oSIST prEN ISO 6143:2023

SLOVENSKI STANDARD
oSIST prEN ISO 6143:2023
01-september-2023
Analiza plinov - Primerjalne metode za določevanje in preverjanje sestave
kalibrirnih plinskih zmesi (ISO/DIS 6143:2023)
Gas analysis - Comparison methods for determining and checking the composition of
calibration gas mixtures (ISO/DIS 6143:2023)
Gasanalyse - Vergleichsverfahren zur Bestimmung und Überprüfung der
Zusammensetzung von Kalibriergasgemischen (ISO/DIS 6143:2023)
Analyse des gaz - Méthodes de comparaison pour la détermination et la vérification de la
composition des mélanges de gaz d’étalonnage (ISO/DIS 6143:2023)
Ta slovenski standard je istoveten z: prEN ISO 6143
ICS:
71.040.40 Kemijska analiza Chemical analysis
oSIST prEN ISO 6143:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 6143:2023

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oSIST prEN ISO 6143:2023
DRAFT INTERNATIONAL STANDARD
ISO/DIS 6143
ISO/TC 158 Secretariat: SAC
Voting begins on: Voting terminates on:
2023-07-31 2023-10-23
Gas analysis — Comparison methods for determining and
checking the composition of calibration gas mixtures
Analyse des gaz — Méthodes comparatives pour la détermination et la vérification de la composition des
mélanges de gaz pour étalonnage
ICS: 71.040.40
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
DRAFT INTERNATIONAL STANDARD
ISO/DIS 6143
ISO/TC 158 Secretariat: SAC
Voting begins on: Voting terminates on:

Gas analysis — Comparison methods for determining and
checking the composition of calibration gas mixtures
Analyse des gaz — Méthodes comparatives pour la détermination et la vérification de la composition des
mélanges de gaz pour étalonnage
ICS: 71.040.40
This document is circulated as received from the committee secretariat.
COPYRIGHT PROTECTED DOCUMENT
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
© ISO 2023
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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NATIONAL REGULATIONS.
Website: www.iso.org ISO/DIS 6143:2023(E)
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ii
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PROVIDE SUPPORTING DOCUMENTATION. © ISO 2023

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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
Contents Page
Foreword .iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.3
5 Principle . 4
6 General procedure .6
6.1 Determination of the analysis function . . 6
6.2 Validation of the analysis function . 9
6.2.1 Purpose . 9
6.2.2 Validation of the response model . 9
6.2.3 Examining compliance with uncertainty requirements . 10
6.2.4 Drift control of the measuring system. 10
6.2.5 Validation of applicability to mismatching calibration gases . 11
6.3 Determination of the composition of a calibration gas mixture .12
6.4 Supplementary instructions . 13
6.4.1 Exceptional uncertainties . 13
6.4.2 Correlation between reference gas mixtures . 14
7 Special procedures .14
7.1 Checking of a pre-assigned composition . 14
7.2 Comparison of several calibration gas mixtures . 15
8 Report of results .15
Annex A (normative) Procedures for data evaluation .16
Annex B (informative) Examples .21
Annex C (informative) Computer implementation of recommended methods .29
Annex D (informative) Additional information on data evaluation .31
Bibliography .38
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(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 non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 158, Analysis of Gases.
This third edition cancels and replaces the second edition (ISO 6143:2001), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— update of definitions, in particular those taken from the VIM
— update of the bibliography and the corresponding references in the text
— update of the information in Annex C on the computer programme B_LEAST; information on
alternative software (Annex D)
— amendment of section 6.2 (now 7.2) “Comparison of several calibration gas mixtures” and related
statements in other parts of the Document
— amendment of the recommendations concerning the number of replicate measurements per sample
— revision of the requirements for the report of results (“Test report”)
— new Annex D (informative) “Additional information on data evaluation”, including a comparison
between the regression method used in ISO 6143 and ordinary least-squares regression, providing
information on relevant documents and software, and dealing with the evaluation of replicate
response measurements
— deletion of section A.1 “Uncertainty specifications for reference gas mixtures” that is no longer
required
— additional references to relevant ISO standards (ISO 12963, ISO 14912, ISO 15796)
— correction of the formula for the power function
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
Any feedback or questions on this document should be directed to the user’s national standards body.
A complete listing of these bodies can be found at www.iso.org/members.html.
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
Introduction
In gas analysis, calibration of analytical systems is most often confined to the determination of
a straight line through the origin, or of a straight-line segment, using only the minimum number of
calibration standards (one for a straight line through the origin, two for a line segment). This approach
was also adopted in the first edition (1981) of ISO 6143. However, ISO 6143 is devoted to a very special
task: the derivation of calibration gases from appropriate reference gases. Consequently, the multiplier
effect of errors in calibration gases – an error in a calibration gas may cause errors in thousands of
analytical results – implies high demands on the metrological quality of the analysis of calibration
gases. In the development of the second edition (2001) it was therefore decided to use the best available
measurement strategy and data evaluation method. The main changes in the revision of the (1981)
edition related to calibration as well as to uncertainty evaluation:
— including non-linear response curves and/or functions,
— replacing interpolation by regression,
— taking into account the uncertainty on the calibration standards,
— including validation of calculated response curves and/or functions,
— calculating uncertainties by uncertainty propagation.
After twenty years, the principles and procedures specified in the second edition are still fit for purpose.
The current revision therefore mainly concerns additional supporting information.
As a consequence of adopting non-linear response models, advanced regression techniques (errors in
both variables) and uncertainty propagation, the main calculation procedures can only be performed on
a computer, using a specific program. A dedicated program (B_LEAST) is available and will be provided
without cost (see Annex C). Information on other publicly available software that can be used for at
least the vast majority of the calculations required by ISO 6143 is given in Annex D. As an alternative,
sufficient information is given in the Document to enable the user to develop a program on his own.
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oSIST prEN ISO 6143:2023
DRAFT INTERNATIONAL STANDARD ISO/DIS 6143:2023(E)
Gas analysis — Comparison methods for determining and
checking the composition of calibration gas mixtures
1 Scope
This document provides methods for:
— determining the composition of a calibration gas mixture by comparison with appropriate reference
gas mixtures,
— calculating the uncertainty of the composition of a calibration gas mixture in relation to the known
uncertainty of the composition of the reference gas mixtures with which it was compared,
— checking the composition attributed to a calibration gas mixture by comparison with appropriate
reference gas mixtures,
— consistency testing and outlier search in suites of calibration gas mixtures of closely related
composition.
NOTE In principle, the method described in this document is also applicable to the analysis of (largely)
unknown samples instead of prospective calibration gas mixtures (i.e. gas mixtures which are intended for use
as calibration gas mixtures). Such applications, however, require appropriate care and consideration of additional
uncertainty components, for example concerning the effect of matrix differences between the reference gases
used for calibration and the analysed sample. On the other hand, in many applications one- and two-point
[5]
calibration is preferred over multi-point calibration. ISO 12963 is designed for such applications.
2 Normative references
There are no normative references in this Document.
3 Terms and definitions
For the purposes of this Document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
composition
characteristic of a gas mixture given by the kind and content of each specified mixture component
(analyte) and the composition of the complementary gas (matrix)
Note 1 to entry: In this Document, the analyte content is specified as an amount fraction, exclusively. Amount
fractions have the advantage of being perfectly independent of the pressure and the temperature of the gas
mixture. Therefore their use is recommended. However, for specific measuring systems, other composition
measures (e.g. mass concentrations) may be more appropriate. Their use then requires due care concerning the
dependence on pressure and temperature. Methods for conversion between different quantities of composition
are specified in ISO 14912.
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
3.2
comparison method
method for determining the content of a specified gas mixture component (analyte) by measuring an
instrumental response
Note 1 to entry: Comparison of measuring systems requires calibration, in which the relationship between
response and analyte content is established. This is achieved by measuring the response to known values of
analyte content provided by reference gas mixtures.
3.3
calibration
operation that, under specified conditions, in a first step, establishes a relation between the quantity
values with measurement uncertainties provided by measurement standards and corresponding
indications with associated measurement uncertainties and, in a second step, uses this information to
establish a relation for obtaining a measurement result from an indication
[SOURCE: VIM 3, 2.39]
3.4
response function
functional relationship between instrumental response and analyte content
Note 1 to entry: The response function can be expressed in two different ways as a calibration function or an
analysis function, depending on the choice of the dependent and the independent variable.
Note 2 to entry: The response function is conceptual and cannot be determined exactly. It is determined
approximately through calibration.
3.4.1
calibration function
instrumental response expressed as a function of analyte content
3.4.2
analysis function
analyte content expressed as a function of instrumental response
3.5
measurement uncertainty
uncertainty of measurement
uncertainty
non-negative parameter characterizing the dispersion of the quantity values being attributed to a
measurand, based on the information used
[SOURCE: VIM 3, 2.26]
3.6
metrological traceability
traceability
property of a measurement result whereby the result can be related to a reference through a
documented unbroken chain of calibrations, each contributing to the measurement uncertainty
[SOURCE: VIM 3, 2.41]
3.7
measurement standard
realization of the definition of a given quantity, with stated quantity value and associated measurement
uncertainty, used as a reference
[SOURCE: VIM 3, 5,1]
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
3.8
reference measurement standard
reference standard
measurement standard designated for the calibration of other measurement standards for quantities of
a given kind in a given organization or at a given location
[SOURCE: VIM 3, 5.6]
3.9
working measurement standard
working standard
measurement standard that is used routinely to calibrate or verify measuring instruments or measuring
systems
[SOURCE: VIM 3, 5.7]
3.10
reference material
material, sufficiently homogeneous and stable with reference to specified properties, which has been
established to be fit for its intended use in measurement or in examination of nominal properties
[SOURCE: VIM 3, 5.13]
3.11
calibration gas mixture
gas mixture of known stability and homogeneity whose composition is well established for use in the
calibration or verification of a measuring instrument or for the validation of a measurement
[SOURCE: ISO 7504, 5.1]
3.12
reference gas mixture
calibration gas mixture whose composition is well established and stable to be used as a reference
standard of composition from which other composition data measurements are derived
[SOURCE: ISO 7504, 5.2]
4 Symbols and abbreviated terms
a parameters of the calibration function F ( j = 0, 1, ., N)
j
b parameters of the analysis function G ( j = 0, 1, ., N)
j
D sensitivity matrix
F calibration function, y = F(x), for the specified analyte
G analysis function, x = G(y), for the specified analyte
k coverage factor
L limit of detection
M (sample of) calibration gas mixture
cal
M (sample of) reference gas mixture
ref
Q transform matrix
s standard deviation of a data set (sample standard deviation)
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
S sum of weighted squared deviations
S residual sum of weighted squared deviations
res
t quantile of the t-distribution (ν degrees of freedom, confidence level (1-α))
ν;(1-α)
U(q) expanded uncertainty of an estimated quantity q, U(q) = ku(q)
u(q) uncertainty of an estimated quantity q, expressed as a standard deviation (standard uncer-
tainty)
u(p,q) covariance of two estimated quantities p and q
2
u (q) variance of an estimated quantity q
V variance/covariance matrix
x amount fraction of the specified analyte
(x , y ) calibration points (i = 1, 2, ., n)
i i
adjusted calibration points (i = 1, 2, ., n)
(xyˆˆ )
ii,
y instrumental response of the specified analyte
2 2
χ quantile of the Chi -distribution (ν degrees of freedom, confidence level (1-α))
ν;(1-α)
γ
dilution factor
σ standard deviation of a probability distribution
Γ measure of goodness-of-fit
5 Principle
The composition of a gas mixture is determined by separate determination of the amount fraction
of every specified analyte. Therefore, the procedure for determining the amount fraction of only one
specified analyte is described. Possible interferences of other components on the measurement of the
analyte under consideration should be considered by the user and taken into account. However, this
subject is not addressed in this Document.
This Document is also applicable if other composition quantities than amount fraction are used.
However, it is recommended that the final result be expressed as an amount fraction. Methods for
[6]
conversion between different quantities of composition are specified in ISO 14912 .
The general procedure for determining the amount fraction x of a specified analyte in a sample of a
calibration gas mixture, or in a series of such samples, is performed in a sequence of steps summarized
below.
a) Specify the analytical range of interest, i.e. the range of the amount fractions x to be determined,
and the acceptable uncertainty level (see 6.1, step A).
b) Specify the analytical method and the measuring system to be used (see 6.1, step B).
c) Examine the available information on the relevant response characteristics of the measuring system
(e.g. linearity and sensitivity), paying attention to possible interferences. If necessary, carry out a
performance evaluation to check the suitability of the system. Specify the type of mathematical
function to be considered for description of the response in the specified range (see 6.1, step C).
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
d) Set up a design for the calibration experiment in which the relevant experimental parameters are
specified, such as:
— calibration range (to include the analytical range),
— composition, including uncertainty, of the reference gas mixtures for calibration,
— parameters of the analytical method,
— conditions of measurement, if relevant,
— number and sequence of calibration measurements (see 6.1, steps D, E, F).
e) Perform the calibration experiment, i.e. measure the response, y, for samples of the chosen reference
gas mixtures, and estimate the uncertainty u(y) of these response values (see 6.1, step G).
f) Calculate the analysis function, x = G(y), from the calibration data, using regression analysis
(see 6.1, step H).
g) Examine whether the calculated analysis function is consistent with the calibration data within the
relevant uncertainties. If the result is acceptable, proceed to h). If not, revise the calibration design
(see 6.2.2).
h) Determine the uncertainty level of the prospective results based on the analysis function for the
relevant ranges of responses and analyte contents. If the result is acceptable, proceed to i). If not,
revise the calibration design (see 6.2.3).
i) Prior to analysing a prospective calibration gas sample, test for instrument drift to ensure that the
analysis function is still valid for the specified analytical task (see 6.2.4). If the result is acceptable,
proceed to j). If not, recalibrate the measuring system.
If the prospective calibration gas contains other components than the reference gas mixtures
used for calibration, validate the applicability of the analysis function using at least one additional
reference gas mixture of appropriate composition (see 6.2.5).
NOTE It is not necessary to test for drift in conjunction with every analysis of a calibration gas sample.
The frequency should be based on experience concerning the stability of the measuring system.
Similarly, the composition of additional reference gas mixtures used for validation should be based on
experience concerning the cross-sensitivities of the measuring system.
j) Determine the composition of the prospective calibration gas as follows:
— measure the response y,
— determine the uncertainty u(y) of the response y,
— calculate the amount fraction x = G(y) using the analysis function determined in f),
— calculate the uncertainty u(x) of the amount fraction x by propagation of uncertainty on the
measured response and on the parameters of the analysis function (see 6.3).
k) State the result of the entire analysis (see clause 8).
In addition to determining the composition of a (prospective) calibration gas mixture, the general
procedure may be used to check a pre-established composition. To this end, the mixture under
consideration is analysed using the procedure outlined above, and the composition obtained is
compared with the pre-established composition. Clause 7 specifies a procedure where, for each analyte
concerned, the difference between the content obtained by the confirmation analysis and the pre-
established content is examined against the uncertainty on this difference for significant departure
from zero.
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oSIST prEN ISO 6143:2023
ISO/DIS 6143:2023(E)
The general procedure may also be used for consistency testing and outlier search in suites of
calibration gas mixtures of closely related composition. Clause 7 specifies a procedure where entire
suites of calibration gases are measured in a calibration experiment, using an analyser with linear
response. For each analyte concerned the calibration data are examined for compatibility with a
straight-line response curve. A positive test result provides confirmation that the assigned contents
and their uncertainties are mutually consistent. Restriction to subsets provides a tool for outlier search
in cases of a negative test result.
6 General procedure
6.1 Determination of the analysis function
For a specified analyte and a specified measuring system, including relevant operating conditions, the
calibration function, y = F(x), is a mathematical function approximately expressing measured responses
y , y , ., y in relation to known analyte contents x , x , ., x of appropriate reference gas mixtures.
1 2 n 1 2 n
Inversely, the analysis function, x = G(y), approximately expresses known analyte contents x , x , .,
1 2
x in relation to corresponding measured responses y , y , ., y . The analysis function is required for
n 1 2 n
calculating unknown analyte contents x of calibration gas mixtures from measured responses y.
The analysis function can be determined either directly, or indirectly by determination of the
calibration function and subsequent inversion. It is recommended to make a direct determination of the
analysis function. Therefore, only this procedure is specified in the body of this Document. In particular
applications, however, indirect determination using the calibration function may be preferable. For
such applications, a brief description of this
...