 Fluorotelomer 3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Hexade- C H F O 8:2 FTUCA 70887-84-2
10 2 16 2
unsaturated carboxylic cafluorodec-2-enoic acid
acid
8:2 Polyfluoroalkyl Bis(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-he C H F O P 8:2 diPAP 678-41-1
20 9 34 4
phosphate diester ptadecafluorodecyl) hydrogen phosphate
Hexafluoropropylene 2,3,3,3-Tetrafluoro-2-(1,1,2,2,3,3,3- C HF O HFPO-DA 13252-13-6
6 11 3
oxide dimer acid heptafluoropropoxy)propanoic acid
4,8-Dioxa-3H-perfluor- 2,2,3-Trifluoro-3-[1,1,2,2,3,3-hex- C H F O DONA 919005-14-4
7 2 12 4
ononanoic acid afluoro-3-(trifluoromethoxy)propoxy]
propanoic acid
a
IUPAC: International Union of Pure and Applied Chemistry.
b
CAS-RN: Chemical Abstract Services Registry Number.
5 Interferences
5.1 Interferences with sampling and extraction
Sample bottles (7.1) shall consist of materials that do not contaminate or change the composition of the
sample during sample storage. All types of fluoropolymer plastics, including polytetrafluoroethylene
(PTFE) and fluoroelastomer materials, shall be avoided during sampling, sample storage and extraction.
© ISO 2019 – All rights reserved 3

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ISO 21675:2019(E)

Sample bottles (7.1) shall be checked for possible background contamination before use. If background
contamination is suspected or detected in sample bottles (7.1), then wash sample bottles (7.1) with
water (6.1) and methanol (6.6) prior to use. To avoid cross contamination, the sample bottles (7.1) should
only be used once. The use of intermediate sample tubes (7.6) and vials (7.10) should be limited in the
overall process to avoid contamination of loss by sorption. To avoid losses resulting from adsorption of
target analytes to the wall of sample bottle (7.1) and reservoir column (7.4), extract all of the sample
from the sample bottle (7.1) and rinse the wall of sample bottle (7.1) and reservoir column (7.4) with
methanol (6.6).
Commercially available adsorbent materials often vary in quality or activity. Considerable batch-
to-batch differences in quality and selectivity of these materials are possible. The recovery of a
single substance may also vary with respect to its concentration. Therefore, check analyte recovery
periodically at different concentrations and whenever new batches/lots of reagents or labware are
used (12.1).
5.2 Interferences with LC-MS/MS
Substances with similar retention times that can produce ions with similar mass to charge ratios (m/z)
to those produced by the analytes of interest may interfere with the determination.
These interferences may lead to incompletely resolved signals and/or additional signals in the mass
chromatograms of target substances. Depending on their levels in the sample, such substances may
affect the accuracy and precision of the results. The chromatographic separation is different with the
LC column (see Annex C for examples). As long as the peak of interest can be separately integrated from
interferences, it may be used.
Matrix interferences may be caused by contaminants that are co-extracted from the samples. The extent
of matrix interferences varies considerably, depending on the nature of the samples. In drinking water
and ground water, matrix interferences are usually negligible, whereas waste water and sea water
matrices can be affected by matrix interferences that lead to ionization suppression or enhancement
resulting in bias or reduced sensitivity of the method. As long as the required limits of quantification
can be achieved in samples, samples can be diluted to minimize matrix effects.
Interferences arising directly from analytical instruments can be significant for unmodified commercial
LC systems because many parts are made of PTFE and other fluoropolymers. It is necessary to check
for possible blank contamination from the individual parts, such as tubing, solvent inlet filters, valve
seals and the degassing equipment, and replace these with materials such as stainless steel and
polyetheretherketone (PEEK), where possible.
NOTE Background contamination can arise from within the instrument. A delay column can be attached
between the solvent mixer and injection valve to chromatographically resolve these background contaminants
from the instrument and/or mobile phases from the target analytes.
The LC-vial caps shall be free of fluoropolymer material. Efforts should be taken to minimize background
levels in procedural blank materials such that the procedural blank, including the instrumental blank,
is at least 10-fold below the reporting limit.
6 Reagents
Whenever possible, use certified or analytical-grade reagents or residue free-analytical grade
reagents stored in glass or polypropylene containers with metal or polypropylene lined caps. Avoid
using reagents with fluoropolymer lined caps and check contamination levels of target substances
using repeated blank determinations. Carry out additional cleaning or conditioning steps to ensure
background levels are minimized, if necessary.
6.1 Water, blank-value free, e.g. complying with grade 1 as specified in ISO 3696.
Purified laboratory water can be used, but should be confirmed to be free of PFAS. The quality of water
is checked by the same procedure given in 9.3.
4 © ISO 2019 – All rights reserved

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ISO 21675:2019(E)

6.2 Acetic acid, w(CH COOH) = 99,9 % mass fraction (999 g/kg).
3
6.3 Acetonitrile, CH CN.
3
6.4 Ammonia solution, w(NH ) = 25 % mass fraction (250 g/kg).
3
6.5 Ammonium acetate, w(CH COONH ) = 97 % mass fraction (970 g/kg).
3 4
6.6 Methanol, CH OH, blank-value free.
3
NOTE The quality of methanol is checked by evaporating 10 ml of methanol with a gentle stream of nitrogen
gas (6.13) to 0,5 ml and determining levels according to this document.
6.7 Reference substances, see Table 1.
Reference substances are analytical standards used for quantitative determination of the method
analytes. Use only reference substances or solutions, where the content of linear isomers is at least
95 %. Make sure that the individual reference substances do not contain detectable concentrations of
other target analytes to be determined by analysing alternate lots or second sources.
NOTE Solutions of reference substances are commercially available.
6.8 Internal standard substances, see Table 3.
Internal standard substances are labelled forms of the reference substances to be used in the analytical
procedure to correct for recovery due to losses of analyte or changes in analytical conditions that could
result in bias. Make sure that the internal standard substances do not contain detectable concentrations
of the analytes to be determined by analysing new lots using this document.
NOTE Solutions of internal standard substances are commercially available.
6.9 Preparation of the solutions
Calculate the concentration of all reference substances and internal standard solutions with regard to
the anion content.
Store the solutions at (5 ± 3) °C in the dark, protected against evaporation. Bring them to room
temperature prior to use (i.e. before dilution or spiking or injection).
6.9.1 Individual stock solutions of the reference substances
Stock solutions of the individual reference substances (6.7) in methanol (6.6) or acetonitrile (6.3) should
be of mass concentration to enable dilution to the desired range, e.g. 50 μg/ml each.
6.9.2 Individual stock solutions of internal standard substances
Stock solutions of the indivi
...

SLOVENSKI STANDARD
oSIST ISO/FDIS 21675:2019
01-oktober-2019
Kakovost vode - Določevanje polifluoriranih alkilnih spojin (PFAS) v vodi - Metoda
z ekstrakcijo na trdni fazi in s tekočinsko kromatografijo-tandemsko masno
spektrometrijo (LC-MS/MS)
Water quality - Determination of polyfluorinated alkyl substances (PFAS) in water -
Method using solid phase extraction and liquid chromatography-tandem mass
spectrometry (LC-MS/MS)
Qualité de l'eau - Détermination des substances d'alkyle perfluorés et polyfluorés (SPFA)
dans l'eau - Méthode par extraction en phase solide et chromatographie liquide et
spectrométrie de masse en tandem (CL-SM/SM)
Ta slovenski standard je istoveten z: ISO/FDIS 21675:2019
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
oSIST ISO/FDIS 21675:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST ISO/FDIS 21675:2019

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oSIST ISO/FDIS 21675:2019
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 21675
ISO/TC 147/SC 2
Water quality — Determination of
Secretariat: DIN
perfluoroalkyl and polyfluoroalkyl
Voting begins on:
2019­07­10 substances (PFAS) in water — Method
using solid phase extraction and
Voting terminates on:
2019­09­04
liquid chromatography-tandem mass
spectrometry (LC-MS/MS)
Qualité de l'eau — Détermination des substances d'alkyle perfluorés
et polyfluorés (SPFA) dans l'eau — Méthode par extraction en phase
solide et chromatographie liquide et spectrométrie de masse en
tandem (CL-SM/SM)
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 21675:2019(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2019

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oSIST ISO/FDIS 21675:2019
ISO/FDIS 21675:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 2
5 Interferences . 4
5.1 Interferences with sampling and extraction . 4
5.2 Interferences with LC­MS/MS. 4
6 Reagents . 4
7 Apparatus . 7
8 Sampling . 8
9 Procedure. 8
9.1 Solid-phase extraction . 8
9.1.1 General. 8
9.1.2 Sample preparation . 8
9.1.3 Conditioning of the solid-phase extraction material . 9
9.1.4 Sample extraction . 9
9.1.5 Elution . 9
9.2 LC­MS/MS operating conditions .10
9.3 Blank determination .12
9.4 Identification .12
10 Calibration .13
10.1 General requirements .13
10.2 Calibration using an external standard .13
10.3 Calibration using an internal standard .14
11 Calculation .15
11.1 Use of a calibration curve to determine concentration .15
11.2 Calculation of concentration using calibration with external standards .15
11.3 Calculation of concentration using calibration with internal standards .16
11.4 Treatment of results outside the calibration range .16
12 Determination of analyte recovery .16
12.1 Recovery .16
12.2 Recovery of internal standards .17
13 Expression of results .18
14 Test report .18
Annex A (informative) Examples of suitable sorbents .19
Annex B (informative) Examples of suitable LC columns .20
Annex C (informative) Examples of suitable LC-MS/MS conditions .21
Annex D (normative) Filtration and extraction of suspended matter in the sample .25
Annex E (informative) Examples of chromatographic separation of individual linear and
branched PFAS isomers .27
Annex F (informative) Rapid method by direct injection .31
Annex G (informative) Rapid method by online solid phase extraction LC-MS/MS .32
Annex H (informative) Performance data by DIN 38407-42 for selected PFAS .35
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Annex I (informative) Performance data .37
Bibliography .42
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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
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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).
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URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
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oSIST ISO/FDIS 21675:2019
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 21675:2019(E)
Water quality — Determination of perfluoroalkyl and
polyfluoroalkyl substances (PFAS) in water — Method
using solid phase extraction and liquid chromatography-
tandem mass spectrometry (LC-MS/MS)
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document 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.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document
be carried out by suitably qualified staff.
1 Scope
This document specifies a method for the determination of selected perfluoroalkyl and polyfluoroalkyl
substances (PFAS) in non-filtrated waters, for example drinking water, natural water (fresh water and
sea water) and waste water containing less than 2 g/l solid particulate material (SPM) using liquid
chromatography-tandem mass spectrometry (LC-MS/MS). The compounds monitored by this method
are typically the linear isomers. The group of compounds determined by this method are representative
of a wide variety of PFAS. The analytes specified in Table 1 can be determined by this method. The list
can be modified depending on the purpose for which the method is intended. The lower application
range of this method can vary depending on the sensitivity of the equipment used and the matrix of the
sample. For most compounds to which this document applies ≥0,2 ng/l as limit of quantification can be
achieved. Actual levels can depend on the blank levels realized by individual laboratory.
The applicability of the method to further substances, not listed in Table 1, or to further types of water
is not excluded, but is intended to be validated separately for each individual case.
NOTE 1 PFAS is used in this document to describe the analytes monitored. Many of the compounds in Table 1
are perfluoroalkyl and are also considered polyfluoroalkyl substances
NOTE 2 The linear PFAS isomers are specified in this document. The branched isomers can be present in
environmental samples, especially for PFOS. Annex E provides an example of an analytical approach to the
chromatographic and spectroscopic separation of individual isomers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 5667­1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667­3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 21253­1, Water quality — Multi-compound class methods — Part 1: Criteria for the identification of
1)
target compounds by gas and liquid chromatography and mass spectrometry
1) Under preparation. Stage at time of publication: ISO 21253­1.
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3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org ./obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
perfluoroalkyl and polyfluoroalkyl substances
PFAS
commonly used international abbreviation for organic compounds with replacement of most or all
hydrogen atoms by fluorine in the aliphatic chain structure
Note 1 to entry: The term is used in the broader sense for per- and polyfluoroalkyl substances (PFAS) and per-
and polyfluorinated compounds (PFC) as well.
4 Principle
The analytes listed in Table 1 are extracted from the water sample by solid-phase extraction
using a weak anion exchange sorbent followed by solvent elution and determination by liquid
chromatography-tandem mass-spectrometry.
The user should be aware that each analyte has its own specific optimum conditions and therefore
modification of the analyte list could require the specification of additional conditions for each
additional parameter.
Table 1 — Analytes determinable by this method
a b
Analyte IUPAC name Formula Abbreviation CAS-RN
Perfluoro-n­ 1,1,2,2,3,3,4,4,4-Nonafluorobutane-1-sul­ C HF O S PFBS 375-73-5
4 9 3
butanesulfonic acid fonic acid
Perfluoro-n­ 1,1,2,2,3,3,4,4,5,5,6,6,6-Tridecafluorohex­ C HF O S PFHxS 355-46-4
6 13 3
hexanesulfonic acid ane­1­sulfonic acid
Perfluoro-n­ 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7­Pentade­ C HF O S PFHpS 375-92-8
7 15 3
heptanesulfonic acid cafluoroheptane-1-sulfonic acid
Perfluoro-n­ 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8­Heptade­ C HF O S PFOS 1763-23-1
8 17 3
octanesulfonic acid cafluorooctane-1-sulfonic acid
Perfluoro-n­ 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10­Hen­ C HF O S PFDS 335-77-3
10 21 3
decanesulfonic acid icosafluorodecane-1-sulfonic acid
Perfluorooctanesulfo­ 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8­Heptade­ C H F NO S FOSA 754-91-6
8 2 17 2
namide cafluoro-1-octanesulfonamide
N-methyl 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8­Heptade­ C H F NO S N­MeFOSA 31506-32-8
9 4 17 2
perfluorooctanesulfo­ cafluoro-N-methyl-1-octanesulfonamide
namide
N-ethyl N-Ethyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-he C H F NO S N­EtFOSA 4151-50-2
10 6 17 2
perfluorooctanesulfo­ ptadecafluorooctane-1-sulfonamide
namide
N-methyl 2­[1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8­Hepta­ C H F NO S N­MeFOSAA 2355-31-9
11 6 17 4
perfluorooctanesulfon­ decafluorooctylsulfonyl(methyl)amino]
amidoacetic acid acetic acid
N-ethyl 2-[Ethyl(1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8 C H F NO S N­EtFOSAA 2991-50-6
12 8 17 4
perfluorooctanesulfon­ -heptadecafluorooctylsulfonyl)amino]
amidoacetic acid acetic acid
a
IUPAC: International Union of Pure and Applied Chemistry.
b
CAS-RN: Chemical Abstract Services Registry Number.
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Table 1 (continued)
a b
Analyte IUPAC name Formula Abbreviation CAS-RN
6:2 Fluorotelomer sul­ 3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluorooc­ C H F O S 6:2 FTSA 27619-97-2
8 5 13 3
fonic acid tane­1­sulfonic acid
8:2 Fluorotelomer sul­ 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10­Heptade­ C H F O S 8:2 FTSA 39108-34-4
10 5 17 3
fonic acid cafluorodecane-1-sulfonic acid
9-Chlorohexade­ 2­(6­Chloro­1,1,2,2,3,3,4,4,5,5,6,6­do­ C HClF O S 9Cl­PF3ONS 73606-19-6
8 16 4
cafluoro-3-oxanon­ decafluorohexoxy)-1,1,2,2-tetrafluo­
ane­1­sulfonic acid roethanesulfonic acid
Perfluoro-n­butanoic 2,2,3,3,4,4,4-Heptafluorobutanoic acid C HF O PFBA 375-22-4
4 7 2
acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,5-Nonafluoropentanoic acid C HF O PFPeA 2706-90-3
5 9 2
pentanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,6-Undecafluorohexa­ C HF O PFHxA 307-24-4
6 11 2
hexanoic acid noic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,7-Tridecafluorohep­ C HF O PFHpA 375-85-9
7 13 2
heptanoic acid tanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluo­ C HF O PFOA 335-67-1
8 15 2
octanoic acid rooctanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9­Heptade­ C HF O PFNA 375-95-1
9 17 2
nonanoic acid cafluorononanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10­Non­ C HF O PFDA 335-76-2
10 19 2
decanoic acid adecafluorodecanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFUnDA 2058-94-8
11 21 2
undecanoic acid 11,11,11-Henicosafluoroundecanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFDoDA 307-55-1
12 23 2
dodecanoic acid 11,11,12,12,12-Tricosafluorododecanoic
acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFTrDA 72629-94-8
13 25 2
tridecanoic acid 11,11,12,12,13,13,13-Pentacosafluorotri­
decanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFTeDA 376-06-7
14 27 2
tetradecanoic acid 11,11,12,12,13,13,14,14,14­Hepta­
cosafluorotetradecanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFHxDA 67905-19-5
16 31 2
hexadecanoic acid 11,11,12,12,13,13,14,14,15,15,16,16,
16-Hentriacontafluorohexadecanoic acid
Perfluoro-n­ 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10, C HF O PFOcDA 16517-11-6
18 35 2
octadecanoic acid 11,11,12,12,13,13,14,14,15,15,16,16,
17,17,18,18,18-Pentatriacontafluoroocta­
decanoic acid
8:2 Fluorotelomer 3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Hexade­ C H F O 8:2 FTUCA 70887-84-2
10 2 16 2
unsaturated carboxylic cafluorodec-2-enoic acid
acid
8:2 Polyfluoroalkyl Bis(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10­he C H F O P 8:2 diPAP 678-41-1
20 9 34 4
phosphate diester ptadecafluorodecyl) hydrogen phosphate
Hexafluoropropylene 2,3,3,3-Tetrafluoro-2-(1,1,2,2,3,3,3- C HF O HFPO­DA 13252-13-6
6 11 3
oxide dimer acid heptafluoropropoxy)propanoic acid
4,8-Dioxa-3H-perfluor­ 2,2,3-Trifluoro-3-[1,1,2,2,3,3-hex­ C H F O DONA 919005-14-4
7 2 12 4
ononanoic acid afluoro-3-(trifluoromethoxy)propoxy]
propanoic acid
a
IUPAC: International Union of Pure and Applied Chemistry.
b
CAS-RN: Chemical Abstract Services Registry Number.
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5 Interferences
5.1 Interferences with sampling and extraction
Sample bottles (7.1) shall consist of materials that do not contaminate or change the composition of the
sample during sample storage. All types of fluoropolymer plastics, including polytetrafluoroethylene
(PTFE) and fluoroelastomer materials, shall be avoided during sampling, sample storage and extraction.
Sample bottles (7.1) shall be checked for possible background contamination before use. If background
contamination is suspected or detected in sample bottles (7.1), then wash sample bottles (7.1) with
water (6.1) and methanol (6.6) prior to use. To avoid cross contamination, the sample bottles (7.1) should
only be used once. The use of intermediate sample tubes (7.6) and vials (7.10) should be limited in the
overall process to avoid contamination of loss by sorption. To avoid losses resulting from adsorption of
target analytes to the wall of sample bottle (7.1) and reservoir column (7.4), extract all of the sample
from the sample bottle (7.1) and rinse the wall of sample bottle (7.1) and reservoir column (7.4) with
methanol (6.6).
Commercially available adsorbent materials often vary in quality or activity. Considerable batch-
to-batch differences in quality and selectivity of these materials are possible. The recovery of a
single substance may also vary with respect to its concentration. Therefore, check analyte recovery
periodically at different concentrations and whenever new batches/lots of reagents or labware are
used (12.1).
5.2 Interferences with LC-MS/MS
Substances with similar retention times that can produce ions with similar mass to charge ratios (m/z)
to those produced by the analytes of interest may interfere with the determination.
These interferences may lead to incompletely resolved signals and/or additional signals in the mass
chromatograms of target substances. Depending on their levels in the sample, such substances may
affect the accuracy and precision of the results. The chromatographic separation is different with the
LC column (see Annex C for examples). As long as the peak of interest can be separately integrated from
interferences, it may be used.
Matrix interferences may be caused by contaminants that are co-extracted from the samples. The extent
of matrix interferences varies considerably, depending on the nature of the samples. In drinking water
and ground water, matrix interferences are usually negligible, whereas waste water and sea water
matrices can be affected by matrix interferences that lead to ionization suppression or enhancement
resulting in bias or reduced sensitivity of the method. As long as the required limits of quantification
can be achieved in samples, samples can be diluted to minimize matrix effects.
Interferences arising directly from analytical instruments can be significant for unmodified commercial
LC systems because many parts are made of PTFE and other fluoropolymers. It is necessary to check
for possible blank contamination from the individual parts, such as tubing, solvent inlet filters, valve
seals and the degassing equipment, and replace these with materials such as stainless steel and
polyetheretherketone (PEEK), where possible.
NOTE Background contamination can arise from within the instrument. A delay column can be attached
between the solvent mixer and injection valve to chromatographically resolve these background contaminants
from the instrument and/or mobile phases from the target analytes.
The LC-vial caps shall be free of fluoropolymer material. Efforts should be taken to minimize background
levels in procedural blank materials such that the procedural blank, including the instrumental blank,
is at least 10­fold below the reporting limit.
6 Reagents
Whenever possible, use certified or analytical-grade reagents or residue free-analytical grade
reagents stored in glass or polypropylene containers with metal or polypropylene lined caps. Avoid
using reagents with fluoropolymer lined caps and check contamination levels of target substances
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using repeated blank determinations. Carry out additional cleaning or conditioning steps to ensure
background levels are minimized, if necessary.
6.1 Water, blank-value free, e.g. complying with grade 1 as specified in ISO 3696.
Purified laboratory water can be used, but should be confirmed to be free of PFAS. The quality of water
is checked by the same procedure given in 9.3.
6.2 Acetic acid, w(CH COOH) = 99,9 % mass fraction (999 g/kg).
3
6.3 Acetonitrile, CH CN.
3
6.4 Ammonia solution, w(NH ) = 25 % mass fraction (250 g/kg).
3
6.5 Ammonium acetate, w(CH COONH ) = 97 % mass fraction (970 g/kg).
3 4
6.6 Methanol, CH OH, blank­value free.
3
NOTE The quality of methanol is checked by evaporating 10 ml of methanol with a gentle stream of nitrogen
gas (6.13) to 0,5 ml and determining levels according to this document.
6.7 Reference substances, see Table 1.
Reference substances are analytical standards used for quantitative determination of the method
analytes. Use only reference substances or solutions, where the content of linear isomers is at least
95 %. Make sure that the individual reference substances do not contain detectable concentrations of
other target analytes to be determined by analysing alternate lots or second sources.
NOTE Solutions of reference substances are commercially available.
6.8 Internal standard substances, see Table 3.
Internal standard substances are labelled forms of the reference substances to be used in the analytical
procedure to correct for recovery due to losses of analyte or changes in analytical conditions that could
result in bias. Make sure that the internal standard substances do not contain detectable concentrations
of the analytes to be determined by analysing new lot
...