kSIST FprEN 15925:2026
(Main)Inorganic fertilizers - Extraction of total sulfur present in various forms
- Abstract
This document specifies a method for the extraction of the total sulfur contained in inorganic fertilizers in elemental form and/or in other chemical combinations.
The method is applicable to inorganic fertilizers for which a declaration of the total sulfur present in various forms (elemental, thiosulfate, sulfite, sulfate) is provided.
- Status
- Not Published
- Public Enquiry End Date
- 01-Mar-2026
- Technical Committee
- KAT - Soil quality
- Current Stage
- 5020 - Formal vote (FV) (Adopted Project)
- Start Date
- 09-Oct-2026
- Due Date
- 27-Nov-2026
kSIST FprEN 15925:2026 is the SIST reference for a draft European standard on inorganic fertilizers. It specifies a laboratory method for extracting total sulfur present in elemental form and in other chemical combinations, so that sulfur can then be determined in fertilizers declared to contain elemental sulfur, thiosulfate, sulfite, or sulfate.
What does kSIST FprEN 15925:2026 specify?
kSIST FprEN 15925:2026 specifies a method for extracting total sulfur from inorganic fertilizers. The method is intended for products where the total sulfur content is declared in different forms, and the extract is prepared so sulfate can be determined afterward.
The document is organized into clauses 1 to 9, followed by a bibliography. Clause 4 covers sampling and sample preparation, clauses 5 to 8 cover the principle, reagents, apparatus, and procedure, and clause 9 sets out the test report content.
What are the key requirements of kSIST FprEN 15925:2026?
The core requirement of kSIST FprEN 15925:2026 is to convert sulfur in several chemical forms into sulfate under controlled laboratory conditions, then pass the solution on to EN 15749 for sulfate determination. In practice, the method is an extraction step, so the analyst must follow the procedure closely to avoid losses or incomplete oxidation.
Clause 4 - sampling and sample preparation
Sampling is not part of the method itself. kSIST FprEN 15925:2026 points to EN 1482-1 as the recommended sampling method and requires sample preparation in accordance with EN 1482-2.
This matters because the laboratory sample must represent the product and the analysis. The sample should not be altered during transport or storage, and grinding is recommended to improve homogeneity.
Clause 5 - principle
kSIST FprEN 15925:2026 converts elemental sulfur in alkaline medium to polysulfides and thiosulfate, then oxidizes these together with any sulfites using hydrogen peroxide. The sulfur forms are turned into sulfate, which is then determined as described in EN 15749.
In practice, the method relies on complete oxidation. If the oxidation is incomplete, the sulfate result used for the sulfur assessment will be unreliable.
Clauses 6 and 7 - reagents and apparatus
kSIST FprEN 15925:2026 requires analytical-grade reagents and distilled or demineralized water with low conductivity. It also specifies the basic equipment needed, including an adjustable electric hot plate, beakers, and a volumetric flask.
This is practical laboratory control: reagent quality and suitable glassware help limit contamination and make the oxidation and transfer steps reproducible.
Clause 8 - procedure
kSIST FprEN 15925:2026 gives a defined test portion size based on sulfur content, with the mass chosen so the amount of sulfur stays within the stated range. The procedure then uses sodium hydroxide, boiling, repeated addition of hydrogen peroxide, and further heating to complete oxidation.
After oxidation, the solution is prepared in one of two ways depending on sulfur content. Below 5 % sulfur, the whole filtrate is used after checking that the last drops are free of sulfate; above 5 %, the solution is made up to volume and an aliquot is used. This split matters because it changes how the analyst prepares the solution before sulfate determination in EN 15749.
Clause 9 - test report
kSIST FprEN 15925:2026 requires the report to identify the method used, identify the sample fully, record the sampling date and procedure if known, record when extraction finished, and note any optional steps or incidents that could affect the result.
What terms does kSIST FprEN 15925:2026 define?
- Inorganic fertilizers - The products to which the method applies, provided they declare sulfur in one or more specified forms.
- Elemental sulfur - Sulfur present in elemental form, which the method converts during oxidation.
- Thiosulfate - One of the sulfur forms covered by the scope and converted to sulfate during the method.
- Sulfite - A sulfur form that is oxidized along with the other sulfur species in the sample.
- Sulfate - The final sulfur form measured after oxidation and the link to EN 15749.
- Test portion - The weighed laboratory portion taken from the sample for the extraction procedure.
Who uses kSIST FprEN 15925:2026?
kSIST FprEN 15925:2026 is used by analytical laboratories, fertilizer manufacturers, and quality control teams that need to extract total sulfur before sulfate determination. It is relevant where fertilizer labels or declarations specify sulfur in different chemical forms and the laboratory has to confirm or support that declaration.
What changed in kSIST FprEN 15925:2026 from the previous edition?
kSIST FprEN 15925:2026 will supersede EN 15925:2011. The foreword states these significant technical changes:
- the reference to EC fertilizer was removed;
- quality parameters for distilled water were added;
- clarification was added for covering with a watch glass.
Which standards are used with kSIST FprEN 15925:2026?
- EN 1482-1 - cited in the bibliography as the general sampling provisions.
- EN 1482-2 - the required reference for general sample preparation provisions.
- EN 12944-1 - provides general fertilizer and liming materials vocabulary.
- EN 12944-2 - provides fertilizer-specific vocabulary.
- EN 15749 - gives the sulfate determination step used after the extraction.
What does the kSIST FprEN 15925:2026 document contain?
kSIST FprEN 15925:2026 contains the full laboratory workflow for sulfur extraction: the scope, the reference standards, the vocabulary basis, sample handling, the chemical principle, reagents, apparatus, step-by-step oxidation, and the preparation of the final solution for sulfate measurement. It also includes the reporting items needed to document how the test was carried out. The bibliography points to EN 1482-1 for sampling provisions.
Relations
- Effective Date
- 01-Feb-2026
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Frequently Asked Questions
kSIST FprEN 15925:2026 is a draft published by the Slovenian Institute for Standardization (SIST). Its full title is "Inorganic fertilizers - Extraction of total sulfur present in various forms". This standard covers: This document specifies a method for the extraction of the total sulfur contained in inorganic fertilizers in elemental form and/or in other chemical combinations. The method is applicable to inorganic fertilizers for which a declaration of the total sulfur present in various forms (elemental, thiosulfate, sulfite, sulfate) is provided.
This document specifies a method for the extraction of the total sulfur contained in inorganic fertilizers in elemental form and/or in other chemical combinations. The method is applicable to inorganic fertilizers for which a declaration of the total sulfur present in various forms (elemental, thiosulfate, sulfite, sulfate) is provided.
kSIST FprEN 15925:2026 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.
kSIST FprEN 15925:2026 has the following relationships with other standards: It is inter standard links to SIST EN 15925:2011. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
kSIST FprEN 15925:2026 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.
kSIST FprEN 15925:2026 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
oSIST prEN 15925:2026
01-februar-2026
Anorganska gnojila - Ekstrakcija celotnega žvepla v različnih oblikah
Inorganic fertilizers - Extraction of total sulfur present in various forms
Anorganische Düngemittel - Extraktion von Gesamtschwefel, der in verschiedener Form
vorliegen kann
Engrais inorganiques - Extraction du soufre total présent sous différentes formes
Ta slovenski standard je istoveten z: prEN 15925
ICS:
65.080 Gnojila Fertilizers
oSIST prEN 15925:2026 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN 15925:2026
oSIST prEN 15925:2026
DRAFT
EUROPEAN STANDARD
prEN 15925
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2025
ICS 65.080 Will supersede EN 15925:2011
English Version
Inorganic fertilizers - Extraction of total sulfur present in
various forms
Engrais inorganiques - Extraction du soufre total Anorganische Düngemittel - Extraktion von
présent sous différentes formes Gesamtschwefel, der in verschiedener Form vorliegen
kann
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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 15925:2025 E
worldwide for CEN national Members.
oSIST prEN 15925:2026
prEN 15925:2025 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Sampling and sample preparation . 4
5 Principle . 4
6 Reagents . 4
7 Apparatus . 5
8 Procedure . 5
8.1 Test portion . 5
8.2 Oxidation . 5
8.3 Preparation of the solution to be analysed . 5
9 Test report . 6
Bibliography . 7
oSIST prEN 15925:2026
prEN 15925:2025 (E)
European foreword
This document (prEN 15925:2025) 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 will supersede EN 15925:2011.
This document includes the following significant technical changes with respect to EN 15925:2011:
a) reference to EC fertilizer removed;
b) quality parameters for distilled water added;
c) clarification for covering with watch gl
...