FprEN 17758
(Main)Fertilizers and liming materials - Determination of the chloride content by potentiometric titration
- Abstract
This document specifies a method for the determination of the chloride content in organic fertilizers, organo-mineral fertilizers, inorganic fertilizers and liming materials by potentiometric titration.
This document is applicable to fertilizing product blends, where a blend is a mix of at least two of the following components, fertilizers and liming materials, and where the following category, organic fertilizers, organo-mineral fertilizers, inorganic fertilizers or liming materials, is the highest % in the blend by mass or volume, or in the case of liquid form, by dry mass.
If organic fertilizers, organo-mineral fertilizers, inorganic fertilizers, or liming materials is not the highest % in the blend, the European Standard for the highest % of the blend applies. In case a fertilizing product blend is composed of components in equal quantity, the user decides which standard to apply.
NOTE Variations in analytical methods for fertilizing product blends can lead to differing results as some components or matrix interactions can affect the outcome. Validation procedures have shown that developed standard methods are robust and reliable across diverse product compositions, but possible interferences and unexpected results when analysing fertilizing product blends are possible.
- Status
- Not Published
- Publication Date
- 03-Feb-2027
- Technical Committee
- CEN/TC 260 - Fertilizers and liming materials
- Drafting Committee
- CEN/TC 260/WG 7 - Chemical analysis
- Current Stage
- 4599 - Dispatch of FV draft to CMC - Finalization for Vote
- Start Date
- 20-Aug-2026
- Due Date
- 31-Aug-2027
- Completion Date
- 20-Aug-2026
FprEN 17758 is a CEN draft European Standard for determining chloride content in organic fertilizers, organo-mineral fertilizers, inorganic fertilizers, and liming materials by potentiometric titration. It is written for laboratories and other users who need a standardized way to measure chloride in these fertilizing materials and report results in a comparable form.
What does FprEN 17758 specify?
FprEN 17758 specifies a potentiometric titration method for chloride in the listed fertilizer and liming material categories, including certain fertilizing product blends. Clause 1 ties the method to the material category that is present at the highest percentage by mass, volume, or dry mass for liquid products, so the choice of standard depends on the blend composition.
The document is organized into clauses for the scope, normative references, terms and definitions, principle, reagents, apparatus and equipment, sampling and sample preparation, procedure, calculation and expression of results, precision, and test report. Annex A is informative and gives inter-laboratory study results; the Bibliography lists related sampling, extraction, chlorides, and precision standards.
What are the key requirements of FprEN 17758?
Measurement principle and setup
Clause 4 says FprEN 17758 measures chloride after dissolving it in water and precipitating it in an acidified medium with silver nitrate. The end point is found by tracking the voltage between electrodes, so the lab needs a working potentiometric titration system and a clear equivalence point on the titration curve.
Reagents and equipment
Clauses 5 and 6 require analytical-grade reagents, chloride-free water, nitric acid, silver nitrate standard solution, PVA solution, sodium chloride standards, and a sodium chloride control test sample. In practice, this means the laboratory must control contamination carefully, because stray chloride or poor reagent quality can shift the result.
The equipment list includes the titration system, silver or chloride-selective electrode, reference electrode, balance, filter paper, and a pH testing device. This matters because the method depends on accurate weighing, clean filtration, and pH control near the end point.
Sampling, sample preparation, and test portion
Clause 7 points to EN 1482-2 for sample preparation, and recommends grinding for homogeneity. Clause 7.1 says sampling itself is outside the method, but the laboratory should receive a representative sample that has not changed during transport or storage.
Clause 8.1 gives the preparation of the test portion and sample solution. The sample is boiled with water, cooled, diluted, and filtered, with alternatives allowed for easily water-soluble chlorides and, for organic and organo-mineral fertilizers, centrifugation instead of filtration. In practice, this step is about getting chloride into solution while removing solids that could affect the electrode or endpoint.
Calibration and determination
Clause 8.2 requires calibration of the system by titrating sodium chloride standard solution and calculating the titre factor from repeated titrations. Clause 8.3 then sets the determination step: the aliquot taken for analysis must contain no more than 0.150 g of chloride, the pH must be adjusted to below 2, and the silver nitrate consumption should fall in a workable titration range.
This is important because the method is sensitive to acidity and to the size of the titration volume. If the sample is not filtered, Clause 8.3 recommends motorized stirring to avoid clogging the electrodes.
Control test, calculation, and precision
Clause 8.4 requires a control test with freshly prepared sodium chloride solution before the analysis series. Clause 9 expresses the result as chloride in the sample as received, using the formula based on titre factor, volumes, and sample mass.
Clause 10 gives the precision framework and uses repeatability and reproducibility limits from the inter-laboratory study. For users, this is what supports comparison of results between the same lab and different laboratories.
Test report
Clause 11 requires the report to identify the sample, state the method used, give the results, and record sampling details, completion date, and any optional steps or incidents that may have influenced the outcome. This is the record that lets another party understand how the result was produced.
What terms does FprEN 17758 define?
- Potentiometric titration - a titration method that follows the electrode voltage to locate the end point.
- Titre factor - the factor used to correct or standardize the silver nitrate solution against sodium chloride.
- Test portion - the weighed portion of sample taken for preparation and analysis.
- Sample solution - the liquid prepared from the sample and used for the chloride determination.
- Control test sample - a freshly prepared sodium chloride solution used to check method accuracy before measurements.
- Repeatability - closeness of results from the same method, same lab, same operator, same equipment, and a short time interval.
- Reproducibility - closeness of results obtained in different laboratories with different operators and equipment.
Who uses FprEN 17758?
FprEN 17758 is used by analytical laboratories, quality control teams, fertilizer manufacturers, and organizations buying or verifying fertilizing products and liming materials. It is relevant wherever chloride content must be measured in a reproducible way for product control, batch comparison, or technical specification checks.
What changed in FprEN 17758 from the previous edition?
FprEN 17758 is prepared to supersede CEN/TS 17758:2022. The stated technical changes are the adoption of the technical specification as a European Standard, an updated scope for fertilizing product blends, inclusion of water as a reagent, an added centrifuge option for preparation of organic and organo-mineral fertilizer test portions, inclusion of precision data, addition of Annex A with inter-laboratory study results, and revision of the normative references and bibliography.
Which standards are used with FprEN 17758?
- EN 1482-2 - provides the general sample preparation provisions used in Clause 7.
- EN 12944-1, EN 12944-2, EN 12944-3 - provide the vocabulary and terms applied in Clause 3.
- EN 1482-1 and EN 1482-3 - are named for recommended sampling methods in Clause 7.1 and in the Bibliography.
- EN 15958 - is cited as an alternative sample preparation approach in Clause 8.1.
- EN 16195 - is listed in the Bibliography as a related chloride method for materials without organic matter.
- ISO 5725-2 and ISO 5725-3 - are used for the repeatability and reproducibility treatment in Clause 10.
What does the FprEN 17758 document contain?
FprEN 17758 contains the analytical principle, reagent requirements, apparatus list, sampling and sample preparation instructions, titration procedure, calculation formula, precision data, and test report content. It also includes a control test step and a worked precision framework based on inter-laboratory study results.
Annex A summarizes the inter-laboratory study used to establish precision, and Table 1 gives mean values together with repeatability and reproducibility limits for representative sample types. The document therefore supports routine testing, method verification, and reporting of chloride results for fertilizers and liming materials.
Relations
- Effective Date
- 01-May-2024
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Frequently Asked Questions
FprEN 17758 is a draft published by the European Committee for Standardization (CEN). Its full title is "Fertilizers and liming materials - Determination of the chloride content by potentiometric titration". This standard covers: This document specifies a method for the determination of the chloride content in organic fertilizers, organo-mineral fertilizers, inorganic fertilizers and liming materials by potentiometric titration. This document is applicable to fertilizing product blends, where a blend is a mix of at least two of the following components, fertilizers and liming materials, and where the following category, organic fertilizers, organo-mineral fertilizers, inorganic fertilizers or liming materials, is the highest % in the blend by mass or volume, or in the case of liquid form, by dry mass. If organic fertilizers, organo-mineral fertilizers, inorganic fertilizers, or liming materials is not the highest % in the blend, the European Standard for the highest % of the blend applies. In case a fertilizing product blend is composed of components in equal quantity, the user decides which standard to apply. NOTE Variations in analytical methods for fertilizing product blends can lead to differing results as some components or matrix interactions can affect the outcome. Validation procedures have shown that developed standard methods are robust and reliable across diverse product compositions, but possible interferences and unexpected results when analysing fertilizing product blends are possible.
This document specifies a method for the determination of the chloride content in organic fertilizers, organo-mineral fertilizers, inorganic fertilizers and liming materials by potentiometric titration. This document is applicable to fertilizing product blends, where a blend is a mix of at least two of the following components, fertilizers and liming materials, and where the following category, organic fertilizers, organo-mineral fertilizers, inorganic fertilizers or liming materials, is the highest % in the blend by mass or volume, or in the case of liquid form, by dry mass. If organic fertilizers, organo-mineral fertilizers, inorganic fertilizers, or liming materials is not the highest % in the blend, the European Standard for the highest % of the blend applies. In case a fertilizing product blend is composed of components in equal quantity, the user decides which standard to apply. NOTE Variations in analytical methods for fertilizing product blends can lead to differing results as some components or matrix interactions can affect the outcome. Validation procedures have shown that developed standard methods are robust and reliable across diverse product compositions, but possible interferences and unexpected results when analysing fertilizing product blends are possible.
FprEN 17758 is classified under the following ICS (International Classification for Standards) categories: 65.080 - Fertilizers. The ICS classification helps identify the subject area and facilitates finding related standards.
FprEN 17758 has the following relationships with other standards: It is inter standard links to CEN/TS 17758:2022. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
FprEN 17758 is associated with the following European legislation: EU Directives/Regulations: 2019/1009; Standardization Mandates: M/564, M/564 AMD 1, M/564 AMD 2. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
FprEN 17758 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-april-2026
Gnojila in sredstva za apnjenje - Določanje klorida s potenciometrijsko titracijo
Fertilizers and liming materials - Determination of the chloride content by potentiometric
titration
Düngemittel und Kalkdünger - Bestimmung des Chloridgehaltes mittels
potentiometrischer Titration
Engrais et amendements minéraux basiques - Détermination de la teneur en chlorures
par titrage potentiométrique
Ta slovenski standard je istoveten z: prEN 17758
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
prEN 17758
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2026
ICS 65.080 Will supersede CEN/TS 17758:2022
English Version
Fertilizers and liming materials - Determination of the
chloride content by potentiometric titration
Engrais et amendements minéraux basiques - Düngemittel und Kalkdünger - Bestimmung des
Détermination de la teneur en chlorures par titrage Chloridgehaltes mittels potentiometrischer Titration
potentiométrique
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 260.
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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17758:2026 E
worldwide for CEN national Members.
prEN 17758:2026 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Reagents . 5
6 Apparatus and equipment . 5
7 Sampling and sample preparation . 6
7.1 Sampling . 6
7.2 Sample preparation . 6
8 Procedure . 6
8.1 Preparation of the test portion and the sample solution . 6
8.2 Calibration of the system (titre factor) . 6
8.3 Determination . 7
8.4 Control test . 7
9 Calculation and expression of the results . 7
10 Precision . 7
10.1 Inter-laboratory study . 7
10.2 Repeatability . 8
10.3 Reproducibility . 8
11 Test report . 9
Annex A (informative) Results of the inter-laboratory study . 10
Bibliography . 12
prEN 17758:2026 (E)
European foreword
This document (prEN 17758:2026) has been prepared by Technical Committee CEN/TC 260 “Fertilizers
and liming materials”, the secretariat of which is held by DIN.
This document is currently submitted to 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 17758:2026 includes the following significant technical changes with respect to
CEN/TS 17758:2022:
— The CEN Technical Specification has been adopted as a European Standard;
— Scope (Clause 1) updated regarding the applicability to fertilizing product blends;
— Water as reagent has been included (5.1);
— The option to use a centrifuge for the preparation of test portion (8.1) of organic and organic-mineral
fertilizers added;
— The precision data (Clause 10) of the validation study included;
— Annex A including results of inter-laboratory study added;
— Normative references (Clause 2) and Bibliography revised.
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 17758:2026 (E)
1 Scope
This document specifies a method for the determination of the chloride content in organic fertilizers,
organo-mineral fertilizers, inorganic fertilizers and liming materials by potentiometric titration.
This document is applicable to fertilizing product blends, where a blend is a mix of at least two of the
following components, fertilizers and liming materials, and where the following category, organic
fertilizers, organo-mineral fertilizers, inorganic fertilizers or liming materials, is the highest % in the
blend by mass or volume, or in the case of liquid form, by dry mass.
If organic fertilizers, organo-mineral fertilizers, inorganic fertilizers, or liming materials is not the highest
% in the blend, the European Standard for the highest % of the blend applies. In case a fertilizing product
blend is composed of components in equal quantity, the user decides which standard to apply.
NOTE Variations in analytical methods for fertilizing product blends can lead to differing results as some
components or matrix interactions can affect the outcome. Validation procedures have shown that developed
standard methods are robust and reliable across diverse product compositions, but possible interferences and
unexpected results when analysing fertilizing product blends are possible.
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.
EN 1482-2, Fertilizers, liming materials and inhibitors — Sampling and sample preparation — Part 2:
General sample preparation provisions
EN 12944-1, Fertilizers, liming materials and inhibitors — Vocabulary — Part 1: General terms
EN 12944-2, Fertilizers, liming materials and inhibitors — Vocabulary — Part 2: Terms relating to
fertilizers
EN 12944-3, Fertilizers, liming materials and inhibitors — Vocabulary — Part 3: Terms relating to liming
materials
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-1, EN 12944-2 and
EN 12944-3 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/
4 Principle
The chlorides, dissolved in water, are precipitated in an acidified medium by a standard solution of silver
nitrate. The chloride concentration in the samples is quantified by potentiometric determination. To
detect the end point, the voltage between a reference electrode on the one hand and the silver electrode
or an ion selective electrode on the other hand, is tracked. This voltage depends on the logarithm of the
chloride ion activity. If it is plotted, in mV, on the ordinate and the silver nitrate solution, in ml, on the
Under revision. Stage at the time of preparation: prEN 12944-1:2026
Under revision. Stage at the time of preparation: prEN 12944-2:2026
prEN 17758:2026 (E)
abscissa, the point of inflection of the curve obtained in this manner is the equivalence point. Equivalent
methods of evaluation are permitted [4, 6].
5 Reagents
Use only reagents of recognized analytical grade.
5.1 Water, distilled or demineralized with a specific conductivity not higher than 0,2 mS/m at 25 °C,
free from chloride.
5.2 Nitric acid, substance concentration c = 16 mol/l.
5.3 Nitric acid solu
...