FprEN 18252

SLOVENSKI STANDARD
01-december-2025
Izboljševalci tal in rastni substrati - Določanje klorida
Soil improvers and growing media - Determination of the chloride content
Bodenverbesserungsmittel und Kultursubstrate - Bestimmung des Chloridgehaltes
Amendements du sol et supports de culture - Détermination de la teneur en chlorures
Ta slovenski standard je istoveten z: prEN 18252
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 18252
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2025
ICS 65.080
English Version
Soil improvers and growing media - Determination of the
chloride content
Amendements du sol et supports de culture - Bodenverbesserungsmittel und Kultursubstrate -
Détermination de la teneur en chlorures Bestimmung des Chloridgehaltes
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 223.
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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18252:2025 E
worldwide for CEN national Members.

prEN 18252:2025 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
4.1 General. 4
4.2 Interferences . 4
5 Reagents . 4
6 Apparatus and equipment . 5
7 Sampling . 6
8 Procedure . 6
8.1 General. 6
8.2 Temperature for measurements . 6
8.3 Extraction of materials . 6
8.3.1 General. 6
8.3.2 Extraction of materials in solid form . 6
8.3.3 Extraction of materials in pre-shaped form . 7
8.3.4 Filtration . 7
8.3.5 Liquid materials . 7
8.4 Determination by potentiometric titration . 7
8.4.1 Preparation of test portion (sample) . 7
8.4.2 Blank test . 7
8.4.3 Recovery test (mandatory) . 8
9 Calculation and expression of the results . 8
10 Test report . 9
11 Validation of the method . 10
11.1 Validation in accordance with ISO 5725-2. 10
11.2 Performance characteristics. 10
Annex A (normative) Preparation and standardization of 0,1 mol/l silver nitrate solution . 11
Annex B (informative) Performance characteristics of the method . 12
Bibliography . 14

prEN 18252:2025 (E)
European foreword
This document (prEN 18252:2025) has been prepared by Technical Committee CEN/TC 223 “Soil
improvers and growing media”, the secretariat of which is held by NEN. This document was prepared in
collaboration with CEN/TC 260 “Fertilizers and liming materials”.
This document is currently submitted to the CEN Enquiry.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
prEN 18252:2025 (E)
1 Scope
-
This document specifies a method for the determination of the chloride (Cl ) content by potentiometric
titration. This method is applicable to growing media and soil improvers.
NOTE It is possible to use other analytical techniques (e.g. ion chromatography, discrete analyser, continuous
flow analyser); in this case a validation is carried out by the laboratory for the procedure and data generated.
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.
CEN/TS 17732:2022, Soil improvers and growing media - Terminology
EN 12579:2024, Soil improvers and growing media - Sampling
prEN 13040-1:2025, Soil improvers and growing media — Sample preparation — Part 1: Sample
preparation for chemical and physical tests, determination of dry matter content, moisture content and
laboratory bulk density
3 Terms and definitions
For the purposes of this document, the following terms and definitions given in CEN/TS 17732:2022 and
the following apply.
3.1
chloride content
mass fraction of chlorides, expressed in g/kg of dry matter, determined in accordance with the procedure
described in this document
4 Principle
4.1 General
Soluble chlorides are extracted from the sample with water containing nitric acid. The chloride content
of the solution is titrated with silver nitrate standard solution. The end point is determined
potentiometrically by using either a silver ion selective electrode plus a reference electrode or a
combined electrode.
4.2 Interferences
-
Maintaining the sample at a lower pH can avoid the silver ion from interacting with OH to precipitate as
silver oxide (Ag O), it minimizes the interference of other anions with AgCl formation, and it improves
the binding between the titrant and the analyte.
5 Reagents
Only reagents of recognized analytical grade shall be used.
5.1 Water, with a specific conductivity not higher than 0,2 mS/m at 25 °C, free from the elements shall
be used.
5.2 Nitric acid concentrated, 70 % w/v, p.a.
prEN 18252:2025 (E)
5.3 Nitric acid solution
It shall dilute 1:1 concentrated nitric acid (5.2) in water (5.1).
5.4 Silver nitrate standard solution, c = 0,1 mol/l solution.
The silver nitrate solution of 0,1 mol/l in water (5.1) shall be prepared. Many silver nitrate solutions
ready-to-use are commercially available with the certified concentration.
If an in-house solution is prepared, it shall be standardized following the instructions in Annex A.
5.5 Polyvinyl alcohol (PVA) solution, acidified with nitric acid.
It is recommended to use an acidified protector colloid medium for the potentiometric titration.
2 g of polyvinyl alcohol (PVA) shall be mixed with 400 ml of hot water (approximately 90 °C) in a 1 000 ml
one-mark volumetric glass flask (6.3) and let it cool to room temperature. Nitric acid (5.3) shall be added
for an amount of 10ml, then filled up with water to 1 000 ml.
5.6 Sodium chloride, p.a., for the standardization of silver nitrate solution (5.4)
For the preparation of sodium chloride solution, the instructions in Annex A shall be followed.
Many solutions ready-to-use are commercially available with concentration c = 0,01 mol/l.
6 Apparatus and equipment
This method describes manual titrations. Automatic titrators may be used. Ordinary laboratory
equipment and the following shall be used.
6.1 Electromagnetic stirrer and polytetrafluoroethylene (PTFE) coated magnetic bars.
6.2 Glass burettes, class A or AS [4], with a reading accuracy of 0,02 ml, or automatic pipettes with a
reading accuracy of 0,002 ml.
6.3 One-mark volumetric glass flasks, Class A [5], capacity 150 ml, 500 ml and 1 000 ml.
6.4 Glass beaker [6], capacity 300 ml.
6.5 Glass conical (Erlenmeyer) flask, capacity 250 ml.
6.6 Potentiometer, with a reading accuracy of 0,1 mV, equipped with an electrode suitable for the
measurement of chloride (e.g. a silver electrode or ion selective electrode for chloride) and a reference
electrode (e.g. a mercury(I) sulphate electrode). Alternatively, use a suitable combination electrode.
6.7 HPE bottles or containers, sufficiently large (500 ml to 2 000 ml) with screw cap to accommodate
the volume of the sample, extractant and at least 10 % air volume.
6.8 Analytical balance with an accuracy of 0,001 g.
6.9 Technical balance with an accuracy of 0,01 g.
6.10 Qualitative filter paper, cellulose-based ashless type.
NOTE Centrifugation is an acceptable alternative: a centrifuge with a speed of at least 3 000 rpm.
6.11 Orbital shaker, capable of holding the plastic bottles or containers (6.7) and maintaining the
sample in suspension without damaging the structure of the sample.
prEN 18252:2025 (E)
6.12 Pipettes, class AS with an accuracy of 0,1 ml.
6.13 Graduated glass cylinder, class A, with capacity 50 ml, 100 ml and 250 ml.
6.14 pH testing device, e.g. pH meter, pH indicator paper, or pH rapid test.
7 Sampling
Sampling is not part of the method specified in this document. EN 12579:2024 shall be followed dealing
with soil improvers and growing media. It is important that the laboratory receives a sample that is
representative of the product under consideration. The sample should not have been damaged or
changed during transport or storage.
8 Procedure
8.1 General
Tests conducted according to this document shall be carried out by suitably trained staff. Persons using
this document should be familiar with usual laboratory practice. This document does not purport to
address all of the safety issues, if any, associated with its use. It is the responsibility of the user to establish
appropriate health and safety practices and to ensure compliance with any national regulatory
conditions.
8.2 Temperature for measurements
To reduce the effects of thermal and electric hysteresis, the temperatures of the electrodes, the water
used for washing, the standard solutions and the test solution shall be as close to each other as possible.
The temperatures of the standard solutions and the test solution shall not differ by more than 1 °C. The
measurement temperature should be 23 °C ± 3 °C whenever possible.
8.3 Extraction of
...