prEN 17721

Plant biostimulants - Determination of the pH for liquid microbial plant biostimulants/pH in microbial products - Determination of pH

This document specifies a method for laboratory measurement of the pH value in liquid microbial plant biostimulants, using pH electrodes with a glass membrane.
Plant biostimulants other than microbial plant biostimulants are excluded from the scope of this document because there is no essential requirement in the Regulation [1] for measuring the pH of non-microbial plant biostimulants.

Pflanzen-Biostimulanzien - Bestimmung des pH‑Wertes für flüssige mikrobielle Pflanzen-Biostimulanzien/pH‑Wert in mikrobiellen Produkten - Bestimmung des pH‑Wertes

Dieses Dokument legt ein Verfahren zur Messung des pH Wertes in flüssigen mikrobiellen Pflanzen-Biostimulanzien im Labor unter Verwendung von pH Elektroden mit einer Glasmembran fest.
Andere Pflanzen-Biostimulanzien als mikrobielle Pflanzen-Biostimulanzien gehören nicht zum Anwendungsbereich dieses Dokuments, da die Verordnung [1] keine grundlegenden Anforderungen hinsichtlich der Messung des pH Wertes von nicht-mikrobiellen Pflanzen-Biostimulanzien enthält.

Biostimulants des végétaux - Détermination du pH des biostimulants microbiens liquides des végétaux/pH dans les produits microbiens - Détermination du pH

Le présent document spécifie une méthode de mesure en laboratoire de la valeur du pH dans les biostimulants microbiens des végétaux sous forme liquide, à l’aide d’électrodes de pH avec une membrane en verre.
Les biostimulants des végétaux autres que les biostimulants microbiens des végétaux sont exclus du domaine d’application du présent document, car il n’existe pas d’exigence essentielle dans le Règlement [1] de mesure du pH des biostimulants des végétaux non microbiens.

Rastlinski biostimulanti - Določanje pH-vrednosti za tekoče mikrobne biostimulante/mikrobne proizvode - Določanje pH-vrednosti

General Information

• Status: Not Published
• Publication Date: 08-Jul-2024
• ICS: 65.080 - Fertilizers
• Technical Committee: CEN/TC 455 - Plant Biostimulants and Agricultural Micro-Organisms
• Drafting Committee: CEN/TC 455/WG 3 - Pathogenic and non-pathogenic microorganisms
• Current Stage: 4060 - Closure of enquiry - Enquiry
• Start Date: 06-Jul-2023
• Due Date: 14-Feb-2023
• Completion Date: 06-Jul-2023
• Directive: 2019/1009 - Regulation (EU) 2019/1009 of the European Parliament and of the Council of 5 June 2019 laying down rules on the making available on the market of EU fertilising products and amending Regulations (EC) No 1069/2009 and (EC) No 1107/2009 and repealing Regulation (EC) No 2003/2003
• Mandate: M/564 - Fertilising products in support of Regulation (EU) 2019/1009
• Mandate: M/564 AMD 1 - amending Implementing Decision C(2020) 612 as regards certain harmonised standards and standardisation deliverables, deadlines for their adoption and the duration of the validity of the standardisation request
• Mandate: M/XXX - Ambient Air Sensor systems and data quality objectives
• Ref Project: oSIST prEN 17721:2023 - Plant biostimulants - Determination of the pH for liquid microbial plant biostimulants/pH in microbial products - Determination of pH

Relations

• Revises: CEN/TS 17721:2022 - Plant biostimulants - Determination of the pH for liquid microbial plant biostimulants/pH in microbial products - Determination of pH
• Effective Date: 15-Feb-2023

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN 17721:2023
01-maj-2023
Rastlinski biostimulanti - Določanje pH-vrednosti za tekoče mikrobne
biostimulante/mikrobne proizvode - Določanje pH-vrednosti
Plant biostimulants - Determination of the pH for liquid microbial plant biostimulants/pH in
microbial products - Determination of pH
Pflanzen-Biostimulanzien - Bestimmung des pH Wertes für flüssige mikrobielle Pflanzen-
Biostimulanzien/pH Wert in mikrobiellen Produkten - Bestimmung des pH Wertes
Biostimulants des végétaux - Détermination du pH des biostimulants microbiens liquides
des végétaux/pH dans les produits microbiens - Détermination du pH
Ta slovenski standard je istoveten z: prEN 17721
ICS:
65.080 Gnojila Fertilizers
oSIST prEN 17721:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 17721:2023

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oSIST prEN 17721:2023


DRAFT
EUROPEAN STANDARD
prEN 17721
NORME EUROPÉENNE

EUROPÄISCHE NORM

April 2023
ICS 65.080 Will supersede CEN/TS 17721:2022
English Version

Plant biostimulants - Determination of the pH for liquid
microbial plant biostimulants/pH in microbial products -
Determination of pH
Biostimulants des végétaux - Détermination du pH des Pflanzen-Biostimulanzien - Bestimmung des pH Wertes
biostimulants microbiens liquides des végétaux/pH für flüssige mikrobielle Pflanzen-Biostimulanzien/pH
dans les produits microbiens - Détermination du pH Wert in mikrobiellen Produkten - Bestimmung des pH
Wertes
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 455.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17721:2023 E
worldwide for CEN national Members.

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prEN 17721:2023 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 9
5 Apparatus and materials . 9
5.1 General . 9
5.2 pH measuring apparatus . 9
5.3 Water . 10
5.4 pH meter . 10
5.5 pH electrode . 11
5.6 Standard buffer solutions . 11
5.7 Storage solution for the pH electrodes . 11
6 Sampling . 11
7 Procedure. 12
7.1 General . 12
7.2 Test conditions . 12
7.3 Calibration . 12
7.4 Number of determinations . 12
7.5 Measuring the pH value . 12
8 Evaluation . 13
9 Precision . 13
10 Test report . 13
Annex A (informative) Repeatability and Reproducibility data . 14
A.1 Materials used in the interlaboratory study . 14
A.2 Samples . 14
A.3 Procedure. 14
A.4 Replicate determination . 14
A.5 Results . 14
Annex ZA (informative) Relationship of this European Standard and the essential
requirements of Regulation (EU) 2019/1009 making available on the market of EU
fertilising products aimed to be covered. 17
Bibliography . 18
2

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prEN 17721:2023 (E)
European foreword
This document (prEN 17721:2023) has been prepared by Technical Committee CEN/TC 455 “Plant
Biostimulants”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN enquiry.
This document will supersede CEN/TS 17721:2022.
This document has been prepared under a Standardization Request given to CEN by the European
Commission and the European Free Trade Association, and supports essential requirements of EU
Directive(s) / Regulation(s).
For relationship with EU Directive(s) / Regulation(s), see informative Annex ZA, which is an integral part
of this document.
3

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oSIST prEN 17721:2023
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Introduction
The new Fertilising Products Regulation (Reg. (EU) 2019/1009) introduces new requirements related to
quality, safety, and labelling of fertilizing products and extends the scope to organic fertilizers, organo-
mineral fertilizers, growing media, biostimulants and others. The Regulation harmonizes EU rules for
products derived from waste organic materials and by products, and provides rules to recover nutrients
into secondary raw materials – largely boosting the EU Circular Economy.
CEN/TC 455 “Plant Biostimulants” is one of the three Technical Committees in charge of developing
deliverables to ensure full harmonization of fertilizing products on the European Single Market under the
Fertilizing Products Regulation, standardizing terminology, specifications, testing methods for safety and
environmental criteria of the fertilizing products.
This document was prepared by the experts of CEN/TC 455 “Plant Biostimulants”. The European
Committee for Standardization (CEN) was requested by the European Commission (EC) to draft
European standards or European standardization deliverables to support the implementation of
Regulation (EU) 2019/1009 of 5 June 2019 laying down rules on the making available on the market of
EU fertilising products (“FPR” or “Fertilising Products Regulation”). This standardization request,
presented as SR M/564, also contributes to the Communication on “Innovating for Sustainable Growth:
A Bio economy for Europe”. Working Group 5 “Labelling and denominations”, was created to develop a
work program as part of this standardization request.
Technical committee CEN/TC 455 “Plant Biostimulants” was established to carry out the work program
that will prepare a series of standards. The interest in biostimulants has increased significantly in Europe
as a valuable tool to use in agriculture. Standardization was identified as having an important role in
order to promote the use of biostimulants. The work of CEN/TC 455 seeks to improve the reliability of
the supply chain, thereby improving the confidence of farmers, industry, and consumers in biostimulants,
and will promote and support commercialisation of the European biostimulant industry.
Liquid microbial plant biostimulants have a pH optimal for contained microorganisms and for plants [1].
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices and to ensure compliance
with any national regulatory conditions.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document be
carried out by suitably trained staff.
4

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1 Scope
This document specifies a method for laboratory measurement of the pH value in liquid microbial plant
biostimulants, using pH electrodes with a glass membrane.
Plant biostimulants other than microbial plant biostimulants are excluded from the scope of this
document because there is no essential requirement in the Regulation [1] for measuring the pH of non-
microbial plant biostimulants.
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.
1
EN 17702-1:— , Plant biostimulants — Sampling and sample preparation — Part 1: Sampling
2
EN 17702-2:— , Plant biostimulants — Sampling and sample preparation — Part 2: Sample preparation
3
EN 17724:— , Plant biostimulants — Terminology
EN ISO 3696:1995, Water for analytical laboratory use — Specification and test methods (ISO 3696:1987)
3 Terms and definitions
3
For the purposes of this document, the terms and definitions given in EN 17724:— 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
pH
measure for the acidic or basic reaction of an aqueous solution or dispersion
Note 1 to entry: Notation of pH: the p and the H are vertically on one line.
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.

1
Under preparation
2
Under preparation
3
Under preparation
5

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3.2
pH value
decadal logarithm of the hydrogen ion activity multiplied with (−1)

 m ⋅ γ
a
H++mH,
H+

pH= pa =−lg= −lg
H+


m m
00


with
am= ⋅γ
H++H mH, +

where
+
a is the activity of the hydrogen ion, expressed in mole per kilogram (mol/kg);
H
m is the standard molality expressed in mole per kilogram (mol/kg);
0
γ is the activity coefficient of the hydrogen ion;
m,H+
+
m is the molality of the hydrogen ion, expressed in mole per kilogram (mol/kg).
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 approximated to it
and can be attributed to it. This is based on a worldwide agreement; see EN ISO 80000-9:2019, Annex C [3].
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).
Note 2 to entry: An integrated temperature sensor is recommended (see Figure 1).
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Key
1 reference electrode, consisting in 2, 3 and 4
2 reference element
3 reference electrolyte
4 diaphragm
5 pH measuring electrode, consisting of 6, 7 and 8
6 reference element
7 glass membrane
8 internal buffer
9 temperature sensor
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 membranes. 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.
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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.
+ −
ions and Cl ions have almost the same ion
Potassium chloride solution is used as reference electrolyte, because K
mobility and, therefore, only slight diffusion potential 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 electr
...