SIST EN ISO 16965:2026

SLOVENSKI STANDARD
01-marec-2026
Nadomešča:
SIST EN 16171:2017
SIST-TS ISO/TS 16965:2019
Trdni matriksi v okolju - Določanje elementov z masno spektrometrijo z induktivno
sklopljeno plazmo (ICP-MS) (ISO 16965:2025)
Environmental solid matrices - Determination of elements using inductively coupled
plasma mass spectrometry (ICP-MS) (ISO 16965:2025)
Feststoffe in der Umwelt - Bestimmung von Elementen mittels Massenspektrometrie mit
induktiv gekoppeltem Plasma (ICP-MS) (ISO 16965:2025)
Matrices solides environnementales - Détermination des éléments par spectrométrie de
masse avec plasma à couplage inductif (ICP (ISO 16965:2025)
Ta slovenski standard je istoveten z: EN ISO 16965:2025
ICS:
13.030.20 Tekoči odpadki. Blato Liquid wastes. Sludge
13.080.10 Kemijske značilnosti tal 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.

EN ISO 16965
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2025
EUROPÄISCHE NORM
ICS 13.030.01; 13.080.10 Supersedes EN 16171:2016
English Version
Environmental solid matrices - Determination of elements
using inductively coupled plasma mass spectrometry (ICP-
MS) (ISO 16965:2025)
Matrices solides environnementales - Détermination Feststoffe in der Umwelt - Bestimmung von Elementen
des éléments par spectrométrie de masse avec plasma mittels Massenspektrometrie mit induktiv
à couplage inductif (ICP (ISO 16965:2025) gekoppeltem Plasma (ICP-MS) (ISO 16965:2025)
This European Standard was approved by CEN on 22 September 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16965:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 16965:2025) has been prepared by Technical Committee ISO/TC 190 "Soil
quality " in collaboration with Technical Committee CEN/TC 444 “Environmental characterization of
solid matrices” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2026, and conflicting national standards shall
be withdrawn at the latest by March 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 16171:2016.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 16965:2025 has been approved by CEN as EN ISO 16965:2025 without any modification.

International
Standard
ISO 16965
First edition
Environmental solid matrices —
2025-09
Determination of elements using
inductively coupled plasma mass
spectrometry (ICP-MS)
Matrices solides environnementales — Détermination des
éléments par spectrométrie de masse avec plasma à couplage
inductif (ICP-MS)
Reference number
ISO 16965:2025(en) © ISO 2025
ISO 16965:2025(en)
© ISO 2025
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
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 16965:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Interferences . 2
5.1 General .2
5.2 Spectral interferences .2
5.2.1 Isobaric elemental interferences .2
5.2.2 Isobaric molecular interferences and doubly-charged ion interferences .2
5.2.3 Non-spectral interferences .3
6 Reagents . 3
7 Apparatus . 6
7.1 General requirements .6
7.2 Mass spectrometer .6
7.3 Mass-flow controller .6
7.4 Nebuliser with variable speed peristaltic pump .6
7.5 Gas supply .7
7.6 Storage bottles for the stock, standard, calibration and sample solutions .7
8 Procedure . 7
8.1 Test sample solution .7
8.2 Test solution .7
8.3 Instrument set-up .7
8.4 Calibration .8
8.4.1 Linear calibration function .8
8.4.2 Standard addition calibration .8
8.4.3 Determination of correction factors .8
8.4.4 Variable isotope ratio .8
8.5 Sample measurement .8
9 Calculation . 9
10 Expression of results . 9
11 Performance characteristics . 10
11.1 Blank .10
11.2 Calibration check .10
11.3 Internal standard response .10
11.4 Interference .10
11.5 Recovery .10
11.6 Performance data .10
12 Test report .11
Annex A (informative) Performance data .12
Annex B (informative) Selected isotopes and spectral interferences for quadrupole ICP-MS
instruments .18
Bibliography . 19

iii
ISO 16965:2025(en)
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 190, Soil quality, Subcommittee SC 3, Chemical
and physical characterization, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 444, Environmental characterization of solid matrices, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This first edition of ISO 16965 cancels and replaces ISO/TS 16965:2013, which has been technically revised.
The main changes are as follows :
— the contents of ISO/TS 16965 and EN 16171 have been merged;
— the scope has been expanded to include treated biowaste, waste, sludge and sediment;
— performance data from an interlaboratory comparison has been added (Annex A).
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.

iv
International Standard ISO 16965:2025(en)
Environmental solid matrices — Determination of elements
using inductively coupled plasma mass spectrometry (ICP-MS)
WARNING — Persons using this document should be familiar with usual 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 — Tests conducted according to this document shall be carried out by suitably trained staff.
1 Scope
This document specifies a method for the determination of the following elements in aqua regia, nitric acid
or mixture of hydrochloric (HCl), nitric (HNO ) and tetrafluoroboric (HBF )/hydrofluoric (HF) acid digests
3 4
of soil, treated biowaste, waste, sludge and sediment:
aluminium (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), bismuth (Bi), boron (B),
cadmium (Cd), calcium (Ca), cerium (Ce), caesium (Cs), chromium (Cr), cobalt (Co), copper (Cu),
dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), gallium (Ga), germanium (Ge), gold (Au),
hafnium (Hf), holmium (Ho), indium (In), iridium (Ir), iron (Fe), lanthanum (La), lead (Pb), lithium (Li),
lutetium (Lu), magnesium (Mg), manganese (Mn), mercury (Hg), molybdenum (Mo), neodymium (Nd),
nickel (Ni), palladium (Pd), phosphorus (P), platinum (Pt), potassium (K), praseodymium (Pr), rhenium (Re),
rhodium (Rh), rubidium (Rb), ruthenium (Ru), samarium (Sm), scandium (Sc), selenium (Se), silicon (Si),
silver (Ag), sodium (Na), strontium (Sr), sulfur (S), tellurium (Te), terbium (Tb), thallium (Tl), thorium (Th),
thulium (Tm), tin (Sn), titanium (Ti), tungsten (W), uranium (U), vanadium (V), ytterbium (Yb), yttrium (Y),
zinc (Zn), and zirconium (Zr).
NOTE 1 Details on validation are given in Annex A.
This method is also applicable for the determination of major, minor and trace elements in aqua regia and
[7]
nitric acid digests and in eluates of construction products (EN 17200 ).
NOTE 2 Construction products include e.g. mineral-based products, bituminous products, metals, wood-based
products, plastics and rubbers, sealants and adhesives, paints and coatings.
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 17294-1, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-MS) — Part 1:
General requirements
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/

ISO 16965:2025(en)
4 Principle
[5]
Digests of soil, treated biowaste, waste, sludge and sediments with nitric acid, aqua regia (see EN 16173 ,
[1]
and ISO 54321 ) or hydrochloric (HCl), nitric (HNO ) and tetrafluoroboric (HBF ) or hydrofluoric (HF) acid
3 4
[2]
mixture (EN 13656) , are analysed by ICP-MS to obtain a multi-elemental determination of analytes.
The method measures ions produced by a radiofrequency inductively coupled plasma. Analyte species
originating in the digest solution are nebulised and the resulting aerosol is transported by argon gas into
the plasma. The ions produced by the high temperatures of the plasma are entrained in the plasma gas and
introduced, by means of an interface, into a mass spectrometer, sorted according to their mass-to-charge
ratios and quantified with a detector (e.g. channel electron multiplier).
[1] [2]
NOTE 1 For the determination of tin, only aqua regia extraction applies (e.g. ISO 54321 , EN 13656 ).
NOTE 2 When tetrafluoroboric (HBF ) is used in the acid mixture, boron cannot be determined.
The working range depends on the matrix and the interferences encountered.
The method detection limit of the method is between 0,1 mg/kg dry matter and 2,0 mg/kg dry matter
for most elements. The limit of detection will be higher in cases where the determination is likely to be
interfered (see Clause 5) or in case of memory effects (see e.g. ISO 17294-1).
The method has been validated for the elements given in Table A.2 (sludge), Table A.3 (compost) and
Table A.4 (soil).
5 Interferences
5.1 General
Interferences shall be assessed, and valid corrections applied. Interference correction shall include compensation
for background ions contributed by the plasma gas, reagents, and constituents of the sample matrix.
Detailed information on spectral and non-spectral interferences is given in ISO 17294-1.
5.2 Spectral interferences
5.2.1 Isobaric elemental interferences
Isobaric elemental interferences are caused by isotopes of different elements of closely matched nominal
mass-to-charge ratio and which cannot be separated due to an insufficient resolution of the mass
114 114
spectrometer in use (e.g. Cd and Sn).
Element interferences from isobars can be corrected by considering the influence from the interfering
element (see ISO 17294-1). The isotopes used for correction shall be free of interference. Correction options
are often included in the software supplied with the instrument. Common isobaric interferences are given in
Annex B, Table B.1.
5.2.2 Isobaric molecular interferences and doubly-charged ion interferences
Isobaric molecular interferences and doubly-charged ion interferences in ICP-MS are caused by ions
40 35 + 40 35 +
consisting of more than one atom or charge, respectively. Examples include Ar Cl and Ca Cl ion on
75 98 16 + 114 +
the As signal or Mo O ions on the Cd signal. Natural isotope abundances are available from the
literature.
The accuracy of correction equations is based upon the constancy of the observed isotopic ratios for the
interfering species. Corrections that presume a constant fraction of a molecular ion relative to the “parent”
ion have not been found to be reliable, e.g. oxide levels can vary with operating conditions. If a correction for
an oxide ion is based upon the ratio of parent-to-oxide ion intensities, this shall be determined by measuring

ISO 16965:2025(en)
the interference solution just before the sequence is started. The validity of the correction coefficient should
be checked at regular intervals within a sequence.
Another possibility to remove isobaric molecular interferences is the use of an instrument with collision/
reaction cell technology and further extended to triple quadrupole technology facilitating an even more
effective use of reactive gases for interference removal. The use of high resolution ICP-MS allows the
resolution of these interferences and additionally double-charged ion interferences.
The response of the analyte of interest shall be corrected for the contribution of isobaric molecular
interferences and doubly charged interferences if their impact can be higher than three times the detection
limit or higher than half the lowest concentration to be reported.
More information about the use of correction factors is given in ISO 17294-1.
5.2.3 Non-spectral interferences
Physical interferences are associated with sample nebulisation and transport processes as well as with
ion-transmission efficiencies. Nebulisation and transport processes can be affected if a matrix component
causes a change in surface tension or viscosity. Changes in matrix composition can cause significant signal
suppression or enhancement. Solids can be deposited on the nebuliser tip of a pneumatic nebuliser and on
the cones.
A low level of total dissolved solids should be kept, to minimise deposition of solids in the sample introduction
system of the plasma torch. An internal standard can be used to correct for physical interferences if it is
carefully matched to the analyte, so that the two elements are similarly affected by matrix changes. Other
possibilities to minimise non-spectral interferences are matrix matching, particularly matching of the acid
concentration, and standard addition.
When intolerable physical interferences are present in a sample, a significant suppression of the internal
standard signals will be observed. The relative response of the internal standard in all solutions shall be
±30 % of the internal standard in the preceding blank or continuous calibration verification (CCV) solution
(11.3). Dilution of the sample (e.g. fivefold) usually eliminates the problem.
6 Reagents
For the determination of elements at trace and ultra-trace level, the reagents shall be of adequate purity. The
concentration of the analyte or interfering substances in the reagents and the water should be negligible
compared to the lowest concentration to be determined.
−1
6.1 Water, with an electrical conductivity less than 0,1 mS · m (equivalent to resistivity greater than
0,01 MΩ m at 25 °C). The water used should be obtained from a purification system that delivers ultrapure
water having a resistivity greater than 0,18 MΩ · m (usually expressed by manufacturers of water
purification systems as 18 MΩ · cm).
6.2 Nitric acid, HNO , c(HNO ) approximately 15 mol/l, w(HNO ) approximately mass fraction of 65 %
3 3 3
to 70 %.
6.3 Hydrochloric acid, HCl, c(HCl) approximately 12 mol/l, w(HCl) approximately mass fraction of 35 %
to 37 %.
6.4 Tetrafluoroboric acid (HBF ), c(HBF ) approximately 6 mol/l, w(HBF ) approximately mass fraction
4 4 4
of 38 % to 48 %.
6.5 Hydrofluoric acid (HF), c(HF) approximately 23 mol/l, w(HF) approximately mass fraction of 40 %
to 45 %.
6.6 Boric acid (B(OH) ), solid.
ISO 16965:2025(en)
6.7 Boric acid (B(OH) ) solution, e.g. 4 % (mass fraction) solution.
Dissolve 40 g of boric acid (6.6) in 1 l of water (6.1).
6.8 Single-element standard stock solutions.
Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, In, Ir, K, La, Li, Lu, Mg,
Mn, Mo, Na, Nd, Ni, P, Pb, Pd, Pr, Pt, Rb, Re, Rh, Ru, S, Sb, Sc, Se, Si, Sm, Sn, Sr, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb,
Zn, Zr, (concentration of element) 10 mg/l to 10 000 mg/l each.
Preferably, nitric acid preservation should be applied in order to minimise interferences by chloropolyatomic
molecules. For the preservation of Bi, Hf, Hg, Mo, Sn, Sb, Te, W and Zr, hydrochloric acid can be needed. For
the stabilisation of some elements, e.g. Sb, the addition of hydrofluoric acid can be needed.
Both single-element standard stock solutions and multi-element standard stock solutions with adequate
specification stating the acid used and the preparation technique are commercially available.
These solutions are considered to be stable for more than one year, but in reference to guaranteed stability,
the recommendations of the manufacturer should be considered.
6.9 Anion standard stock solutions.
− 3− 2−
Cl , PO , SO , (concentration of anion) = 1 000 mg/l each.
4 4
Prepare these solutions from the respective acids. The solutions are commercially available.
These solutions are considered to be stable for more than one year, but in reference to guaranteed stability,
the recommendations of the manufacturer should be considered.
6.10 Multi-element standard stock solutions.
Depending on the analytes to be determined, different multi-element standard stock solutions can be
necessary. In general, when combining multi-element standard stock solutions, their chemical compatibility
and the possible hydrolysis of the components shall be regarded. Care shall be taken to prevent chemical
reactions (e.g. precipitation).
The multi-element standard stock solutions are considered to be stable for several months if stored in
the dark. This does not apply to multi-element standard stock solutions that are prone to hydrolysis, in
particular solutions of e.g. Bi, Mo, Sn, Sb, Te, W, Hf and Zr.
Mercury standard stock solutions can be stabilised by adding 1 mg/l Au in nitric acid (6.2) or by adding
hydrochloric acid (6.3) up to 0,6 % (volume fraction).
Multi-element standard stock solutions with more elements are allowed, provided that these solutions are
stable and that the recommendations of the manufacturer are considered.
The following examples of multi-element standard stock solutions can be considered:
— Multi-element standard stock solution at the mg/l level in nitric acid containing the following elements:
Ag, Al, As, B, Ba, Be, Bi, Cd, Ce, Co, Cr, Cu, Fe, Hg, Li, Mn, Nd, Ni, Pb, Pr, Sc, Se, Si, Sm, Sr, Te, Th, Ti, Tl, U, V, Zn.
— Multi-element standard stock solution at the mg/l level in hydrochloric acid containing the following
elements: Mo, Sb, Si, Sn, W, Zr.
— Multi-element standard stock solution at the mg/l level in nitric acid containing the following elements:
Ca, Mg, Na, K, P, S.
6.11 Multi-element calibration solutions.
Prepare in one or more steps calibration solutions at the highest concentration of interest. If more
concentration levels are needed, prepare those similarly.

ISO 16965:2025(en)
Add acids (6.2, 6.3, 6.4, 6.5 and/or 6.7) to match the acid concentration of samples closely.
If traceability of the values is not established, check the validity by comparison with a (traceable) independent
standard.
Check the stability of the calibration solutions.
6.12 Internal standard solution.
Internal standards can either be added to every flask or added online. It is essential that the same
concentration of internal standard is added to all measurement solutions. The following elements are among
the most often used: Li (isotopically-enriched isotope), Be, Sc, Ga, Ge, Y, Rh, In, Cs, Pr, Tb, Ho, Re, Ir, Bi, and Th.
The choice of elements for the internal standard solution depends on the analytical problem. The solution
of this/these internal standard(s) should cover the mass range of interest. The internal standards elements
shall not be analytes and the concentrations of the selected elements should be negligibly low in the digests
of samples.
Generally, a suitable final concentration of the internal standard in samples and calibration solutions is
1 µg/l to 50 µg/l (for a high and stable count rate). The use of a collision/reaction cell can require higher
concentrations.
For the determination of mercury (Hg), it is recommended to add a gold (Au) solution in diluted HCl to the
internal standard solution to allow a final concentration of at least 50 µg/l in the solution to be measured
[(concentration Au) ≥ 50 µg/l]. Alternatively, if Au needs to be determined, a KBrO solution in diluted HCl
can be added to the internal standard solution to allow a final concentration of at least 0,009 mmol/l KBrO
in the solution to be measured.
6.13 Calibration blank solution.
Prepare the calibration blank solution by diluting acids (6.2, 6.3, 6.4, 6.5 and/or 6.7) with water (6.1) to the
same concentrations as used in the calibration solutions and test solutions.
6.14 Test blank solution.
The test blank solution shall contain all of the reagents in the same concentrations and shall be handled
in the same way throughout the procedure as the samples. The test blank solution contains the same acid
concentration in the final solution as the test solution after the digestion method is applied.
6.15 Optimisation solution.
The optimisation solution is used for mass calibration and for optimisation of the instrumental settings, e.g.
adjustment of maximal sensitivity with respect to minimal oxide formation rate and minimal formation of
doubly charged ions. It should contain elements covering the total mass range, as well as elements prone to
a high oxide formation rate or to the formation of doubly charged ions. The composition of the optimisation
solution depends on the elements of interest, instrument and manufacturer’s instructions. An optimisation
solution containing e.g. Mg, Cu, Rh, In, Ba, La, Ce, U and Pb is suitable. Li, Be and Bi are less suitable because
they tend to cause memory effects at higher concentrations.
The mass concentrations of the elements used for optimisation should allow count rates of more than
10 counts per second.
6.16 Interference check solution.
The interference check solutions are used to determine the corresponding factors for the correction
equations. High demands are made concerning the purity of the basic reagents due to the high mass
concentrations.
Interference check solutions shall contain all the interferences of practical relevance given in ISO 17294-1, at
a concentration level at the same range as expected in the samples (see also 11.4).

ISO 16965:2025(en)
Leaving out an interfering element according to ISO 17294-1 is permitted if it can be demonstrated that its
impact is negligible and lasting.
In unusual situations, the other interfering elements according to ISO 17294-1 shall also be investigated for
relevance.
EXAMPLE An example of the composition of an interference check solution is:
− 3− 2−
ρ(Ca) = 2 500 mg/l; ρ(Cl ) = 2 000 mg/l; ρ(PO ) = 500 mg/l and ρ(SO ) = 500 mg/l
4 4
and for digests also
ρ(C) = 1 000 mg/l; ρ(Fe) = 500 mg/l; ρ(Na) = 500 mg/l and ρ(Al) = 500 mg/l.
7 Apparatus
7.1 General requirements
The stability of samples, measuring, and calibration solutions depends to a high degree on the container
material. For the determination of elements in a very low concentration range (< 1 µg/kg), glass or polyvinyl
chloride (PVC) should not be used. Instead, perfluoroalkoxy alkane (PFA), hexafluoroethene propene (FEP)
or quartz containers, cleaned with diluted, high quality nitric acid or hot, concentrated nitric acid in a closed
system should be used. For the determination of elements in a higher concentration range, containers made
from high density polyethylene (HDPE) or polytetrafluoroethene (PTFE) are also suited for the collection of
samples.
The limit of detection of most elements is affected by contamination of solutions and this depends
predominantly on the cleanliness of laboratory air.
The use of piston pipettes is permitted and enables the preparation of smaller volumes of calibration
solutions. The application of dilutors is also allowed. Every charge of pipette tips and single-use plastics
vessels shall be tested for impurities.
For more detailed information on the instrumentation see ISO 17294-1.
7.2 Mass spectrometer
A mass spectrometer with inductively coupled plasma (ICP) suitable for multi-element and isotope analysis
is required. The spectrometer should be capable of scanning a mass range from 5 m/z (amu) to 240 m/z (amu)
with a resolution of at least 1 m/z peak width at 5 % of peak height (m = mass number; z = charge number).
The instrument may be fitted with a conventional or extended dynamic range detection system.
Quadrupole ICP-MS, collision/reaction cell ICP-MS, triple quadrupole ICP-MS, high-resolution ICP-MS and
time-of-flight ICP-MS instrumentation are suitable for measurement.
7.3 Mass-flow controller
A mass-flow controller on the nebuliser gas supply is strongly recommended. Mass-flow controllers for the
plasma gas and the auxiliary gas are preferred. A cooled spray chamber (cold water or Peltier element) can
be beneficial in reducing some types of interferences (e.g. from polyatomic oxide species).
7.4 Nebuliser with variable speed peristaltic pump
The speed of the pump and the number of rolls shall be sufficient to provide a stable signal. The quantity of
solution that is pumped is mostly between 0,1 ml and 1,0 ml per minute and typically around 0,4 ml to 0,5 ml
per minute.
ISO 16965:2025(en)
7.5 Gas supply
7.5.1 Argon, Ar, with purity better than 99,99 % (volume fraction).
7.5.2 Reaction gas, e.g. helium (He), hydrogen (H ), oxygen (O ), ammonia gas (NH ), or methane (CH )
2 2 3 4
with high purity grade, i.e. > 99,99 % (volume fraction).
7.6 Storage bottles for the stock, standard, calibration and sample solutions
Preferably made from perfluoroalkoxy alkane (PFA) or hexafluoroethene propene (FEP). For the
determination of elements in a higher concentration range (> 1 µg/kg), high density polyethylene (HDPE) or
polytetrafluoroethene (PTFE) bottles can be suitable.
8 Procedure
8.1 Test sample solution
[5]
The test sample solution is a particle-free digest or extraction solution prepared according to e.g. EN 16173 ,
[2] [1]
EN 13656 , or ISO 54321 .
8.2 Test solution
The test solution is an aliquot of the test sample solution and can be directly obtained from the test sample
solution or can be diluted to accommodate the measurement range or to dilute the matrix.
The acidity of calibration solutions shall match the acid concentration in test solutions.
Ensure that all elements are present in a non-volatile form. Volatile species shall be converted to non-volatile
ones, e.g. sulfide oxidation by hydrogen peroxide.
8.3 Instrument set-up
Adjust the instrumental parameters of the ICP-MS system in accordance with the manufacturer’s
instructions. A guideline for method and instrument set up is given in ISO 17294-1.
Specify the isotopes and the need for corresponding corrections (see Annex B). See ISO 17294-1, for a method
to determine these factors. Alternatively, apply multivariate calibration procedures.
Specify the rinsing times depending on the length of the flow path; in the case of wide working range of
analyte mass concentrations in the test solutions, allow longer rinsing periods.
The use of an internal standard is mandatory. Add the internal standard solution (6.12) to the interference
check solution (6.16), to all multi-element calibration solutions (6.11), to the calibration blank solutions
(6.13), and to all test solutions.
NOTE 1 Online dilution and mixing of the sample flow with internal standard solution by means of the peristaltic
pump of the nebuliser is commonly used. In such cases, the calibration solutions are diluted the same way as the
sample solutions.
The mass concentration of the internal standard elements shall be the same in all solutions. Generally, a
suitable concentration of the internal standard element in sample and calibration solutions is 10 µg/l to
50 µg/l (for a high and stable count rate, at least 50 000 counts/s to 100 000 counts/s).
Adjust the instrument to working condition. This takes usually 30 min.
Before each series of measurements check the sensitivity and the stability of the system and minimise
interferences, e.g. by using the optimisation solution (6.15).

ISO 16965:2025(en)
Check the resolution and the mass calibration as often as required by the manufacturer.
NOTE 2 ICP-MS has excellent multi-element capability. Nevertheless, it does not mean that all elements can be
analysed under optimal conditions during one measurement run. The sensitivity of determination depends on
numerous parameters (nebuliser flow, radio-frequency power, lens voltage, lens voltage mode, etc.).
8.4 Calibration
8.4.1 Linear calibration function
ICP-MS provides a large linear measurement range. The linearity over a broad concentration range shall
be checked for setting the calibration range. Satisfying results are obtained with a two-point calibration: a
blank calibration solution and a calibration solution for the upper point of the measurement range. However,
multiple calibration solutions (a minimum of four calibration standards plus a blank calibration) are
recommended in case of a more orders of magnitude measurement range. The calibration function is only
valid under specific operational conditions and should be re-established if these conditions are changed.
After the failure of a control sample it is sufficient to recalibrate with minimum 2 points and perform a
calibration check (11.2).
Multi-level calibration and standard least-squares fitting can lead to wrong results because of the
inhomogeneity of the variances of the measurements of the calibration solutions over the concentration
range. This approach leads to errors at the low end of the calibration curve, unless weighed linear regression
is used instead of the standard least-squares fitting. Weighed linear regression is based on the principle that
the weighing factor is inversely proportional to the standard deviation of the measurement of the calibration
solution.
8.4.2 Standard addition calibration
Add a known amount of standard solution of the analyte and an equal amount of blank solution to two
separate but equal portions of the test solution (or its dilution). Minimise dilution or correct for spike
dilution. The added amount of standard solution should be between 0,4 times and 2 times the expected
sample mass concentration. Measure both solutions as a sample solution. Determine the ‘measured spike
concentration’ as the difference in mass concentration between the two spiked sample portions. Use the
ratio ‘true spike concentration’ versus ‘measured spike concentration’ as a correction factor for the initially
measured concentra
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