FprEN 15475
(Main)Inorganic fertilizers - Titrimetric determination of ammoniacal nitrogen
- Abstract
This document specifies a method for the titrimetric determination of the ammoniacal nitrogen content in inorganic fertilizers (including compound fertilizers), in which nitrogen is found exclusively either in the form of ammonium salts or ammonium salts together with nitrates.
This document is applicable to fertilizing product blends, where the blend is a mix of at least two of the following components: fertilizers, liming materials, soil improvers, growing media, inhibitors, plant biostimulants and where the following category: inorganic fertilizers is the highest % in the blend by mass or volume, or in the case of liquid form by dry mass. If inorganic fertilizers are 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 is not applicable to fertilizers or fertilizer product blends containing urea, cyanamide, nutrient polymers or other organic nitrogenous compounds.
- Status
- Not Published
- Publication Date
- 13-Jan-2027
- Technical Committee
- CEN/TC 260 - Fertilizers and liming materials
- Drafting Committee
- CEN/TC 260/WG 7 - Chemical analysis
- Current Stage
- 5020 - Submission to Vote - Formal Approval
- Start Date
- 24-Sep-2026
- Due Date
- 03-Jul-2027
- Completion Date
- 24-Sep-2026
FprEN 15475 is a CEN draft European Standard for the titrimetric determination of ammoniacal nitrogen in inorganic fertilizers. It specifies a distillation and back-titration method for inorganic fertilizers and certain fertilizing product blends, and it is intended for laboratories and technical staff who test fertilizer composition.
What does FprEN 15475 specify?
FprEN 15475 specifies a method for measuring ammoniacal nitrogen in inorganic fertilizers, including compound fertilizers, where the nitrogen is present only as ammonium salts or as ammonium salts together with nitrates. It also applies to certain fertilizing product blends when inorganic fertilizers are the largest component by mass, volume, or dry mass for liquid products.
The document is organized into clauses on scope, normative references, terms and definitions, principle, reagents, apparatus, sampling and sample preparation, procedure, calculation and expression of the result, precision, and test report, followed by Annex A.
| Annex | What it covers |
|---|---|
| Annex A | Results of the inter-laboratory tests, used as the basis for the precision data |
FprEN 15475 does not apply to fertilizers or fertilizing product blends containing urea, cyanamide, nutrient polymers, or other organic nitrogenous compounds. For blends with equal quantities of components, the user decides which standard to apply.
What are the key requirements of FprEN 15475?
Measurement principle
FprEN 15475 measures ammoniacal nitrogen by adding excess sodium hydroxide solution, converting ammoniacal nitrogen to ammonia, distilling the ammonia into a known amount of sulfuric acid, and then back titrating the excess acid with sodium hydroxide or potassium hydroxide. In practice, the method depends on complete transfer of ammonia and a clear titration end point.
Sampling, reagents and apparatus
FprEN 15475 requires sample preparation in accordance with EN 1482-2, while sampling itself is outside the method. The laboratory sample must be representative and unchanged during transport or storage, because poor sampling will affect the result before analysis starts.
The method uses analytical-grade reagents, low-conductivity water, and a balance readable to 0,001 g. It describes indicator solutions, carbonate-free alkali, ammonia-free concentrated sodium hydroxide, and distillation apparatus, including automated options if the operator proves statistically equivalent results against the precision criteria.
Procedure, variants and checks
FprEN 15475 gives three procedure variants, labeled a, b and c, with different sample masses, dilution levels, receiving acid strengths and back-titration strengths. The variants are matched to increasing nitrogen ranges, so the analyst selects the setup that fits the expected ammoniacal nitrogen content.
The method also allows direct weighing without sample dissolution for samples known to be free of bound carbon dioxide, if equivalence to the precision criteria is demonstrated. That matters when a simpler preparation route is acceptable, but only after validation.
Before routine analysis, FprEN 15475 requires a blank test and a control test with freshly prepared ammonium sulfate solution, or an equivalent solid amount for the chosen variant. These checks confirm that the apparatus and the procedure are working correctly.
Result, precision and reporting
FprEN 15475 expresses the result as percentage mass fraction of ammoniacal nitrogen in the fertilizer as received for analysis. Precision is supported by inter-laboratory test data and by repeatability and reproducibility limits, which are given for several fertilizer types.
The test report has to identify the sample, state the method used with the document reference, give the result, and record sampling details if known, the completion date, and any optional steps or incidents that could have influenced the result.
What terms does FprEN 15475 define?
- Ammoniacal nitrogen - nitrogen measured in this document when it is present as ammonium salts, with or without nitrates.
- Fertilizing product blend - a mix of at least two components such as fertilizers, liming materials, soil improvers, growing media, inhibitors, and plant biostimulants.
- Blank test - a parallel determination run under the same conditions as the sample, used to correct the final result.
- Control test - a check performed before analysis to confirm that the method and apparatus are functioning properly.
- Repeatability - the closeness of results obtained in the same laboratory under the same conditions.
- Reproducibility - the closeness of results obtained in different laboratories under different conditions.
- Direct weighing without sample dissolution - an allowed approach for suitable samples when equivalence to the required precision has been demonstrated.
Who uses FprEN 15475?
FprEN 15475 is used by laboratories that analyze fertilizers and fertilizing product blends for ammoniacal nitrogen content. It is also relevant to quality control and technical teams in the fertilizers sector who need a defined method for routine testing, validation, or product release.
What changed in FprEN 15475 from the previous edition?
FprEN 15475:2026 will supersede EN 15475:2009. The stated changes are that the measurement principle was added to the title, the normative references were revised, references to Regulation (EC) No 2003/2003 were removed, water specifications were revised, reagents and apparatus were revised, and explanatory notes were added.
Which standards are used with FprEN 15475?
- EN 1482-2 - gives the general provisions for sample preparation used before the analysis.
- EN 1482-1 - gives recommended general sampling provisions.
- EN 1482-3 - gives sampling of static heaps.
- EN 12944-1 - provides general fertilizer and liming material vocabulary used in the document.
- EN 12944-2 - provides fertilizer-related terms and definitions used in the document.
- ISO 5725-1 - provides the general principles used for the repeatability and reproducibility evaluation.
What does the FprEN 15475 document contain?
FprEN 15475 contains the reagents list, apparatus requirements, and several distillation set-ups shown in Figures 1 to 4. It also gives three calculation variants in Tables 1 to 3, including the sample mass, dilution, receiving solution, and back-titration conditions for each variant.
Clause 8 covers sample solution preparation, distillation, titration, the blank test, and the control test. Clause 9 gives the calculation approach, Clause 10 gives precision data based on an inter-laboratory test, and Clause 11 lists the required contents of the test report. Annex A provides the statistical results of the inter-laboratory study used for the precision statement.
Relations
- Effective Date
- 23-Jul-2025
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Frequently Asked Questions
FprEN 15475 is a draft published by the European Committee for Standardization (CEN). Its full title is "Inorganic fertilizers - Titrimetric determination of ammoniacal nitrogen". This standard covers: This document specifies a method for the titrimetric determination of the ammoniacal nitrogen content in inorganic fertilizers (including compound fertilizers), in which nitrogen is found exclusively either in the form of ammonium salts or ammonium salts together with nitrates. This document is applicable to fertilizing product blends, where the blend is a mix of at least two of the following components: fertilizers, liming materials, soil improvers, growing media, inhibitors, plant biostimulants and where the following category: inorganic fertilizers is the highest % in the blend by mass or volume, or in the case of liquid form by dry mass. If inorganic fertilizers are 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 is not applicable to fertilizers or fertilizer product blends containing urea, cyanamide, nutrient polymers or other organic nitrogenous compounds.
This document specifies a method for the titrimetric determination of the ammoniacal nitrogen content in inorganic fertilizers (including compound fertilizers), in which nitrogen is found exclusively either in the form of ammonium salts or ammonium salts together with nitrates. This document is applicable to fertilizing product blends, where the blend is a mix of at least two of the following components: fertilizers, liming materials, soil improvers, growing media, inhibitors, plant biostimulants and where the following category: inorganic fertilizers is the highest % in the blend by mass or volume, or in the case of liquid form by dry mass. If inorganic fertilizers are 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 is not applicable to fertilizers or fertilizer product blends containing urea, cyanamide, nutrient polymers or other organic nitrogenous compounds.
FprEN 15475 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 15475 has the following relationships with other standards: It is inter standard links to EN 15475:2009. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
FprEN 15475 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 15475 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 15475:2026
01-marec-2026
Anorganska gnojila - Titrimetrijsko določanje amonijevega dušika
Inorganic fertilizers - Titrimetric determination of ammoniacal nitrogen
Anorganische Düngemittel - Titrimetrische Bestimmung von Ammoniumstickstoff
Engrais inorganiques - Dosage titrimétrique de l’azote ammoniacal
Ta slovenski standard je istoveten z: prEN 15475
ICS:
65.080 Gnojila Fertilizers
oSIST prEN 15475:2026 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN 15475:2026
oSIST prEN 15475:2026
DRAFT
EUROPEAN STANDARD
prEN 15475
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2026
ICS 65.080 Will supersede EN 15475:2009
English Version
Inorganic fertilizers - Titrimetric determination of
ammoniacal nitrogen
Engrais inorganiques - Dosage titrimétrique de l'azote Anorganische Düngemittel - Titrimetrische
ammoniacal Bestimmung von Ammoniumstickstoff
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 15475:2026 E
worldwide for CEN national Members.
oSIST prEN 15475:2026
prEN 15475:2026 (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 . 6
7 Sampling and sample preparation . 11
7.1 Sampling . 11
7.2 Sample preparation . 11
8 Procedure . 11
8.1 Preparation of the sample solution . 11
8.1.1 General. 11
8.1.2 Direct weighing without sample dissolution . 11
8.2 Distillation of the sample solution. 11
8.3 Titration of the sample solution . 12
8.4 Blank . 14
8.5 Control test . 14
9 Calculation and expression of the result . 14
10 Precision . 14
10.1 Inter-laboratory test . 14
10.2 Repeatability . 14
10.3 Reproducibility . 15
11 Test report . 15
Annex A (informative) Results of the inter-laboratory tests . 16
Bibliography . 17
oSIST prEN 15475:2026
prEN 15475:2026 (E)
European foreword
This document (prEN 15475:2026) 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 will supersede EN 15475:2009.
prEN 15475:2026 includes the following significant technical changes with respect to EN 15475:2009:
a) measurement principle added to title;
b) normative references revised;
c) references to Regulation (EC) No 2003/2003 removed;
d) specifications for water revised;
e) reagents and apparatus revised;
f) explanatory notes added.
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.
oSIST prEN 15475:2026
prEN 15475:2026 (E)
1 Scope
This document specifies a method for the titrimetric determination of the ammoniacal nitrogen content
in inorganic fertilizers (including compound fertilizers), in which nitrogen is found exclusively either in
the form of ammonium salts or ammonium salts together with nitrates.
This document is applicable to the fertilizing products blends where a blend is a mix of at least two of the
following components: fertilizers, liming materials, soil improvers, growing media, inhibitors, plant
biostimulants and where the following category: inorganic fertilizers is the highest % in the blend by
mass or volume, or in the case of liquid form by dry mass. If inorganic fertilizers are 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. 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.
In the case of application to ammonium nitrate fertilizers of high nitrogen content, this document is not
applicable to fertilizer product blends.
This document is not applicable to fertilizers or fertilizer product blends containing urea, cyanamide,
nutrient polymers or other organic nitrogenous compounds.
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 and liming materials — Vocabulary — Part 1: General terms
EN 12944-2, Fertilizers and liming materials — Vocabulary — Part 2: Terms relating to fertilizers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12944-1 and EN 12944-2 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/
4 Principle
An excess of sodium hydroxide solution is added to the sample. This converts the ammoniacal nitrogen
contained into ammonia, which is transferred into a known volume of sulphuric acid standard solution
by distillation. The excess acid is determined by titration with sodium hydroxide or potassium hydroxide
standard solution.
oSIST prEN 15475:2026
prEN 15475:2026 (E)
5 Reagents
Use only reagents of recognized analytical grade.
5.1 Water. The electrical conductivity of distilled or demineralized water used in the analysis shall at
least be < 0,5 mS/m (at 25 °C).
5.2 Hydrochloric acid, c = 12 mol/l, w = 37 %, ρ20 °C = 1,18 g/ml.
°C = 1,10 g/ml.
5.3 Hydrochloric acid solution, c = 6 mol/l, w = 20 %, ρ20
In a fume cupboard, transfer 500 mL of hydrochloric acid (5.2) into a 1000 mL volumetric flask and dilute
to the mark with water.
5.4 Sulfuric acid standard solution, c = 0,05 mol/l.
For variant a, see 8.3.
5.5 Sodium or potassium hydroxide standard solution, c = 0,1 mol/l, carbonate free.
For variant a, see 8.3.
5.6 Sulfuric acid standard solution, c = 0,1 mol/l.
For variant b, see 8.3.
5.7 Sodium or potassium hydroxide standard solution, c = 0,2 mol/l, carbonate free.
For variant b, see 8.3.
5.8 Sulfuric acid standard solution, c = 0,25 mol/l.
For variant c, see 8.3.
5.9 Sodium or potassium hydroxide standard solution, c = 0,5 mol/l, carbonate free.
For variant c, see 8.3.
5.10 Concentrated sodium hydroxide solution, c = 10 mol/l, w = 30 %, ρ °C = 1,33 g/ml, ammonia
free.
5.11 Methyl red.
5.12 Methylene blue.
5.13 Ethanol, φ = 95 %.
5.14 Indicator solutions.
5.14.1 Mixed indicator.
Solution A: Dissolve 1 g of methyl red (5.11) in 37 ml of sodium hydroxide solution (5.5) and make up
to 1 l with water.
Solution B: Dissolve 1 g of methylene blue (5.12) in water and make up to 1 l.
Mix one volume of A with two volumes of B.
oSIST prEN 15475:2026
prEN 15475:2026 (E)
This indicator is violet in acid solution, grey in neutral solution and green in alkaline solution. Use 0,5 ml
(10 drops) of this indicator solution.
5.14.2 Methyl red indicator solution.
Dissolve 0,1 g of methyl red (5.11) in 50 ml of ethanol (5.13). Make up to 100 ml with water and filter if
necessary. This indicator may be used (4 to 5 drops) instead of the preceding one. This indicator is red in
acid solution and yellow in alkaline solution.
5.15 Ammonium sulfate.
6 Apparatus
6.1 Balance, with a readability of ≤ 0,001 g.
6.2 Graduated flasks, capacity 500 ml.
6.3 Pipettes, capacity of 10 ml, 20 ml, 25 ml, 50 ml, 100 ml and 200 ml.
6.4 Rotary shaker, 35 to 40 r/min.
6.5 Filter, free of nitrogen, e.g. 100 % cellulose
6.6 Distillation apparatus.
Consisting of a round-bottomed flask of suitable capacity connected to a condenser by means of a splash
head. The equipment is made of borosilicate glass.
Figures 1 to 4 show possible different types of equipment for this determination via non-automated
distillation, including all construction features.
Alternatively, automated distillation and/or titration apparatuses equipped with sensors for photometric
determination or with pH electrodes for potentiometric determination may be used. The operator shall
demonstrate, by means of statistically equivalent results, that the automated devices comply with the
precision criteria specified in Annex A. The operation shall comply with the necessary safety precautions
and the corresponding user manuals, including the precautions required to avoid ammonia loss.
6.7 Anti-bump granules, i.e. pumice stone, glass pearls, washed in hydrochloric acid and calcined.
oSIST prEN 15475:2026
prEN 15475:2026 (E)
Dimensions in millimetres
Key
1 round-bottomed, long-necked flask of 1 000 ml capacity
2 distillation tube with a splash head, connected to the condenser by means of a spherical joint (No 18) (the
spherical joint for the connection to the condenser may be replaced by an appropriate rubber connection)
3 funnel with a polytetrafluoroethylene (PTFE) tap (6) for the addition of sodium hydroxide
4 six-bulb condenser with spherical joint (No 18) at the entrance, and joined at the issue to a glass extension
tube by means of a small rubber connection (when the connection to the distillation tube is effected by means of a
rubber tube, the spherical joint may be replaced by a suitable rubber bung)
5 500-ml-flask in which the distillate is collected
6 PTFE-tap (the tap may l
...