prEN ISO 23161

Soil quality - Determination of selected organotin compounds - Gas-chromatographic method (ISO/FDIS 23161:2016)

2017-06-06: WI abandoned to follow cancellation of WI at ISO level (ISO notification received in dataservice on 2017-06-06).
MINOR REVISION

Bodenbeschaffenheit - Bestimmung ausgewählter Organozinnverbindungen - Gaschromatographisches Verfahren

Qualité du sol - Dosage d'une sélection de composés organostanniques - Méthode par chromatographie en phase gazeuse (ISO/FDIS 23161:2016)

Kakovost tal - Določevanje izbranih organokositrovih spojin - Metoda plinske kromatografije (ISO/FDIS 23161:2016)

General Information

• Status: Not Published
• ICS: 13.080.10 - Chemical characteristics of soils
• Technical Committee: CEN/TC 444 - Environmental characterization
• Drafting Committee: CEN/TC 444/WG 2 - Organic analysis
• Current Stage: 3098 - Decision to reject - Consensus building
• Start Date: 06-Jun-2017
• Completion Date: 14-Apr-2025
• Ref Project: oSIST prEN ISO 23161:2017 - Soil quality - Determination of selected organotin compounds - Gas-chromatographic method (ISO/FDIS 23161:2016)

Relations

• Revises: EN ISO 23161:2011 - Soil quality - Determination of selected organotin compounds - Gas-chromatographic method (ISO 23161:2009)
• Effective Date: 18-Jan-2023

Overview

prEN ISO 23161 / ISO/FDIS 23161:2016 defines a gas‑chromatographic method for the identification and quantification of selected organotin compounds in soils and soil‑like materials (sediments, sludges, wastes). This second‑edition, minor revision replaces ISO 23161:2009 and provides procedures for sample pretreatment, extraction, derivatization, clean‑up, chromatographic separation and quantification. The method is applicable to environmental monitoring where limits of quantification are around 10 µg/kg.

Key topics and technical requirements

• Target analytes: selected organotin cations (e.g., MBT, DBT, TBT, MOT, DOT, TPhT, TCyT) and peralkylated compounds (e.g., tetrabutyltin, TTBT). Organotin cations are measured after derivatization; TTBT is determined directly.
• Sample types: soils, sediments, sludges and wastes (soil‑like materials).
• Sample pretreatment: freeze‑drying and grinding to achieve homogeneity for organotin cations; field‑moist analysis required for volatile peralkylated compounds (TTBT) to avoid losses.
• Extraction and derivatization: two alternative extraction routes are specified:
  • acidic extraction (acetic acid) with in‑situ derivatization using a tetraethylborate reagent, or
  • alkaline treatment (methanolic KOH) with in‑situ derivatization and simultaneous extraction into hexane.
• Clean‑up: guidance on silica and aluminium oxide clean‑up and additional procedures to reduce matrix interferences.
• Measurement and identification: gas chromatography (GC) with appropriate detectors; GC‑MS identification guidance is included for confirmatory analysis.
• Quality control: calibration, internal standards, recovery checks, expression of results, validation and reporting requirements are specified to ensure reliable quantification.

Practical applications and users

• Environmental testing and soil quality assessment laboratories monitoring organotin contamination.
• Regulatory agencies and compliance laboratories conducting site assessments and pollution control.
• Research institutions studying organotin fate in soils, sediments and waste matrices.
• Remediation practitioners needing validated analytical data to guide cleanup and verification.

The standard supports consistent, comparable results for organotin monitoring and risk assessment, enabling robust decision‑making in environmental management.

Related standards

Normative references cited in the document that support analytical quality and sample handling include:

• ISO 3696 - Water for analytical laboratory use
• ISO 11465 - Determination of dry matter and water content
• ISO 16720 - Pretreatment by freeze‑drying
• ISO 22892 - Guidelines for GC/MS identification

Keywords: ISO 23161, soil quality, organotin compounds, gas‑chromatographic method, derivatization, TBT, TTBT, environmental monitoring, soil analysis, GC‑MS.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2017
.DNRYRVWWDO'RORþHYDQMHL]EUDQLKRUJDQRNRVLWURYLKVSRMLQ0HWRGDSOLQVNH
NURPDWRJUDILMH,62)',6
Soil quality - Determination of selected organotin compounds - Gas-chromatographic
method (ISO/FDIS 23161:2016)
Bodenbeschaffenheit - Bestimmung ausgewählter Organozinnverbindungen -
Gaschromatographisches Verfahren (ISO/FDIS 23161:2016)
Qualité du sol - Dosage d'une sélection de composés organostanniques - Méthode par
chromatographie en phase gazeuse (ISO/FDIS 23161:2016)
Ta slovenski standard je istoveten z: prEN ISO 23161
ICS:
13.080.10 .HPLMVNH]QDþLOQRVWLWDO Chemical characteristics of
soils
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23161
ISO/TC 190/SC 3
Soil quality — Determination of
Secretariat: DIN
selected organotin compounds — Gas-
Voting begins on:
2016­12-02 chromatographic method
Voting terminates on:
Qualité du sol — Dosage d’une sélection de composés
2017­02­24
organostanniques — Méthode par chromatographie en phase gazeuse
ISO/CEN PARALLEL PROCESSING
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 23161:2016(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 2016

ISO/FDIS 23161:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
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Tel. [phone]
Fax [phone]
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www.iso.org
ii © ISO 2016 – All rights reserved

ISO/FDIS 23161:2016(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Principle . 2
5 Reagents . 4
5.1 General . 4
5.2 Chemicals . 4
5.3 Standards . 5
5.4 Preparation of reagents and solutions . 6
5.5 Clean­up . 7
6 Apparatus . 8
6.1 Requirements for glassware . 8
6.2 Sampling apparatus . 8
6.3 Additional apparatus . 8
7 Procedure. 9
7.1 Sampling and sample pretreatment . 9
7.2 Sample extraction . 9
7.2.1 General. 9
7.2.2 Acidic extraction and derivatization of an aliquot .10
7.2.3 Alkaline treatment and in situ derivatization .10
7.2.4 Separate determination of TTBT in the field-moist sample .10
7.3 Clean­up of the extract .11
7.3.1 General.11
7.3.2 Silica and aluminium oxide clean­up.11
7.4 Determination of dry mass .11
7.5 Measurement .11
7.5.1 Gas chromatographic separation .11
7.5.2 Detection and identification .12
8 Calibration .12
9 Recovery rates of the internal standard compounds .13
10 Quantification .14
11 Expression of results .15
12 Validation .15
13 Test report .15
Annex A (informative) Information about the procedure .16
Annex B (informative) Additional clean-up procedures .18
Annex C (informative) Information about typical instrumental conditions .20
Annex D (informative) Information about GC-MS identification.31
Annex E (informative) Validation data .33
Bibliography .37
ISO/FDIS 23161:2016(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
committee has been established has the right to be represented on that committee. International
organizations, governmental and non­governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical
methods and soil characteristics.
This second edition cancels and replaces the first edition (ISO 23161:2009), of which it constitutes a
minor revision.
The changes compared to the previous edition are as follows:
— the Note to Clause 1 and Table 2 have been moved to Clause 4;
— former Note 4 to Clause 4 has been changed to normal text and moved above Note 1;
— former second sentence in 5.5.5 has been changed to Note;
— in 7.2.2 and 7.2.3, a Note has been added;
— the presentation of tables in Annex E has been improved;
— the Bibliography has been updated.
iv © ISO 2016 – All rights reserved

ISO/FDIS 23161:2016(E)
Introduction
It is absolutely essential that tests conducted in accordance with this document be carried out by
suitably qualified staff.
It can be noted whether, and to what extent, particular problems will require the specification of
additional boundary conditions.
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23161:2016(E)
Soil quality — Determination of selected organotin
compounds — Gas-chromatographic method
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 and to
ensure compliance with any national regulatory conditions.
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 gas-chromatographic method for the identification and quantification of
organotin compounds (OTCs) in soils as specified in Table 1.
This document is also applicable to samples from sediments, sludges and wastes (soil­like materials).
The working range depends on the detection technique used and the amount of sample taken for
analysis.
The limit of quantification for each compound is about 10 µg/kg.
Table 1 — Organotin compounds, which can be determined in accordance with this document
(4−n)+
R Sn R n Name Acronym
n
a
Organotin cations
3+
BuSn Butyl 1 Monobutyltin cation MBT
2+
Bu Sn Butyl 2 Dibutyltin cation DBT
+
Bu Sn Butyl 3 Tributyltin cation TBT
3+
OcSn Octyl 1 Monooctyltin cation MOT
2+
Oc Sn Octyl 2 Dioctyltin cation DOT
+
Ph Sn Phenyl 3 Triphenyltin cation TPhT
+
Cy Sn Cyclohexyl 3 Tricyclohexyltin cation TCyT
Peralkylated organotin
Bu Sn Butyl 4 Tetrabutyltin TTBT
a
Organotin compounds are measured after derivatization.
Organotin cations can only be determined in accordance with this document after derivatization. The
anionic part bound to the organotin cation is mainly dependent on the chemical environment and is
not determined using this method. The peralkylated organotin compounds behave in a completely
different way from their parent compounds. Tetraalkylated organotin compounds which are already
peralkylated, such as tetrabutyltin, are determined directly without derivatization.
The properties such as particle size distribution, water content and organic matter content of the solids
to be analysed using this document vary widely. Sample pretreatment is designed adequately with
respect to both the properties of the organotin compounds and the matrix to be analysed.
ISO/FDIS 23161:2016(E)
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 11465, Soil quality — Determination of dry matter and water content on a mass basis —
Gravimetric method
ISO 16720, Soil quality — Pretreatment of samples by freeze-drying for subsequent analysis
ISO 22892, Soil quality — Guidelines for the identification of target compounds by gas chromatography and
mass spectrometry
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:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
organotin compound
substance containing 1 to 4 Sn­C bonds
Note 1 to entry: The number of Sn-C bonds is a measure for the degree of substitution.
3.2
organotin cation
part of the organotin compound (3.1) that contains all Sn-C bonds and is formally charged
3.3
organotin cation derivatives
non-dissociated tetrasubstituted organotin compounds which are produced by derivatization
3.4
solid
soil, sediment, sludge and waste (soil­like material)
4 Principle
For the ionic and the non­ionic organotin compounds (see Table 1), a different sample pretreatment and
sample preparation are necessary. For the determination of organotin cations, laboratory samples are
pretreated by freeze drying and grinding. This procedure enables to achieve homogeneity of the sample
to be achieved. The determination of non­ionic TTBT cannot be carried out with freeze­dried materials
due to evaporation losses; thus, it shall be determined in the field-moist sample. Organotin cations can
only be determined after derivatization, whereas TTBT is already peralkylated and can be determined
without derivatization (see the flowchart in Figure 1).
2 © ISO 2016 – All rights reserved

ISO/FDIS 23161:2016(E)
Figure 1 — Flowchart for the pretreatment and analysis of selected organotin compounds
For the determination of organotin compounds, two alternative extraction methods are given, both
followed by in situ derivatization with a tetraethylborate compound and simultaneous extraction
with hexane:
a) treatment with acetic acid;
b) treatment with methanolic potassium hydroxide.
Treatment with potassium hydroxide provides some degree of digestion and is recommended especially
when the solid contains high amounts of organic and biological materials.
NOTE 1 If it is necessary to take a large amount of sample, extraction and derivatization can be done in two
steps. An aliquot of the extract can be taken for derivatization. This also applies for samples with high levels of
contamination by organotin compounds.
ISO/FDIS 23161:2016(E)
NOTE 2 During in situ derivatization, the solid phase is still present. This supports the extraction by
continuous changing of the polar organotin cations to the non­polar organotin cation derivates. In situ methods
can improve the extraction efficiency, particularly for monoalkylated organotin compounds.
NOTE 3 Other extraction techniques can be applied if a comparable extraction efficiency is achieved.
When applying this method to the determination of other organotin compounds not specified in
the scope, its suitability has to be proven by proper in-house validation experiments, e.g. methyltin
compounds (see Table 2). Methyltin cations are unlikely to evaporate from aqueous solvents, but
peralkylated methyltin compounds are volatile and subject to losses (see C.3). Therefore, additional
precautions are established.
Table 2 — Methyltin compounds
(4−n)+
R Sn R n Name Acronym
n
3+
MeSn Methyl 1 Monomethyltin cation MMT
2+
Me Sn Methyl 2 Dimethyltin cation DMT
+
Me Sn Methyl 3 Trimethyltin cation TMT
The internal standard mix comprises four compounds representing four alkylation states in order to
mimic the behaviour of the target compounds. After alkylation, they cover a wide range of volatility.
A recovery of at least 80 % for derivatization/extraction and again 80 % for each clean-up step of the
internal standard compounds should be achieved. (For more information, see A.3.) Tetraalkylborate
is very reactive and will also alkylate other compounds in the matrix. Those compounds (and also
boroxines) may interfere with the target compounds during gas chromatographic determination and
influence detection. In order to protect the column and to reduce the interference in chromatography,
it will be necessary to apply a pre-cleaning step to most samples. Clean-up with silica or aluminium
oxide is the minimum; further clean­up steps (e.g. aluminium oxide/silver nitrate, silica/silver nitrate,
pyrogenic copper; see Annex B) may be applied if necessary.
The determination of the tetrasubstituted organotin compounds is carried out after clean­up and
concentration steps by separation with capillary gas chromatography and detected with a suitable
system [mass spectrometer (MS), (MS/MS), flame photometric detector (FPD), atomic absorption
spectrometer (AAS), atomic emission detector (AED), inductively coupled plasma/mass spectrometer
ICP/MS]. The concentrations are determined by calibration over the total procedure using aqueous
multi­component calibration standard solutions in accordance with 5.4.3.
5 Reagents
5.1 General
Use reagents of highest purity, typically of pesticide grade or better. The reagents may contain
impurities of organotin compounds. It is absolutely essential to verify the blanks.
The water shall be free of interferences. Use water in accordance with Grade 3 of ISO 3696.
5.2 Chemicals
5.2.1 Acetic acid, CH COOH, glacial.
5.2.2 Sodium hydroxide solution, NaOH, 40 % (m/V).
5.2.3 Sodium acetate, CH COONa.
5.2.4 Sodium sulfate, Na SO , anhydrous.
2 4
4 © ISO 2016 – All rights reserved

ISO/FDIS 23161:2016(E)
5.2.5 Potassium hydroxide, KOH.
5.2.6 Silica gel, grain size 0,085 mm to 0,28 mm (63 mesh to 200 mesh).
5.2.7 Aluminium oxide, Al O , alkaline.
2 3
5.2.8 Tetrahydrofurane, C H O, free of peroxides, free of water.
4 8
5.2.9 Acetone, (CH ) CO.
3 2
5.2.10 Hexane, C H .
6 14
NOTE Both n-hexane and 2-methylpentane (i­hexane) have been found to be suitable.
5.2.11 Tetraethylborate compound, e.g sodium tetraethylborate, NaB(C H ) .
2 5 4
NOTE The active species during derivatization is the tetraethylborate anion. The choice of the cation
is arbitrary. Sodium tetraethylborate was chosen since it is commercially available. In principle, any other
tetraethylborate compound can be used for analysis, including complexes formed with tetrahydrofuran (THF). A
simple and rapid synthesis of a suitable derivatization agent is described in A.1.
WARNING — Sodium tetraethylborate may contain traces of triethylboron, which may cause
instantaneous combustion.
5.2.12 Methanol, CH OH.
5.2.13 Dichloromethane, CH Cl .
2 2
5.3 Standards
WARNING — Organotin compounds vary largely regarding toxicological properties towards
mammals with respect to the alkylation stage and type of alkyl group. Cautious handling of
reagents is mandatory at any time.
Table 3 lists the standards used for calibration of the target compounds (solution A), internal standards
(solution B) and injection standard (solution C). Additional information is provided concerning weighing
factors for calculation to organotin cations (for 100 % purity of the substances).
Table 3 — Standards and internal standards for calibration of target compounds
a b c
No. Standard Abbreviation Formula CAS-RN WF Solution
5.3.1 Monobutyltin trichloride MBTCl C H SnCl 1118­46­3 0,623 A
4 9 3
5.3.2 Dibutyltin dichloride DBTCl (C H ) SnCl 683­18­1 0,767 A
4 9 2 2
5.3.3 Tributyltin chloride TBTCl (C H ) SnCl 1461­22­9 0,891 A
4 9 3
5.3.4 Tetrabutyltin TTBT (C H ) Sn 1461­25­2 1,000 A
4 9 4
5.3.5 Monooctyltin trichloride MOTCl C H SnCl 3091­25­6 0,686 A
8 17 3
5.3.6 Dioctyltin dichloride DOTCl (C H ) SnCl 3542­36­7 0,830 A
8 17 2 2
5.3.7 Triphenyltin chloride TPhTCl (C H ) SnCl 639­58­7 0,908 A
6 5 3
a
Chemical Abstracts Registration Number.
b
WF= Weighing factor = Molar mass of organotin cation/molar mass of organotin compound.
c
A for the multicomponent­standard solution in methanol.
B for the solution of the internal standards in methanol.
C for the solution of the injection standards in hexane.
ISO/FDIS 23161:2016(E)
Table 3 (continued)
a b c
No. Standard Abbreviation Formula CAS-RN WF Solution
5.3.8 Tricyclohexyltin chloride TCyTCl (C H ) SnCl 3091­32­5 0,912 A
6 11 3
Internal standards
5.3.9 Monoheptyltin trichloride MHTCl C H SnCl 59344­47­7 0,672 B
7 15 3
5.3.10 Diheptyltin dichloride DHTCl (C H ) SnCl 74340­12­8 0,817 B
7 15 2 2
5.3.11 Tripropyltin chloride TPTCl (C H ) SnCl 2279­76­7 0,875 B
3 7 3
5.3.12 Tetrapropyltin TTPT (C H ) Sn 2176­98­9 1,000 B
3 7 4
5.3.13 Tetrapentyltin TTPeT (C H ) Sn 3765­65­9 1,000 C
5 11 4
a
Chemical Abstracts Registration Number.
b
WF= Weighing factor = Molar mass of organotin cation/molar mass of organotin compound.
c
A for the multicomponent­standard solution in methanol.
B for the solution of the internal standards in methanol.
C for the solution of the injection standards in hexane.
5.4 Preparation of reagents and solutions
5.4.1 General requirements
Prepare the following (see also Table 3):
— multicomponent standard stock solution A in methanol (e.g. 1 mg/ml);
— multicomponent standard spiking solutions for calibration, by diluting solution A with methanol;
— stock solution B of internal standards in methanol (e.g. 1 mg/ml);
— spiking solution of the internal standards, by diluting solution B with methanol (e.g. 100 ng/ml);
— stock solution C of the injection standard in methanol (e.g. 2 mg/ml);
— injection standard solution, by diluting solution C (e.g. 2 µg/ml).
5.4.2 Blank solution
Add 20 ml of water (5.1) to an Erlenmeyer flask with a ground joint or a screw-capped
[polytetrafluoroethylene (PTFE) lined] vial.
5.4.3 Aqueous calibration solutions (multicomponent solution of organotin compounds in water)
For each working range, prepare at least six calibration solutions with appropriate concentration levels.
Add 20 ml of water (5.1) to an Erlenmeyer flask with a ground joint or a screw-capped (PTFE-lined) vial.
While stirring vigorously, pipette an appropriate volume of the respective spiking solution underneath
the surface and ensure that the spiking solution is well distributed in the water. Stir for additional 20 min.
5.4.4 Methanolic potassium hydroxide solution
Prepare a solution of 25 % (m/V) potassium hydroxide (5.2.5) in methanol (5.2.12). This is the
methanolic potassium hydroxide solution.
6 © ISO 2016 – All rights reserved

ISO/FDIS 23161:2016(E)
5.4.5 Acetate buffer solution
Dissolve about 1 mol of sodium acetate (equal to 82 g of anhydrous sodium acetate) (5.2.3) in 500 ml
of water (5.1) in a 1 l volumetric flask. Add sufficient glacial acetic acid (5.2.1) to adjust to a pH of 4,5.
Dilute to volume with water (5.1) and mix well.
5.4.6 Solvent mixture
Prepare a solvent mixture of acetic acid, methanol and water with a volume ratio of 1:1:1.
5.4.7 Derivatization agent
Prepare an approximately 10 % (m/V) solution of tetraethylborate compound (5.2.11) in
tetrahydrofurane (5.2.8).
NOTE This solution is stable for about three months if stored under an inert­gas blanket.
5.5 Clean-up
5.5.1 General requirements
A silica or aluminium oxide clean­up is the minimum requirement. Further clean­up steps (aluminium
oxide/silver nitrate, silica/silver nitrate, pyrogenic copper) may be applied if necessary (see Annex B).
A recovery of >80 % of the internal standards and target compounds shall be achieved for each clean-
up step.
5.5.2 Silica gel for the clean-up column
Heat silica gel (5.2.6) for at least 12 h at (500 ± 20) °C on a quartz plate in a muffle furnace. Ensure that
the temperature does not exceed 520 °C.
Allow the plate to cool in an oven to about 200 °C, transfer the silica to a wide­necked glass bottle and
allow cooling to room temperature in a desiccator.
Add water to the cooled silica until a mass fraction of 3 % is reached. Close the bottle and homogenize
the contents for 2 h on a shaker.
5.5.3 Aluminium oxide for the clean-up column
Activate aluminium oxide (5.2.7) by heating to 600 °C for a minimum of 24 h.
Allow to cool in the oven to about 200 °C, transfer the aluminium oxide to a wide­necked glass bottle
and allow cooling to room temperature in a desiccator.
Add water to the cooled aluminium oxide until a mass fraction of 10 % is reached. Close the bottle and
homogenize the contents for 2 h on a shaker.
5.5.4 Clean-up column
Add about 5 g of adsorbent (5.5.2 or 5.5.3) to one column, and add about 3 g of drying agent. Ensure that
the clean-up column is filled homogeneously, for example, by using hexane as a moistening agent during
the filling process.
Commercially pre-packed columns may be used as an alternative if the requirement for recovery is met.
ISO/FDIS 23161:2016(E)
5.5.5 Eluent for extract cleaning with silica gel
A mixture of hexane (5.2.10) with a more polar solvent can be used as an eluent to obtain a quantitative
elution of all organotin compounds. The concentration of polar solvent in hexane and the volume of
total eluent should be determined prior to application.
NOTE In routine work, about 5 % of acetone (5.2.9) or 20 % of dichloromethane (5.2.13) was used
successfully.
5.5.6 Eluent for extract cleaning with aluminium oxide
Generally, hexane (5.2.10) is used as the eluent. The volume of the eluent should be determined prior to
application.
6 Apparatus
6.1 Requirements for glassware
Customary laboratory glassware shall be used.
All glassware and material that come into contact with the sample or extract shall be thoroughly
cleaned.
6.2 Sampling apparatus
Sampling devices shall not be a source of contamination. The use of stainless steel, glass or PTFE is
recommended.
NOTE For example, poly(vinyl chloride) (PVC) can contain large amounts of organotin compounds.
Containers shall be inert and appropriate for storing and transport.
The size of the container shall be appropriate to ensure sampling of a suitable amount of solid to provide
a representative sample and facilitate a determination in accordance with this document within the
calibrated working range.
6.3 Additional apparatus
Usual laboratory apparatus and the following.
6.3.1 Centrifuge.
WARNING — The use of organic solvents in centrifuges needs to be assessed for safety reasons.
6.3.2 Glass column for clean-up, e.g. length 15 cm, inner diameter 1 cm, with frit, without a cock.
6.3.3 Shaker.
6.3.4 Ultrasonic bath or horn-type transducer.
6.3.5 Analytical balance, with suitable reading accuracy and range.
6.3.6 Concentration apparatus, e.g. rotary evaporator, Kuderna Danish.
6.3.7 Gas chromatograph, equipped with a high-resolution capillary column of suitable polarity and
injector, split or splitless, preferably with an automated sampling device (C.1).
8 © ISO 2016 – All rights reserved

ISO/FDIS 23161:2016(E)
6.3.8 Detectors (for typical detector configurations, see C.2). The following detector types may be
used for the measurement of alkylated organotin compounds:
— atomic absorption spectrometer (AAS), quartz oven, tin(Sn) lamp;
— flame photometric detector (FPD), equipped with a cut-off filter of 590 nm or interference filter
of 610 nm;
— pulsed flame photometric detector (PFPD) equipped with a large pass-band filter working at 610 nm
or 390 nm with a time­selective acquisition;
— mass spectrometer (MS) for electron impact mode (EI­mode);
— atomic emission detector (AED);
— inductively coupled plasma/mass spectrometric detector (ICP/MS).
6.3.9 Data processing system, suitable for the respective detector for acquisition and data evaluation.
7 Procedure
7.1 Sampling and sample pretreatment
Sample pretreatment should be carried out according to ISO 14507 or ISO 16720.
The use of, for example, stainless steel, PTFE and glass is recommended. Store the sample until
pretreatment in a cool place.
If the storage time is less than 48 h, store the sample in a dark, cool place until pretreatment.
If the storage time exceeds 48 h, the sample shall be stored frozen (<−18 °C) in the dark.
The laboratory sample should represent the field sample. The amount of sample taken depends on
homogeneity and on the resulting dry mass after preparation. If necessary, select coarse material and
sieve to particle size <2 mm. Stir with a metal spoon.
For the preparation of freeze-dried samples take, for example, 250 g of original field-moist sample and
proceed with freeze drying in accordance with ISO 16720.
Grind the freeze­dried material, for example, in an agate centrifugal ball mill, to a homogeneous
powdery consistency. Prevent high temperatures in the mill by grinding for a short time.
Determine the dry mass of the freeze-dried material in accordance with ISO 11465.
For the determination of organotin compounds in original field-moist material, take the sieved and
stirred sample as described above. From this homogenized laboratory sample, suitable amounts of sub-
samples (test samples) are taken for subsequent analysis for the determination of organotin compounds
and dry mass in accordance with ISO 11465.
7.2 Sample extraction
7.2.1 General
Add 1 g to 5 g of solid to a container that can be closed [e.g. an Erlenmeyer flask with a ground joint or
a screw-capped vial, polytetrafluoroethylene (PTFE) lined]. It is recommended to choose two samples,
varying in size at least by a factor of 2. Ensure that the mass of analytes in the samples is covered by the
working range.
Pretreat samples of solids, blank solutions (5.4.2) and aqueous calibration solutions (5.4.3) as follows.
ISO/FDIS 23161:2016(E)
7.2.2 Acidic extraction and derivatization of an aliquot
Add an appropriate amount of internal standard mixture and of a solvent mixture of acetic
acid:methanol:water (1:1:1) to the freeze-dried sample to obtain a sample slurry containing 20 % or
less of solid material.
Sonicate for 30 min in an ultrasonic bath.
Transfer all the slurry to a centrifuge glass tube and then centrifuge to obtain a liquid/solid phase
separation. The liquid phase is then transferred by a pipette to another container. The extraction
procedure is repeated in the same way by adding half of the volume of extraction solvent mixture used
for the first extraction step. The two extraction solutions are combined prior to derivatization.
For derivatization, add aqueous sodium hydroxide (5.2.2) to an appropriate aliquot (at least 5 ml) of the
extraction solution obtained above and adjust to pH 4,5 using acetic acid (5.2.1). After the addition of 5 ml
of hexane (5.2.10) and a 10 % solution of tetraethylborate compound (5.2.11) in tetrahydrofurane (5.2.8)
(0,5 ml/g of sample taken), the solution is immediately shaken by hand for 1 min. Afterwards, the whole
mixture is shaken for 20 min on a mechanical shaking machine. The procedure is then repeated. The
hexane phases separated are combined and dried over sodium sulfate (5.2.4) and concentrated to 1 ml.
NOTE In routine work, adjusting to pH 4,0 also gives suitable results.
Blank solutions and aqueous calibration solutions (5.4.2 and 5.4.3) shall be treated in the same way as
the samples.
7.2.3 Alkaline treatment and in situ derivatization
Add an appropriate amount of the internal standard solution and water (5.1) to the freeze­dried sample
to obtain a sample slurry with 20 % or less of solid material.
Shake for about 20 min and ensure that the spiking solution is well distributed in the water or
water/solid slurry.
Add methanolic potassium hydroxide solution (1,2 ml/g of sample taken) (see 5.4.4) and 20 ml of hexane
(5.2.10). Heat to 70 °C for 1 h in a closed container (ensure the tightness). Choose a volume of methanolic
potassium hydroxide solution to ensure that the slurry is alkaline. Instead of treatment at 70 °C for
1 h, ultrasonic treatment (e.g. for a few minutes followed by 1 h of shaking) or treatment overnight at
ambient temperature may be applied.
Add acetic acid (5.2.1) to adjust to a pH of 4,5. Add 10 ml of acetate buffer solution (5.4.5) and shake
for about 1 min. To the buffered solution, add the 10 % solution of tetraethylborate compound in
tetrahydrofurane (see 5.4.7) (0,5 ml/g of sample taken). Shake for about 2 h. Repeat the derivatization
procedure and shake for 1 h minimum. Ensure that the phases are well mixed.
NOTE In routine work, adjusting to pH 4,0 also gives suitable results.
Separate the phases using a centrifuge. Collect the hexane layer and dry it with sodium sulfate (5.2.4),
and reduce the volume of the organic phase to 1 ml using a suitable apparatus, but avoid reduction to
dryness in every case.
Blank solutions and aqueous calibration solutions (5.4.2 and 5.4.3) shall be treated in the same way as
the samples.
7.2.4 Separate determination of TTBT in the field-moist sample
The determination of TTBT can be carried out by extraction of the field-moist sample with hexane
without the derivatization step. Therefore, it is possible to take a larger amount of homogenized field-
moist sample (5 g or more) and to use only tetrapropyltin as the internal standard.
10 © ISO 2016 – All rights reserved

ISO/FDIS 23161:2016(E)
7.3 Clean-up of the extract
7.3.1 General
If necessary, sample extracts shall be subjected to an adsorption chromatography clean-up. If the
chromatographic measurements of the target compounds are disturbed by interferences, apply further
appropriate clean­up procedures (see Annex B) provided a recovery of >80 % of the internal compounds
is achieved for each clean-up step. The reference and blank solutions shall be treated in the same way.
NOTE 1 Triphenyltin elutes later from the clean-up column than the other organotin compounds. If TPHT is
not to be analysed, the clean-up efficiency can be improved by reducing the eluent volume, the water content of
the adsorbent or the concentration of the polar solvent in hexane.
NOTE 2 Boroxins will be formed during derivatization, which can affect the gas chromatography (GC)
column. These are eliminated by silica clean-up with hexane, but can be eluted if acetone is added to the eluent.
An alternative separation method is to shake with sodium hydroxide (NaOH) solution; peralkylated organotin
compounds are stable against NaOH solution.
7.3.2 Silica and aluminium oxide clean-up
Rinse the clean-up column, freshly prepared in accordance with 5.5.4 with 30 ml of hexane (5.2.10).
Transfer the concentrated extract in hexane to the clean­up column (5.5.4). After the extract has
penetrated the top of the adsorbent layer, cautiously add the volume of eluant (5.5.5 or 5.5.6) found to
be necessary.
Collect the eluate and reduce the volume of the organic phase to 1 ml using a suitable apparatus, but
avoid reduction to dryness in every case.
If the chromatography turns out to be unacceptable, apply further clean-up procedures (see Annex B).
7.4 Determination of dry mass
Determine the fraction of dry mass gravimetrically in accordance with ISO 11465. The fraction of dry
mass of original field-moist samples or of freeze-dried materials is expressed as a percentage.
NOTE The following standards can be used for other solids: EN 15934 for sediments or sludges; EN 14346
for wastes.
7.5 Measurement
7.5.1 Gas chromatographic separation
Optimize the instrument in accordance with the manufacturer’s instructions. Ensure at least baseline
separation of the target peaks of interest. Higher resolution is recommended to avoid co­elution of
matrix compounds as far as appropriate (for typical gas chromatographic conditions, see C.1).
The resolution of triphenylethyltin and tricyclohexylethyltin should be at least 0,8.
Prepare injection solutions of blanks, references and samples by adding, for example, 50 µl of injection
standard (see 5.4.1) to the final extract of 1 ml.
Inject an appropriate volume of the prepared sample extracts into the injection port of a gas
chromatograph. Record retention times and the signal intensity of each compound.
Quantify the gas chromatographic signals either as peak areas or as peak heights. In the case of non-
continuous detection (e.g. mass spectrometry), evaluation using peak areas is recommended.
NOTE In this document, only the evaluation using peak areas is described as an example.
ISO/FDIS 23161:2016(E)
7.5.2 Detection and identification
Use an appropriate detector (see 6.3.8) for monitoring the target peaks.
Independent from the detection system, identify the analytes by comparison of the retention times for
samples and references. Minimal requirements for identification are retention times within ±0,02 min
and relative retention times within ±0,1 % over the total run of a chromatogram.
Following the retention time criteria, three identification points are necessary. For GC-MS, this
procedure is described in ISO 22892; each individual mass meeting the criteria gives one identification
point. Identification points for other detectors are described in Table 4. If the detector does not give
three identification points, additional points can be obtained by, for instance, using a second column or
by pattern recognition (see also ISO 22892).
Table 4 — Identification points
Detector Number of identification points Remarks
FPD, PFPD 2
MS 1 for each individual mass Refer to ISO 22892
MS/MS 2 for each mass transfer
MSn 1 for each mass transfer
AED 3 Different spectral lines
ICP/MS 3
AAS 3
8 Calibration
Calibration is carried out by putting standards, including internal standards, through the whole
procedure. The underivatized organotin compounds are added to water to give the aqueous calibration
solutions (5.4.3). The whole procedure of derivatization, extraction, clean­up and concentration is
carried out to establish calibration curves. At least six calibration solutions at different concentrations
should be used to prepare the calibration curve.
For quantification of monobutyltin and monooctyltin compounds, use monoheptyltin trichloride
(MHTCl) as the internal standard; for dibutyltin and dioctyltin compounds, use diheptyltin dichloride
(DHTCl) as the internal standard; and for tributyltin, triphenyltin and tricyclohexyltin compounds,
use tripropyltin chloride (TPTCl) as the internal standard. The recovery of the internal standards
corresponding to each group of organotin compounds is to be checked to verify complete derivatization
and extraction. For quantification of tetrabutyltin, use tetrapropyltin (TTPT) as the internal standard.
Derive from the chromatograms, by integration, the peak areas of t
...