EN ISO 17294-1:2024

SLOVENSKI STANDARD
01-julij-2024
Nadomešča:
SIST EN ISO 17294-1:2007
Kakovost vode - Uporaba masne spektrometrije z induktivno sklopljeno plazmo
(ICP-MS) - 1. del: Splošne smernice (ISO 17294-1:2024)
Water quality - Application of inductively coupled plasma mass spectrometry (ICP-MS) -
Part 1: General requirements (ISO 17294-1:2024)
Wasserbeschaffenheit - Anwendung der induktiv gekoppelten Plasma-
Massenspektrometrie (ICP-MS) - Teil 1: Allgemeine Anforderungen (ISO 17294-1:2024)
Qualité de l’eau - Application de la spectrométrie de masse avec plasma à couplage
inductif (ICP- MS) - Partie 1: Exigences générales (ISO 17294-1:2024)
Ta slovenski standard je istoveten z: EN ISO 17294-1:2024
ICS:
13.060.50 Preiskava vode na kemične Examination of water for
snovi chemical substances
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 17294-1
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2024
EUROPÄISCHE NORM
ICS 13.060.50 Supersedes EN ISO 17294-1:2006
English Version
Water quality - Application of inductively coupled plasma
mass spectrometry (ICP-MS) - Part 1: General
requirements (ISO 17294-1:2024)
Qualité de l'eau - Application de la spectrométrie de Wasserbeschaffenheit - Anwendung der induktiv
masse avec plasma à couplage inductif (ICP- MS) - gekoppelten Plasma-Massenspektrometrie (ICP-MS) -
Partie 1: Exigences générales (ISO 17294-1:2024) Teil 1: Allgemeine Anforderungen (ISO 17294-1:2024)
This European Standard was approved by CEN on 20 January 2024.

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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17294-1:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 17294-1:2024) has been prepared by Technical Committee ISO/TC 147 "Water
quality" in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of
which is held by DIN.
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 October 2024, and conflicting national standards shall
be withdrawn at the latest by October 2024.
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 ISO 17294-1:2006.
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 17294-1:2024 has been approved by CEN as EN ISO 17294-1:2024 without any
modification.
International
Standard
ISO 17294-1
Second edition
Water quality — Application of
2024-03
inductively coupled plasma mass
spectrometry (ICP-MS) —
Part 1:
General requirements
Qualité de l’eau — Application de la spectrométrie de masse avec
plasma à couplage inductif (ICP-MS) —
Partie 1: Exigences générales
Reference number
ISO 17294-1:2024(en) © ISO 2024

ISO 17294-1:2024(en)
© ISO 2024
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 17294-1:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus . 4
5.1 General .4
5.2 Sample introduction .4
5.2.1 General .4
5.2.2 Pump .5
5.2.3 Nebulizer .5
5.2.4 Spray chamber .6
5.2.5 Other systems .6
5.3 Torch and plasma .6
5.4 Gas and gas control .7
5.5 Generator .7
5.6 Transfer of the ions to the mass spectrometer .7
5.7 Mass spectrometer .8
5.7.1 General .8
5.7.2 Lens system .8
5.7.3 Collision or reaction cell .8
5.7.4 Analyser .8
5.7.5 Detector .9
5.7.6 Alternative mass spectrometers and types of instruments .10
5.8 Signal processing and instrument control.11
6 Interferences by concomitant elements .11
6.1 General .11
6.2 Spectral interferences .11
6.2.1 General .11
6.2.2 Possible elimination strategies for polyatomic ion interferences . 12
6.3 Non-spectral interferences . 13
6.3.1 General . 13
6.3.2 Interferences in the nebulization process . 13
6.3.3 Interferences in the plasma . 13
6.3.4 Interferences in the interface or lens area .14
6.3.5 Possible elimination strategies for non-spectral interferences (matrix effects) .14
7 Adjustment of the apparatus . 17
7.1 General .17
7.2 Tuning the apparatus .17
7.2.1 General .17
7.2.2 Alignment of the plasma .18
7.2.3 Mass calibration .18
7.2.4 Resolution .18
7.2.5 Detector .18
7.3 V erification of instrument performance criteria .19
8 Preparatory steps . 19
8.1 General .19
8.2 Choice of isotopes . 20
8.3 Choice of instrumental settings . 20
8.4 Choice of integration time .21
8.5 Choice of reference elements — Internal standards . 22

iii
ISO 17294-1:2024(en)
8.6 Linearity and working range . 22
8.7 Composition of calibration solutions . 23
8.8 Method development for cool plasma conditions . 23
8.9 Determination of the method performance . 23
8.9.1 General . 23
8.9.2 Instrument detection limit .24
8.9.3 Method detection limit .24
8.9.4 Precision of the method .24
9 Procedure .24
9.1 General .24
9.2 Calibration .24
9.3 Necessary solutions . 25
9.4 Measurement . 25
Annex A (informative) Spectral interferences, choice of isotopes and instrument detection
limits for quadrupole ICP-MS instruments .27
Bibliography .32

iv
ISO 17294-1:2024(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 document 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 147, Water quality, Subcommittee SC 2, Physical,
chemical and biochemical methods, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 230, Water analysis, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 17294-1:2004), which has been technically
revised.
The main changes are as follows:
— scope has been revised to align with ISO 17294-2;
— text has been revised to reflect currently available instruments used in routine daily practice in many
laboratories;
— Clauses 5 and 6 have been revised to reflect the state-of-the-art equipment used to measure elements
according to ISO 17294-2;
— abbreviated terms in Clause 9 have been revised to align with common terms used in other standards;
— Table A.1 has been updated.
A list of all parts in the ISO 17294 series can be found on the ISO website.
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.

v
ISO 17294-1:2024(en)
Introduction
Since the last edition of this document, new developments in metal analysis with inductively coupled plasma
mass spectrometry (ICP-MS) have taken place. The use of the collision or reaction cell (CRC) technology
in quadrupole ICP-MS and triple quadrupole ICP-MS has increased in laboratories. For this reason, this
document has been revised and new items have been added.
The intention for the revision of this document was to focus on the instrumentation currently available and
in use for determining elements according to ISO 17294-2 in daily practice in laboratories. The consequence
of this starting point is that the use of correction formulae has been moved to Annex A because of its reduced
importance in modern instrumentation. Many principles also apply for high-resolution or accurate mass
instrumentation, although they are not described in detail in this document.

vi
International Standard ISO 17294-1:2024(en)
Water quality — Application of inductively coupled plasma
mass spectrometry (ICP-MS) —
Part 1:
General requirements
1 Scope
This document specifies the principles of inductively coupled plasma mass spectrometry (ICP-MS) and
provides general requirements for the use of this technique to determine elements in water, digests of
sludges and sediments (e.g. digests of water as described in ISO 15587-1 or ISO 15587-2). Generally, the
measurement is carried out in water, but gases, vapours or fine particulate matter can be introduced too.
This document applies to the use of ICP-MS for aqueous solution analysis.
The ultimate determination of the elements is described in a separate International Standard for each series
of elements and matrix. The individual clauses of this document refer the user to these guidelines for the
basic principles of the method and the configuration of the instrument.
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 Guide 33, Reference materials — Good practice in using reference materials
ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General principles
and definitions
ISO 6206, Chemical products for industrial use — Sampling — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO Guide 33, ISO 5725-1, ISO 6206 and
the following apply.
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/
3.1
analyte
element(s) to be determined
3.2
blank calibration solution
solution prepared in the same way as the calibration solution (3.3) but leaving out the analyte (3.1)

ISO 17294-1:2024(en)
3.3
calibration solution
solution used to calibrate the instrument, prepared from a stock solution(s) (3.16) or from a certified
standard
3.4
calibration check solution
solution of known composition within the range of the calibration solution (3.3) but prepared independently
3.5
determination
entire process from preparing the test sample solution (3.18) up to and including the measurement and
calculation of the final result (3.14)
3.6
instrument detection limit
L
DI
smallest concentration that can be detected with a defined statistical probability using a contaminant-free
instrument and a blank calibration solution (3.2)
3.7
linearity
functional relationship between the indicated values and the contents
3.8
calibration verification solution
solution with a known concentration of the matrix components compared to the calibration solutions (3.4),
but having an analyte (3.1) concentration half that of the (highest) calibration solution
3.9
method detection limit
L
DM
smallest analyte (3.1) concentration that can be detected with a specified analytical method with a defined
statistical probability
3.10
net intensity
I
signal obtained after background correction
3.11
optimization solution
solution serving for mass calibration and for the optimization of the apparatus conditions
EXAMPLE Adjustment of maximal sensitivity (3.15) with respect to minimal oxide formation rate and minimal
formation of doubly charged ions.
3.12
precision
closeness of agreement between independent test results (3.14) obtained under prescribed conditions
Note 1 to entry: Precision depends only on the distribution of random errors and does not relate to true value or the
specified value.
[SOURCE: ISO 5725-1:2023, 3.12, modified — the definition has been revised and Notes 2 and 3 to entry have
been removed.]
3.13
reagent blank solution
solution prepared by adding to the solvent the same amounts of reagents as those added to the test sample
solution (3.18) and with the same final volume

ISO 17294-1:2024(en)
3.14
result
outcome of a measurement
Note 1 to entry: The result is typically calculated as mass concentration (U), expressed in milligrams per litre.
3.15
sensitivity
S
ratio of the variation of the magnitude of the signal (ΔI) to the corresponding variation in the concentration
of the analyte (3.1) (ΔC)
Note 1 to entry: Sensitivity is calculated as shown in Formula (1):
ΔI
S= (1)
ΔC
3.16
stock solution
solution with accurately known analyte (3.1) concentration(s), prepared from pure chemicals
Note 1 to entry: Stock solutions are reference materials within the meaning of ISO Guide 30.
Note 2 to entry: Pure chemicals are those which have the highest available purity and known stoichiometry and for
which the content of analyte and contaminants should be known with an established degree of certainty.
3.17
test sample
sample prepared from the laboratory sample
Note 1 to entry: The sample can be prepared, for example, by grinding or homogenizing.
3.18
test sample solution
solution prepared with the fraction (test portion) of the test sample (3.17) according to the appropriate
specifications, such that it can be used for the envisaged measurement
4 Principle
In the present context, a plasma is a small cloud of hot (6 000 K to 10 000 K) and partly ionized (approximately
1 %) argon gas. Cool plasmas have temperatures of only about 2 500 K. The plasma is sustained by a radio-
frequency field. The sample is brought into the plasma as an aerosol. Liquid samples are converted into an
aerosol using a nebulizer. In the plasma, the solvent of the sample evaporates, and the compounds present
decompose into the constituent atoms (dissociation, atomization). The analyte atoms are in most cases
almost completely ionized.
In the mass spectrometer, typically equipped with a collision or reaction cell (CRC) and quadrupole, the
ions are separated and the elements identified according to their mass-to-charge ratio, m/z, while the
concentration of the element is proportional to the number of ions.
ICP-MS is a relative technique. The proportionality factor between response and analyte concentration
relates to the fact that only a fraction of the analyte atoms that are aspirated reach the detector as an ion.
The proportionality factor is determined by measuring calibration solutions (calibration).
With instruments equipped with a magnetic sector field, higher mass resolution spectra can be obtained.
This can help to separate isotopes of interest from interfering species.

ISO 17294-1:2024(en)
5 Apparatus
5.1 General
The principal components of the equipment used for ICP-MS is shown in Figure 1 in the form of a schematic
block diagram.
Figure 1 — Schematic block diagram of an ICP-MS instrument
5.2 Sample introduction
5.2.1 General
To introduce solutions to be measured into the plasma, a peristaltic pump, a nebulizer and a spray chamber
are generally used. The pump supplies the solution to the nebulizer. In the nebulizer, the solution is converted
into an aerosol by an (argon) gas flow, except when an ultrasonic nebulizer is used; see 5.2.3. Large drops
are removed from the aerosol in the spray chamber by means of collisions with the walls or other parts of
the chamber and they are drained off as liquid. The resulting aerosol is then transferred into the plasma via
the injector tube of the torch (see 5.3) with the help of the nebulizer gas (sample-introduction gas).
The sample introduction system is designed in such a way that:
a) the average mass per aerosol droplet is as low as possible;
b) the mass of the aerosol transported to the plasma in each period of time is as constant as possible;
c) the droplet size distribution and the added mass of the aerosol in each period of time is, as far as possible,
independent of the solution to be measured (matrix effect, see 6.3);
d) the time the aerosol takes to stabilize after introduction in the spray chamber of a solution is as short as
possible;
e) the parts of the system in contact with the sample or the aerosol are not corroded, degraded
or contaminated by the solution;
f) carry-over from one sample to subsequent samples is minimized.
The components of the sample introduction system shall be able to withstand any corrosive substances in
the solutions, such as strong acids. The material used for pump tubing should be resistant to dissolution and
chemical attack by the solution to be nebulized. Components that come into contact with the solution are
often made of special plastics. The use of glass and quartz shall be avoided if hydrofluoric acid is present
in the test solution. In those cases, the nebulizer, spray chamber and torch injector tube shall be made of
suitable inert materials.
ISO 17294-1:2024(en)
The various components of the sample introduction system are discussed hereafter in relation to these
requirements and some examples are compared.
5.2.2 Pump
The use of a peristaltic pump to feed the solutions [e.g. sample, reference elements solutions (8.5)] to the
nebulizer is not necessary with some nebulizers (see 5.2.3) but is desirable in almost all cases in order to
render the supply of the solution less dependent on the composition of the solution. A sampling pump is used
on all modern instruments.
It is advisable to use a peristaltic pump having the largest possible number of rollers and a velocity as high
as possible to avoid major surges in the supply of the solution. The quantity of solution that is pumped is
mostly between 0,1 ml/min and 1,0 ml/min and typically around 0,4 ml/min to 0,5 ml/min.
5.2.3 Nebulizer
1)
The most common nebulizers are the concentric nebulizer (e.g. Meinhard ), the crossflow nebulizer, the
V-groove nebulizer and the ultrasonic nebulizer (USN). The first one can be used in self-aspiration mode and
the crossflow nebulizer can be used without a pump (but seldom are). Nebulizers (except for the USN) can be
made of glass or of hard, inert plastic such as PFA.
The concentric nebulizer consists of two concentric tubes, the outer one being narrowed at the end. The
solution flows through the central tube and the nebulizer gas (see 5.4) through the tube around it, creating
a region of lower pressure around the tip of the central tube and disrupting the solution flow into small
droplets (the aerosol). This nebulizer performs best with solutions with a low content of dissolved matter,
although there are also models that are less sensitive to significant amounts of dissolved matter in the
solution to be nebulized.
The crossflow nebulizer consists of two capillary tubes mounted at a right angle, one being used for the
supply of the solution and the other for the supply of the nebulizer gas. Depending on the distance between
the openings of the capillary tubes and their diameters, the nebulizer can be self-aspirating. With larger
diameters, the chance of blockages occurring is of course smaller, but a pump shall be used to supply the
solution.
In the V-groove nebulizer, the solution flows through a vertical V-groove to the outflow opening of the
nebulizer gas. The solution is nebulized by the high linear speed of this gas at the very small diameter outflow
opening. The V-groove nebulizer was developed for solutions with a high concentration of dissolved matter
and/or with suspended particles, although it is also used successfully with diluted and/or homogenous
2)
solutions. Similar nebulizers are the Burgener nebulizer and the cone-spray nebulizer, with similar outer
shapes as the concentric nebulizer. With these nebulizers, the solution flows out into a cone-shaped area at
the tip of the nebulizer instead of a V-groove and flows over the outflow opening of the nebulizer gas.
In the ultrasonic nebulizer, the solution is pumped through a tube that ends near the transducer plate that
vibrates at an ultrasonic frequency. The amount of aerosol produced (the efficiency) is typically 10 % to 20 %
of the quantity of the pumped solution. This is so high that the aerosol shall be dried (desolvated) before being
introduced into the plasma, which would otherwise be extinguished. The aerosol is transported to the plasma
by the nebulizer gas. Disadvantages of the ultrasonic nebulizer include its greater susceptibility to matrix
effects, diminished tolerance to high dissolved solid contents and a longer rinsing time (i.e. Ag, B, Hg, Mo).
For the other nebulizers previously described, the efficiency is typically only a few per cent. The efficiency
increases when the solution introduction rate is decreased. Specially designed concentric micro-nebulizers
made of special types of hard plastic operate at solution flow rates of 10 µl/min to 100 µl/min and efficiencies
1) The Meinhard nebulizer is an example of a suitable product available commercially. This information is given for
the convenience of users of this document and does not constitute an endorsement by ISO of this product. Equivalent
products may be used if they can be shown to lead to the same results.
2) The Burgener nebulizer is an example of a suitable product available commercially. This information is given for
the convenience of users of this document and does not constitute an endorsement by ISO of this product. Equivalent
products may be used if they can be shown to lead to the same results.

ISO 17294-1:2024(en)
approaching 100 %. These concentric micro-nebulizers often show a very good precision (low coefficient of
variation of the signal) and can also be combined with a membrane desolvator [see 6.2.1, a)].
Several other types of nebulizers may be used for specific applications.
5.2.4 Spray chamber
In the spray chamber [e.g. Scott (double concentric tubes), cyclonic or impact bead], the larger drops of the
aerosol are drained off in liquid form. To create and keep over-pressure in the chamber, the liquid shall be
removed via a sealed drain tube utilizing hydrostatic pressure or by pumping. The internal diameter of the
drain tubing should be higher than that of the sample uptake tubing to ensure that no liquid remains in the
spray chamber. The liquid shall be removed evenly to avoid pressure variations in the chamber, which can
result in variations in the signal.
By cooling the spray chamber to 2 °C to 5 °C, the water vapour formed in the nebulization process condenses,
thereby reducing the water load of the plasma. This results in a reduction in the formation of interfering
polyatomic ions (oxides); see 6.2.2.
5.2.5 Other systems
There are other types of introduction systems for particular applications. These include laser or spark
ablation of a solid sample, evaporation of the solution by means of a graphite furnace or a metal filament,
introduction of a gas or a gas form of the analyte (as in the hydride generation technique), systems for the
direct introduction of solid matter into the plasma (e.g. in the form of a slurry of a finely dispersed powder in
a solvent) and the introduction with a graphite rod directly into the plasma.
With the direct injection nebulizer (DIN), a pneumatic concentric micro-nebulizer, instead of the inner tube
(injector; see 5.3), is placed in the torch. It has a sample introduction efficiency of almost 100 %, with a
sample uptake rate of typically 10 µl/min. A DIN can be used for techniques giving transient signals (e.g.
coupling to chromatographic or flow injection devices) and for minimizing the memory effects of, for
instance, silver, boron, molybdenum and mercury. These systems are not discussed in this document.
5.3 Torch and plasma
The torch consists of three concentric tubes and can be designed as a monoblock or demountable unit. Quartz
is the material generally used, but also high purity ceramic torches are available. Sometimes the innermost
tube (the sample introduction tube or injector tube) is made of inert material, for example aluminium oxide
or sapphire. It usually ends at 4 mm to 5 mm before the first winding of the coil. The aerosol produced in the
sample introduction system flows through the sample introduction tube, transported by an (argon) gas flow
(the nebulizer gas) with a flow rate of approximately 0,5 l/min to 1,5 l/min.
The auxiliary gas flows between the sample introduction tube and the middle tube with a flow rate of up to
3 l/min. Whether or not an auxiliary gas or humidification of the argon flow is used depends on, for example,
the type of device concerned, the solvent used and the salt concentration. The function of the auxiliary gas
is to increase the separation of the plasma and the torch and thus reduce the temperature at the end of the
injector (and intermediate) tube. This avoids deposits of dissolved material or the build-up of carbon (when
organic solvents are nebulized) on the injector tube.
The plasma gas flows between the middle and outermost tubes with a flow rate of 12 l/min to 20 l/min. The
function of the plasma gas is to maintain the plasma and to cool the outer tube of the torch.
Around the top of the torch, there is a cooled coil with two to five windings. A high-frequency current flows
through the coil and excites the plasma (see 5.5).
The torch is generally placed in a separate metal compartment. This compartment shall be connected to
an exhaust system (extraction) because of the production of heat and harmful gases (including ozone). The
metal of the compartment protects the users and the instrument (electronics) against the high-frequency
radiation, which is released from the coil, and against the ultraviolet radiation emitted by the plasma. A
camera, a lens or a special window, covered with a darkened glass to protect the observer's eyes from the

ISO 17294-1:2024(en)
intense plasma emission radiation, allows visual observation of the plasma. Some systems provide a camera
monitor for the purpose of viewing the plasma area.
A grounded metal shield (shield torch) can be placed between the coil and the torch to reduce the levels
of argon-based (poly)atomic ions (see 6.2) that interfere particularly with the determination of K, Ca and
Fe. Cold plasma conditions (relatively low plasma power and high nebulizer gas flow rate) can, in cases
of matrices with low matter content, also be used to optimize the reduction of argon based polyatomic
interferences. Similar performance can be obtained by a torch system which uses a balanced radiofrequency
(RF) drive, avoiding the requirement for the grounded metal shield and allowing easier removal of the torch
for maintenance.
5.4 Gas and gas control
In virtually every instrument, argon is used as nebulizer gas (sample introduction gas), auxiliary gas and
plasma gas. Argon gas with a purity of greater than 99,995 % is preferred. Exact amounts of oxygen can
be added to the nebulizer or auxiliary gas to avoid carbon build-up on the sampling cone and torch injector
when analysing solutions made with organic solvents. The additions of too much oxygen result in the
burning away of the graphite carbon that deposits on the sampling cone (see also 5.6). Mixtures of argon
an
...