SIST EN ISO 19396-1:2020
(Main)Paints and varnishes - Determination of pH value - Part 1: pH electrodes with glass membrane (ISO 19396-1:2017)
Paints and varnishes - Determination of pH value - Part 1: pH electrodes with glass membrane (ISO 19396-1:2017)
ISO 19396-1:2017 specifies a method for laboratory measurement of the pH value of polymer dispersions and coating materials using pH electrodes with a glass membrane.
Beschichtungsstoffe - Bestimmung des pH-Wertes - Teil 1: pH-Elektroden mit Glasmembran (ISO 19396-1:2017)
Dieses Dokument legt ein Verfahren zum Messen des pH Wertes von Polymerdispersionen und Beschichtungsstoffen mit pH Elektroden mit Glasmembran im Labor fest. ISO 19396 2 legt ein Verfahren zum Messen des pH Wertes mit pH Elektroden mit ISFET-Technologie (Ionensensitiver Feldeffekt-Transistor) fest.
Peintures et vernis - Détermination de la valeur pH - Partie 1: Électrodes pH avec membrane de verre (ISO 19396-1:2017)
Le présent document spécifie une méthode de mesure en laboratoire de la valeur de pH des dispersions de polymères et des produits de peinture à l'aide d'électrodes de pH pourvues d'une membrane en verre. L'ISO 19396-2 spécifie une méthode de mesure de la valeur de pH à l'aide d'électrodes de pH dotées de la technologie de transistor à effet de champ sensible aux ions (ISFET).
Barve in laki - Določevanje pH-vrednosti - 1. del: pH-elektrode s stekleno membrano (ISO 19396-1:2017)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 19396-1:2020
01-april-2020
Barve in laki - Določevanje pH-vrednosti - 1. del: pH-elektrode s stekleno
membrano (ISO 19396-1:2017)
Paints and varnishes - Determination of pH value - Part 1: pH electrodes with glass
membrane (ISO 19396-1:2017)
Beschichtungsstoffe - Bestimmung des pH-Wertes - Teil 1: pH-Elektroden mit
Glasmembran (ISO 19396-1:2017)
Peintures et vernis - Détermination de la valeur pH - Partie 1: Électrodes pH avec
membrane de verre (ISO 19396-1:2017)
Ta slovenski standard je istoveten z: EN ISO 19396-1:2020
ICS:
87.040 Barve in laki Paints and varnishes
SIST EN ISO 19396-1:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST EN ISO 19396-1:2020
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SIST EN ISO 19396-1:2020
EN ISO 19396-1
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2020
EUROPÄISCHE NORM
ICS 87.040
English Version
Paints and varnishes - Determination of pH value - Part 1:
pH electrodes with glass membrane (ISO 19396-1:2017)
Peintures et vernis - Détermination de la valeur pH - Beschichtungsstoffe - Bestimmung des pH-Wertes -
Partie 1: Électrodes pH avec membrane de verre (ISO Teil 1: pH-Elektroden mit Glasmembran (ISO 19396-
19396-1:2017) 1:2017)
This European Standard was approved by CEN on 4 November 2019.
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, Turkey 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
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19396-1:2020 E
worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 19396-1:2020
EN ISO 19396-1:2020 (E)
Contents Page
European foreword . 3
2
---------------------- Page: 4 ----------------------
SIST EN ISO 19396-1:2020
EN ISO 19396-1:2020 (E)
European foreword
The text of ISO 19396-1:2017 has been prepared by Technical Committee ISO/TC 35 "Paints and
varnishes” of the International Organization for Standardization (ISO) and has been taken over as
EN ISO 19396-1:2020 by Technical Committee CEN/TC 139 “Paints and varnishes” 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 August 2020, and conflicting national standards shall
be withdrawn at the latest by August 2020.
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.
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, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 19396-1:2017 has been approved by CEN as EN ISO 19396-1:2020 without any
modification.
3
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SIST EN ISO 19396-1:2020
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SIST EN ISO 19396-1:2020
INTERNATIONAL ISO
STANDARD 19396-1
First edition
2017-08
Paints and varnishes — Determination
of pH value —
Part 1:
pH electrodes with glass membrane
Peintures et vernis — Détermination de la valeur pH —
Partie 1: Électrodes pH avec membrane de verre
Reference number
ISO 19396-1:2017(E)
©
ISO 2017
---------------------- Page: 7 ----------------------
SIST EN ISO 19396-1:2020
ISO 19396-1:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 19396-1:2020
ISO 19396-1:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 5
5 Apparatus and materials. 5
6 Sampling . 8
7 Procedure. 8
7.1 Test conditions . 8
7.2 Calibration . 8
7.3 Number of determinations . 9
7.4 Measuring the pH value . 9
8 Evaluation . 9
9 Precision . 9
9.1 General . 9
9.2 Repeatability limit, r . 9
9.3 Reproducibility limit, R .10
10 Test report .10
Annex A (informative) Recommended pH electrodes for different groups of coating
materials, based on the results of interlaboratory tests .11
Annex B (informative) Determination of precision .13
Bibliography .15
© ISO 2017 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 19396-1:2020
ISO 19396-1:2017(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 on 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 the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee
SC 9, General test methods for paints and varnishes.
A list of all parts in the ISO 19396 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 19396-1:2020
ISO 19396-1:2017(E)
Introduction
The pH value of aqueous products is of decisive importance for the product properties and durability.
© ISO 2017 – All rights reserved v
---------------------- Page: 11 ----------------------
SIST EN ISO 19396-1:2020
---------------------- Page: 12 ----------------------
SIST EN ISO 19396-1:2020
INTERNATIONAL STANDARD ISO 19396-1:2017(E)
Paints and varnishes — Determination of pH value —
Part 1:
pH electrodes with glass membrane
1 Scope
This document specifies a method for laboratory measurement of the pH value of polymer dispersions
and coating materials using pH electrodes with a glass membrane. ISO 19396-2 specifies a method
for measuring the pH value using pH electrodes with ion-sensitive field-effect transistor (ISFET)
technology.
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 1513, Paints and varnishes — Examination and preparation of test samples
ISO 4618, Paints and varnishes — Terms and definitions
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
ISO 80000-9:2009, Quantities and units — Part 9: Physical chemistry and molecular physics
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 4618 and ISO 80000-9 and the
following 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
pH
measure for the acidic or basic reaction of an aqueous solution or polymer dispersion
Note 1 to entry: Notation of pH: the p and the H are vertically on one line. The same is valid for pOH.
Note 2 to entry: The acidic reaction is determined by the activity of the existing “hydrogen ions”. The basic
reaction is determined by the activity of the existing hydroxide ions. The direct relationship between the
activities of the “hydrogen ions” and the hydroxide ions is described by the ionic product of the water.
3.2
pH value
decadal logarithm of the hydrogen ion activity multiplied with (−1)
m ⋅γ
a ++
+
HHm,
H
pH==p a −lg =−lg
+
H 00
m m
© ISO 2017 – All rights reserved 1
---------------------- Page: 13 ----------------------
SIST EN ISO 19396-1:2020
ISO 19396-1:2017(E)
with am=⋅γ
++ +
HH m,H
where
is the activity of the hydrogen ion, in mol/kg;
a
+
H
0 is the standard molality (1 mol/kg);
m
is the activity coefficient of the hydrogen ion;
γ
+
m,H
is the molality of the hydrogen ion, in mol/kg.
m
+
H
Note 1 to entry: The pH value is not measurable as a measure of a single ion activity. Therefore, pH (PS) values of
solutions of primary reference material (PS, en: Primary Standard) are determined, which are approximate to it
and can be attributed to it. This is based on a worldwide agreement; see ISO 80000-9:2009, Annex C.
3.3
potentiometric measuring chain
combination of electrochemical half cells
3.4
pH (combination) electrode
pH (single-rod) measuring chain
potentiometric measuring chain (3.3) providing a voltage which depends on the pH value (3.2) of the
measuring solution
Note 1 to entry: One of the two electrochemical half cells is the pH measuring electrode, the second is a reference
electrode (3.5) (see Figure 1). Both electrodes can be combined as a single-rod measuring chain in one unit.
Note 2 to entry: An integrated temperature sensor is recommended (see Figure 1).
2 © ISO 2017 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 19396-1:2020
ISO 19396-1:2017(E)
Key
1 reference electrode, consisting of 2, 3 and 4 6 reference element
2 reference element 7 glass membrane
3 reference electrolyte 8 internal buffer
4 diaphragm 9 temperature sensor
5 pH measuring electrode, consisting of 6, 7 and 8 U pH proportional voltage
Figure 1 — Design of a pH electrode with glass membrane and temperature sensor
(schematic illustration)
Note 3 to entry: This document refers to pH electrodes with glass membrane. The electrode shaft should be made
of material resistant to chemicals and solvents.
3.5
reference electrode
electrode providing a constant potential which is independent from the pH value (3.2) of the
measuring medium
Note 1 to entry: At present, the most commonly used type is the silver/silver chloride reference electrode, whose
potential is stabilized by a constant concentration of potassium chloride (KCl) in the reference electrolyte (3.7).
3.6
reference element
galvanic cell which dips into the reference electrolyte (3.7) and transmits the reference potential to the
pH meter
Note 1 to entry: The reference elements of the pH measuring electrode and of the reference electrode should be
aligned so that identical temperature characteristics are given.
© ISO 2017 – All rights reserved 3
---------------------- Page: 15 ----------------------
SIST EN ISO 19396-1:2020
ISO 19396-1:2017(E)
3.7
reference electrolyte
aque
...
SLOVENSKI STANDARD
oSIST prEN ISO 19396-1:2019
01-julij-2019
Barve in laki - Določevanje pH-vrednosti - 1. del: pH-elektrode s stekleno
membrano (ISO 19396-1:2017)
Paints and varnishes - Determination of pH value - Part 1: pH electrodes with glass
membrane (ISO 19396-1:2017)
Beschichtungsstoffe - Bestimmung des pH-Wertes - Teil 1: pH-Elektroden mit
Glasmembran (ISO 19396-1:2017)
Peintures et vernis - Détermination de la valeur pH - Partie 1: Électrodes pH avec
membrane de verre (ISO 19396-1:2017)
Ta slovenski standard je istoveten z: prEN ISO 19396-1
ICS:
87.040 Barve in laki Paints and varnishes
oSIST prEN ISO 19396-1:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST prEN ISO 19396-1:2019
---------------------- Page: 2 ----------------------
oSIST prEN ISO 19396-1:2019
INTERNATIONAL ISO
STANDARD 19396-1
First edition
2017-08
Paints and varnishes — Determination
of pH value —
Part 1:
pH electrodes with glass membrane
Peintures et vernis — Détermination de la valeur pH —
Partie 1: Électrodes pH avec membrane de verre
Reference number
ISO 19396-1:2017(E)
©
ISO 2017
---------------------- Page: 3 ----------------------
oSIST prEN ISO 19396-1:2019
ISO 19396-1:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST prEN ISO 19396-1:2019
ISO 19396-1:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 5
5 Apparatus and materials. 5
6 Sampling . 8
7 Procedure. 8
7.1 Test conditions . 8
7.2 Calibration . 8
7.3 Number of determinations . 9
7.4 Measuring the pH value . 9
8 Evaluation . 9
9 Precision . 9
9.1 General . 9
9.2 Repeatability limit, r . 9
9.3 Reproducibility limit, R .10
10 Test report .10
Annex A (informative) Recommended pH electrodes for different groups of coating
materials, based on the results of interlaboratory tests .11
Annex B (informative) Determination of precision .13
Bibliography .15
© ISO 2017 – All rights reserved iii
---------------------- Page: 5 ----------------------
oSIST prEN ISO 19396-1:2019
ISO 19396-1:2017(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 on 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 the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee
SC 9, General test methods for paints and varnishes.
A list of all parts in the ISO 19396 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST prEN ISO 19396-1:2019
ISO 19396-1:2017(E)
Introduction
The pH value of aqueous products is of decisive importance for the product properties and durability.
© ISO 2017 – All rights reserved v
---------------------- Page: 7 ----------------------
oSIST prEN ISO 19396-1:2019
---------------------- Page: 8 ----------------------
oSIST prEN ISO 19396-1:2019
INTERNATIONAL STANDARD ISO 19396-1:2017(E)
Paints and varnishes — Determination of pH value —
Part 1:
pH electrodes with glass membrane
1 Scope
This document specifies a method for laboratory measurement of the pH value of polymer dispersions
and coating materials using pH electrodes with a glass membrane. ISO 19396-2 specifies a method
for measuring the pH value using pH electrodes with ion-sensitive field-effect transistor (ISFET)
technology.
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 1513, Paints and varnishes — Examination and preparation of test samples
ISO 4618, Paints and varnishes — Terms and definitions
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
ISO 80000-9:2009, Quantities and units — Part 9: Physical chemistry and molecular physics
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 4618 and ISO 80000-9 and the
following 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
pH
measure for the acidic or basic reaction of an aqueous solution or polymer dispersion
Note 1 to entry: Notation of pH: the p and the H are vertically on one line. The same is valid for pOH.
Note 2 to entry: The acidic reaction is determined by the activity of the existing “hydrogen ions”. The basic
reaction is determined by the activity of the existing hydroxide ions. The direct relationship between the
activities of the “hydrogen ions” and the hydroxide ions is described by the ionic product of the water.
3.2
pH value
decadal logarithm of the hydrogen ion activity multiplied with (−1)
m ⋅γ
a ++
+
HHm,
H
pH==p a −lg =−lg
+
H 00
m m
© ISO 2017 – All rights reserved 1
---------------------- Page: 9 ----------------------
oSIST prEN ISO 19396-1:2019
ISO 19396-1:2017(E)
with am=⋅γ
++ +
HH m,H
where
is the activity of the hydrogen ion, in mol/kg;
a
+
H
0 is the standard molality (1 mol/kg);
m
is the activity coefficient of the hydrogen ion;
γ
+
m,H
is the molality of the hydrogen ion, in mol/kg.
m
+
H
Note 1 to entry: The pH value is not measurable as a measure of a single ion activity. Therefore, pH (PS) values of
solutions of primary reference material (PS, en: Primary Standard) are determined, which are approximate to it
and can be attributed to it. This is based on a worldwide agreement; see ISO 80000-9:2009, Annex C.
3.3
potentiometric measuring chain
combination of electrochemical half cells
3.4
pH (combination) electrode
pH (single-rod) measuring chain
potentiometric measuring chain (3.3) providing a voltage which depends on the pH value (3.2) of the
measuring solution
Note 1 to entry: One of the two electrochemical half cells is the pH measuring electrode, the second is a reference
electrode (3.5) (see Figure 1). Both electrodes can be combined as a single-rod measuring chain in one unit.
Note 2 to entry: An integrated temperature sensor is recommended (see Figure 1).
2 © ISO 2017 – All rights reserved
---------------------- Page: 10 ----------------------
oSIST prEN ISO 19396-1:2019
ISO 19396-1:2017(E)
Key
1 reference electrode, consisting of 2, 3 and 4 6 reference element
2 reference element 7 glass membrane
3 reference electrolyte 8 internal buffer
4 diaphragm 9 temperature sensor
5 pH measuring electrode, consisting of 6, 7 and 8 U pH proportional voltage
Figure 1 — Design of a pH electrode with glass membrane and temperature sensor
(schematic illustration)
Note 3 to entry: This document refers to pH electrodes with glass membrane. The electrode shaft should be made
of material resistant to chemicals and solvents.
3.5
reference electrode
electrode providing a constant potential which is independent from the pH value (3.2) of the
measuring medium
Note 1 to entry: At present, the most commonly used type is the silver/silver chloride reference electrode, whose
potential is stabilized by a constant concentration of potassium chloride (KCl) in the reference electrolyte (3.7).
3.6
reference element
galvanic cell which dips into the reference electrolyte (3.7) and transmits the reference potential to the
pH meter
Note 1 to entry: The reference elements of the pH measuring electrode and of the reference electrode should be
aligned so that identical temperature characteristics are given.
© ISO 2017 – All rights reserved 3
---------------------- Page: 11 ----------------------
oSIST prEN ISO 19396-1:2019
ISO 19396-1:2017(E)
3.7
reference electrolyte
aqueous salt solution (generally potassium chloride solution), whose chloride ion activity determines
the potential of the reference electrode (3.5)
Note 1 to entry: At the diaphragm (3.8), the reference electrolyte has contact with the measuring solution.
+ −
Potassium chloride solution is used as reference electrolyte, because K ions and Cl ions have almost the same
ion mobility and, therefore, only slight diffusion potentials result.
Note 2 to entry: The reference electrolyte should flow out of the diaphragm in order to ensure a constant
reference potential. Therefore, it shall be refilled occasionally. For reference electrodes (3.5) or pH electrodes (3.4)
with thickened/gel or solidified electrolyte, refilling of the electrolyte can be omitted. Such reference electrodes
or pH electrodes are called low-maintenance.
3.8
diaphragm
permeable material in the sides of the casing of reference electrodes (3.5), which enables the electrolytic
contact between reference electrolytes (3.7) and measuring solution and simultaneously impedes the
exchange of electrolyte
Note 1 to entry: For types of diaphragms, see 5.3.
3.9
measuring electrode with glass membrane
electrode providing a potential which is a function of the pH value (3.2)
3.10
pH glass membrane
membrane made of special glass, on whose interface to the solution an electrical potential (electrode
function) results, which is proportional to the pH (3.1) of the solution
3.11
temperature compensation
compensation of the temperature-dependent measuring signal only of the buffer solutions (3.15) with
known temperature dependency
Note 1 to entry: By this, the temperature dependency of the pH value (3.2) of the measuring medium cannot be
compensated. Therefore, the temperature is always recorded together with the pH value.
3.12
theoretical slope
k
change of the voltage of the pH electrode (3.4) with temperature
R⋅TTR⋅
k =− ⋅=ln10 −⋅2,303
F F
where
T is the thermodynamic temperature, in Kelvin
...
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